A Momentous Week in Our Pandemic Response

This guest post was written by Jorge Salinas, MD, Hospital Epidemiologist at the University of Iowa Hospitals & Clinics. 

Her saturation had dropped to 89. Fever persisted. She was being admitted. This was the telegraphic message that started a roller coaster of a week. My mother had been symptomatic for a few days but had suddenly worsened. By 7:45 that same morning, we received confirmation—shipment was completed, 975 doses were on the dock, the vaccination deployment plan was a go.

A quick morning huddle. Everyone knew their positions and what to do: teams to prepare the doses, employee health nurses to administer them, planners to manage schedules. It was nicely choreographed and rehearsed.

The New York Times, 12/18/20

ED nurse, environmental services custodian, doctor, resident. How many people received the dose before me? Ten? Twenty? Jorge, this way. Immediately after the shot, I was asked, on camera, how I felt now that I had received the precious vaccine. This was undoubtedly a triumph of science. One of the greatest medical breakthroughs in years. And I had received it. Yet, I couldn’t avoid feeling unworthy of it. Because I am part of our system pandemic response I had more access to the vaccine than those more at risk. I had reluctantly persuaded myself that being a Hospital Epidemiologist and a Hispanic physician it would be advantageous to our response. To lead by example, show my healthcare colleagues here and abroad that I have confidence in the vaccine development process, that these vaccines are efficacious and safe. Took a big swallow, don’t think of mom right now, take a deep breath, go on.   

I am not an ethicist. I believe that the fair allocation of scarce resources is one of the hardest feats in medicine. We had debated extensively: how could we allocate these first thousand doses amongst almost 20,000 healthcare workers? Who should get it? Those over the age of 65? Those working in COVID units? Those on oncology and transplant floors? Should it be a lottery? Should we factor in healthcare worker comorbidities? Why did they send only 975 doses? We decided to prioritize every frontline, doctor, nurse, respiratory therapist, trainee, environmental services worker, etc., assigned to our inpatient and outpatient COVID units. After them, healthcare workers across all lines in all other units would be given the vaccine. Most States have less than 20% of doses needed for healthcare workers at the moment. 

Source: Vox.com

By mid-week we had vaccinated hundreds of people across all work lines in the first priority group. Questions of course came in: When is my turn? Why is my unit in phase one or two? But all in all, people were gracious and kind and most are still patiently awaiting their turn. A question arose though that was a bit harder to answer. If there is a cancellation, who should get that dose? Whoever can come in faster? Here again, came another simple realization: there are barriers to vaccination, even among healthcare workers. Those in support services and trainees even within our system would have a harder time to stop doing what they are doing at work, arrange day care, or plan for the possibility of a couple of days off after their shot in case of side effects. Quickly reacting and sprinting to get into an opening could disadvantage some groups over others. We had planned for an equal allocation to all work lines in high-risk areas but it was clear that some employees have additional barriers to vaccination.

Support service workers, trainees, housekeepers. Weren’t they also at higher risk of exposure outside of work? Our data has shown that most exposures among healthcare workers were nonoccupational. Had my job as a healthcare epidemiologist biased me to focus protection mostly while at work? But what about when in the community? I realized that when deploying vaccines, we should think of high risk of exposure at work of course, but some groups had a higher risk of COVID outside of work, in addition to potential barriers to getting the first doses of vaccines even if allocated to them.

Fair allocation of vaccine doses is not easy. Aiming for fair may not even be enough. At work and in the community, we need to work extra hard to reach those with less resources, those who chronically have barriers to access to care. These lessons from my own healthcare system will guide how I think about vaccine allocation for subsequent groups. After healthcare workers and people living in long-term care facilities are vaccinated, how are we to prioritize the next groups? It is clear that we have to actively reach those at an increased risk of acquisition however hard it may be.

While it will take several months and ethical conundrums will continue to arise locally, what about the rest of the world? Mom was a laboratory technician before she had us. If she had still been working, when would a dose have reached her in distant Peru? The global vaccine pipeline is not looking very promising for resource limited countries. The same challenges seen locally are present on a world scale. Resource limited countries may not reach full coverage until very late in 2021 or 2022. Who looks after a fair allocation of vaccines on a global level?

Source: Duke Global Health Innovation Center

 

Source: The Economist

As we close this week, I feel grateful to have received the vaccine, to work in healthcare epidemiology, to continue learning from my mistakes, and I strive to be just in our protection efforts for healthcare workers and our communities. I am grateful my mother is recovering, for my colleagues taking care of her and the hundreds of thousands of people battling COVID-19 worldwide.

The next weeks and months will continue being challenging. It is clear we have entered a new phase in the pandemic, but until we reach high vaccination coverage we must continue implementing nonpharmacologic interventions, masks, avoiding indoor crowds, and maintaining our distance. We must also advocate for just allocation of medical resources in our local and global societies. Hundreds of thousands of lives can still be saved.

COVID-19 Transmission: Medicine Grand Rounds at UCSF

Let's Just Get Every Face Covered

Photo by cottonbro at pexels.com

In the over decade-long history of this blog, Dan's recent post, A Tiresome SPAT, has been viewed more times than any other post we've ever written. And it's only been up 48 hours. This is a testament to Dan's ability to encapsulate the controversy regarding SARS-CoV-2 transmission in a billiant way. As I reflected on his writing, it became increasingly clear to me that the source of the controversy of whether we are dealing with droplet transmission or aerosol transmission is deeply rooted in the framework through which you're viewing the issue. These frames are associated with different values and ways of thinking, and depending on the frame utilized determines your recommmendations for mitigating transmission.

The first framework I'll describe is the medical (i.e., individual patient) frame. Imagine a patient visiting their physician and asking what they can do to best avoid COVID-19 infection. In addition to social distancing and hand hygiene, the physician would likely recommend a mask and eye protection. The physician might even recommend an N95 respirator depending on the patient's underlying conditions, the context of their exposures, and the patient's risk tolerance. In general, in this framework, risk tolerance is low, and the goal is typically to reduce the individual's risk to the irreducible minimum. This approach drives the occupational health perspective. PPE is viewed from the standpoint of efficacy--how do we provide ideal protection?

Now, let's look at the public health (i.e., population) framework. From this perspective, the goal is not necessarily to prevent every possible case of COVID-19, but rather to bring the outbreak to an end. This requires reducing the R0 to less than one. Thus, the interventions don't need to be perfect, and individual risk is tolerated to a somewhat greater degree. And in this framework, the PPE recommended is that which is most effective (i.e., how well does it work in the real world?), which factors in adherence. Let's say that face covering A is 90% efficacious, but only 20% of people are willing to wear it. On the other hand, face covering B is 60% efficacious, but 80% of people are willing to wear it. We're clearly better off with face covering B. The public health framework is driven by a utilitarian perspective--accomplishing the greatest good for the population, not for any given individual patient. 

Our recent JAMA viewpoint, Moving Personal Protective Equipment into the Communnity, in which we argue for universal face shields in the community settting, was written from a public health framework. This was perhaps not clear to the many individuals who pointed out that in some cases there could be airborne transmission of the virus for which a face shield may not work. Yes, we get that, but the epidemiology convinces us that the airborne route is a minor mechanism of transmission.

The bottom line here is that we can't let perfect be the enemy of the good. We recommend influenza vaccine every year despite an average seasonal effectiveness of approximately 40%. The best face covering is the face covering that people will wear. Though I personally favor face shields for community use, I am happy to see faces covered in almost any way possible (which is why I love the photo above). 

And if it's not bad enough that experts are not in agreeement, we have the additional problems of botched messaging by the CDC and political leaders who by intentionally sowing doubt and refusing to be good role models, make this work all the harder. Kudos to those leaders who are mandating face coverings. And my message to everyone is this: for community settings, let's just get everyone in a face covering now, whichever one works for them. After the pandemic is over, we can sort it out once and for all. 

A tiresome SPAT

I’m surprised that we can’t stop arguing about the modes of SARS-CoV-2 transmission, despite the fact that most experts (including our friends at WHO) agree on the important issues. Our colleague Jorge Salinas very nicely summarized these issues (and their implications) in this post.

The latest kerfuffle: media coverage of 239 experts who are upset that the WHO is not acting as decisively as they’d like on an evidence base that the experts themselves admit is far from definitive.

As we’ve outlined here and here, a major problem plaguing this discussion is the false dichotomy between “droplet” and “airborne” transmission that we use in healthcare settings (for simplicity of messaging, and because it has served us well for several decades—for reasons I’ll get back to later). This dichotomy divides application of transmission-based precautions between those pathogens spread via respiratory droplets, all of which must absolutely fall to the ground within 6 feet of the source, and those pathogens which become airborne, meaning they travel long distances on air currents, remain in the air for very long periods of time, and most importantly, can cause infection after their airborne sojourns if they find the right mucosal surface.

But we know (and WHO experts know) that there is no such dichotomy—it’s more of a continuum. At the very least there is a middle category, let’s call it Small Particle Aerosol Transmission (or SPAT). Many respiratory viruses (not just SARS-CoV-2) can remain suspended in aerosols and travel distances > 6 feet. As Jorge outlined, it’s probable that transmission events occur when these aerosols are concentrated in closed, poorly ventilated spaces or in very large amounts (e.g. a 2+ hour choir practice, a 3 hour indoor birthday party, a crowded bar). This may explain the superspreading events that drive a lot of SARS-CoV-2 transmission.

It’s important to distinguish SPAT from “classic airborne transmission” (let’s call it CAT). The CAT pathogens (TB, measles, VZV) have very different transmission dynamics than SPAT pathogens, as I outlined here (R0s of >10, household transmission rates of 50-90%). The distinction is important because for most healthcare epidemiologists, using the term “airborne” implies a common set of “one-size fits all” interventions to prevent transmission, interventions that require resource-intensive engineering controls and PPE requirements. It is not at all clear that such interventions are required to prevent transmission of SPAT pathogens. In fact, most evidence (and real world experience) suggests that they are not. This is why the droplet-airborne dichotomy has served us fairly well over the years—either because droplet precautions appear to be pretty effective at preventing SPAT, or because SPAT is rare even among those viruses capable of it.

I could say more about my feelings about aerosol-scientists criticizing epidemiologists and clinicians for having an “overly medicalized view” of the evidence, but I don’t want to be CAT-ty. I just want to end the SPAT.

So let’s redirect the discussion instead to: with the limited information we have, what additional interventions should WHO and/or CDC recommend for transmission prevention during the pandemic? Masks in crowded indoor spaces? Sure, but avoiding such spaces is preferred. Improved ventilation in all indoor environments? Absolutely, let’s get to work on that. N95s in the community? Don’t make me laugh, it might generate aerosols.* N95s for all patient care? Fair to consider, but by now we’ve gathered quite a lot of experience safely delivering care using existing WHO recommendations. And as Jorge aptly pointed out, “a debate only centered on whether respirators or medical masks are needed can distract us from the bigger challenges.” Indeed.

*Clarification as this comment, made in jest, has been misinterpreted.  N95 masks do not generate aerosols. They are unrealistic for community use, as they must be fit-tested and worn properly (even if we had an unlimited supply, which we do not). Nor are they, in my opinion, necessary for community protection. Face shields or medical/cloth masks are preferred for community use.

COVID-19 Can Have Airborne Transmission but You Don't Need to Run for an N95

This is a guest post by Jorge Salinas, MD, Hospital Epidemiologist at the University of Iowa Hospitals & Clinics. 

There is virtually no doubt that SARS-CoV2 is transmitted by droplets and contact. However, the debate continues about whether SARS-CoV2 can be transmitted through the air, in what epidemiologists call “airborne transmission.” As with most biologic processes, unfortunately this is not a dichotomy. Many (too many) factors play a role.

Population density matters. As people breathe, speak, sneeze, or cough we all produce many particles that have a continuum of sizes. These particles are unfortunately called too many names in the literature and the lay press (e.g., droplets, aerosols). Viruses and biologic processes don’t read textbooks. These particles can be large (what healthcare epidemiologists call “droplets”), medium size (no fancy name for them), and small (these are called “aerosols” by some but “droplet nuclei” by others). If we are near only one infectious person, the number of small particles (aerosols) expelled may not be enough to meaningfully contribute to infection. But if we are exposed to many infectious people at once, the number of small particles can increase. In such instances, airborne transmission in addition to contact and droplet transmission can play a role in outbreaks.

Patient characteristics are also tremendously important. Some may extrapolate that COVID is not as contagious or rule out the possibility of airborne transmission because of a paucity of hospital outbreaks, even if not following airborne precautions. If we follow the natural history of COVID, we now know that a person is possibly infectious 48 hours before symptom onset. Most people do not require hospitalization, and those that require hospitalization may be in later stages of the disease. We are learning daily that COVID, the disease caused by SARS-CoV2, is likely a continuum. Initially, the disease is predominantly caused by direct injury of the virus to tissues, but as days go by some patients will have immunologic or para-infectious syndromes that may require hospitalization. By the time a patient with COVID requires hospitalization, their infectiousness has likely decreased. It is now clearly recognized that presence of viral RNA does not equal risk of transmission in many cases.

The setting is also very important. How big is the space where the infectious person and their potential contact are located. If outdoors, the risk is tremendously decreased as air flows freely greatly decreasing the possibility of breathing “the same air.” Indoors, the number of air exchanges is very important: the more air exchanges, the lesser the likelihood of spread. Fortunately, most hospitals have already implemented an increased number of air exchanges likely decreasing the possibility of airborne transmission of pathogens in hospitals.

If airborne transmission plays a role in SARS-CoV-2 transmission, I believe it is predominantly in the early stages of the disease, in the viral phase. That may explain why most healthcare outbreaks have occurred in nursing homes and long-term care facilities. Not only because of potential infection prevention deficits but because patients are already in the facility when they become infectious. They are at the peak of infectiousness when in the facility. Hospitals on the other hand, will usually admit patients days or even weeks after the beginning of the infectious period, likely attenuating the risk of transmission in hospitals.

Recognizing that SARS-coV2 can also spread via small particles should not lead to panic. It should lead us to modify our behaviors in the community by avoiding crowded indoor settings, using universal source control with face coverings, and maintaining physical distance.

Modified from CDC.

In healthcare facilities, we need to continue educating stakeholders about the hierarchy of infection controls. Administrative and engineering controls are by far the most important measures. Decreasing population density, protocols for early identification and isolation of potentially infectious cases, especially those early in the disease course, and increased air exchanges are likely the most important measures. Personal protective equipment is also important. However, a debate only centered on whether respirators or medical masks are needed can distract us from the bigger challenges of administrative and engineering controls.

Reducing population density in healthcare facilities (patient census and personnel) can lead to increased safety but has a tremendous impact on population health (less capacity to take care of patients) and potential economic implications if healthcare personnel numbers are decreased. Engineering controls are also costly but fortunately most hospital design standards already address increased air exchanges compared to regular buildings and homes.

This pandemic has been challenging for all. COVID-19 keeps me humble as what I thought I knew yesterday may not be true today. Let’s all remain humble and nimble as we respond to COVID-19 in the community and in healthcare facilities.

Need a Face Shield?

Over the past few months, numerous people have contacted me to ask where they can purchase a face shield. I've assembled a list of some companies below. I'm sure there are many more, which I'm happy to add if you send me an email.

Standard Shields:

• 1800Shields
  
• 3DPPE
  
• Active Shield
  
• Actuated Medical
• Alisa Pan
  
• AltheaCare
  
• Amazon (multiple vendors)
  
• AMDA Lenses
• Armor Expert
• Arsenal
• ArtToFrame
• ASPEUS
  
• BDI Signs
  
• Be Ready
  
• Blue Bear Protection
  
• Bolle Safety
  
• Brooklyn Textiles
  
• Care Goody
  
• Counshop
  
• DebonAIR
  
• Disc Makers
  
• Distance Masks
  
• Dome Shield
  
• Eagle Eye Optics
  
• Ebay (multiple vendors)
• Eco FaceGuards
  
• Egis Viso
  
• FABBERZ
  
• FACEGUARD USA
• FACESHIELD
• Fire Farm
  
• Flowfold
  
• Fusion Lens
  
• Garizone
  
• GetEm Innovations
• GoodShield
  
• Google shopping (multiple vendors)
• Grace Technologies
  
• Hardwire
  
• Henry's Health Shield
  
• Humanity Shield
  
• i-Mask+ Face Shield
• Inspired Trends
• Iowa Made
  
• Kitsbow
  
• Laminati PPE
  
• Lifted Lenses
  
• Makers4Medicine
  
• Medspec Protect
  
• MI Face Shields
• Moda Loom
  
• MSP Aviation
• Noel Asmar
• No Headache
  
• OCTPLACE
  
• Shield48
  
• Sparx
  
• SRP
• Sveda Organics
  
• Technique Medical
  
• TheOne08
• TrueHero
  
• Unified
  
• Wet Shield
  
• ZVerse
  

Industrial shields:

• Jackson Safety Maxview
• UTM
  
• Uvex Bionic

Shields that attach to baseball caps:

• Armor Hat
  
• CapGuard
  
• Fresh Air Face Shields
  
• InstaShield
• Just Emporium
  
• RealShield
  

Hats with built-in shields:

• Considered Goods
  
• GiniGood
• Hairbrella
  
• Just Emporium
• Safety Hats
  
• Shein
  

Fun ones & kids' shields:

• ArtToFrames
• Boss Chick Life
  
• DEVO Energy Dome
  
• Disco Shield
  
• Shield Pals
• The Annie Store
  
• Zazzle
  

Shields designed to be worn with loupes:

• Dental Flex
  
• Loupe Lid
  
• NelDerm
  
• Ultra Light Optics 

Shields with goggles:

• Eagle Eyes

DIY Face Shields:

• Apple
• Instructables
  
• Michael's
  
• Quartz
  
• Woodbrew
  

Shield bulk orders:

• AcuShield
• Armor Expert
  
• carrKIT
  
• Cleveland Menu
• CROSSTEX
  
• Dr. Face Shield
• Egis Viso
  
• Feiereisen
• Helmy
• HexArmor
  
• High Ground Gear
• Homefront Rosie (a nonprofit that sells face shields & also donates faces shields to hospitals)
• Iowa Made
  
• RCO Engineering
• RUF Shield
  
• Trillium Now
• Upstaging
• Visipak
  

Lessons from a Pandemic: Part 2

Photo by Volodymyr Hryshchenko on Unsplash

Three weeks ago, I wrote a piece on the lessons I learned from the beginning weeks of the COVID-19 pandemic in Iowa. You can see that here. If any of you feel like I do, three weeks in COVID time seems like a year. It has the feeling of a chapter from Einstein's Dreams. In ordinary time my week has a rhythm to it, with different meetings and activities on different days. Certain nights we go out for dinner. Now, every day is nearly the same at work and after work. It's all COVID, all the time. I sometimes wonder what normal life will be like but it seems so distant that I find it hard to imagine. I know that at some point this will end but it doesn't seem near enough to be real. It's like being in a surreal time warp that could have been an episode from the Twilight Zone. OK, enough weirdness. Here are my latest lessons:

1. Working at home truly increases efficiency. For the first time ever, I worked at home for an entire week. Previously, I had never worked at home for more than a day, and only if I had a project that required intense focus or a need to get it completed quickly. I had multiple Zoom meetings every day and gave four lectures by Zoom. What I now realize is that the many interruptions in my work day, with all the starting and stopping and the re-start after every interruption really reduce efficiency. At the hospital most of my meetings involve a 5-10 minute walk each way and when you have numerous meetings that adds up. And along the way you stop for unplanned chats that increase walking time. I also feel the need to check in with people that I work with and discuss current work issues. That's a good thing, but I now have a better view of how all of this impacts my workflow. 
   
   
2. Medical care doesn't necessarily need to be face-to-face. Last week I had my first telemedicine clinic. I had done telemedicine inpatient infectious diseases consults for small community hospitals in the past but never outpatient clinic. It worked very smoothly. For most patients, particularly those with known problems, auscultation, palpation, and percussion don't add all that much. Once the outbreak is over, it will be interesting to see how many clinic visits return onsite. With advances in technology, patients can have BP cuffs that transmit readings, pulse oximieters, and even wireless stethoscopes at relatively low cost, making good assessment in the patient's home much more achievable.
   
   
3. Determining what is and is not an aerosol-generating procedure (AGP) needs to be thoroughly explored in future research. See these two excellent posts by Tom Talbot here and here to read more about AGPs. 
   
   
4. In times of crisis, healthcare workers' risk tolerance is greatly reduced and risk perception is not always rational. This is natural given all of the information on the outbreak, much of it scary, that comes at us 24/7. There is a cry for zero risk, even though that is likely not achievable. In an effort to advocate for their constituencies, professional societies have added to the anxiety and created more demand for resources that are already scarce, such as testing supplies and personal protective equipment.  
   
   
5. Once and for all, we need to determine the utility of every item of personal protective equipment for various types of pathogens. This will require federal funding to do the needed research. New designs should be evaluated and current PPE improved. 
   
   
6. The focus of infection control and prevention research has been too focused on bacterial pathogens. Looking at journals from the last decade, one can see that most of the papers are focused on drug-resistant bacterial pathogens. These organisms pose little risk to healthcare workers. As above, federal funding will be needed to accomplish the needed work.
   
   
7. CDC has not been helpful by producing confusing information that is not practical, and SHEA and APIC have offered little to no guidance at a time when it is most needed. In contrast, the World Health Organization has produced guidance that is based on sound logic and written in a very clear manner. 
   
   
8. Anthony Fauci is a hero. Where would we be without him? Don't think about the answer to that question. 
   

More to come. Stay safe, everyone!

Mike

  

The Face Shield Strategy: Moving to the Community

REUTERS/Athit Perawongmetha

With the assistance of a great supply management team, we have been able to outfit all of our clinical staff with face shields. See here for our rationale and implementation. Acceptance by healthcare workers has been good and compliance is easy to visually monitor. Our message is that the shields are to be worn at all times except when eating or when in a room alone. Shields alone are worn for non-COVID care. For the care of COVID patients, masks are added beneath the shield, except in the instance of aerosol-generating procedures, when N95 respirators are worn beneath the shield. 

This week CDC recommended the use of cloth masks for all persons in public settings. Although cloth masks are better than nothing, depending on the material, the filtration efficiency varies, and they can become contaminated. Moreover, adjusting the mask increases the frequency of touching the face, which can lead to autoinoculation if the hands are contaminated. We're not very excited about this strategy. However, we believe that face shields offer a better solution for the public. Dan and I laid out the case for this in an OpEd in the Des Moines Register this week. 

The advantages of face shields are their durability allowing them to be worn an indefinite number of times, the ability to easily clean them after use, their comfort, and they prevent the wearer from touching their face. Importantly, they cover all the portals of entry for this virus--the eyes, the nose, and the mouth. Moreover, the supply chain is significantly more diversified than that of face masks, so availability is much greater. Large companies, such as Apple, Nike and John Deere, have converted production lines to make face shields. Smaller companies, such as Upstaging, have as well. Upstaging is selling shields to consumers as well as hospitals. (I ordered some from them and received them in less than 24 hours.) Because the design of face shields is simple, massive production should not be difficult. Individuals and groups are making them via 3-D printing, and they can even be made from materials that are readily available from stores that sell office or craft supplies. Our goal should be to have a face shield for every person in the country. It should be worn anytime a person leaves their home, while in any public place, and even at work. From news reports, it appears that face shields are already being more commonly worn in other nations, particularly in some Asian countries. 

Some argue that face shields may not prevent infectious aerosols that could be propelled around the edge of the shield. However, it appears that with this virus, transmission occurs mostly via droplets that do not have the ability to move in air currents and waft around the shield edges. But importantly, if everyone is shielded, these aerosols would need to move around the shield of the infected person and then waft around the shield of the uninfected person for infectious droplet nuceli to land on their face. The probability of this happening seems low, particularly since persons who are symptomatic and coughing should not be leaving their homes anyway. And hand hygiene still needs to be stressed to prevent autoinoculation. 

Some are critical of any strategy that isn't perfect. But let's think about the influenza vaccine. Although the effectiveness varies from year to year, on average it's 40%. We push this vaccine hard in the hospital and in the community. Could we expect that face shields are at least 40% effective in reducing the transmission of COVID-19? I think so. Universal shielding would bend the curve more quickly and accelerate the ability to reduce social distancing and restrictions on movement. 

Face shields are a simple solution that if implemented universally would have a major impact on public health. Until we have a vaccine, this may be our best intervention for preventing transmission in the community.

Addendum:  See our viewpoint, Moving Personal Protective Equipment into the Community, on this topic in JAMA.

Airborne vs Droplet: Turbulent Gas Clouds of Opinion!

There’s much about the COVID-19 pandemic that is unprecedented, at least in my lifetime. One aspect is very familiar, though: arguments about the primary mode(s) of transmission of a newly emerging respiratory virus.

Much of the problem stems from our need to divide transmission modes into simple categories in order to apply prevention measures effectively. When someone calls the infection prevention program to ask about precautions recommended for virus X on the respiratory viral panel, it's not helpful to begin the conversation by saying, 

“well, you know, droplet and airborne transmission is not really a dichotomy, it’s more like a continuum, and there are a lot of factors at play—can we talk in more detail about the patient’s condition, what procedures they might be undergoing, and whether they might break out in song during routine patient care activities?”

One recent review you may find useful was published in Current Opinions in Infectious Diseases in August of 2019 by Shiu, Leung and Cowling (talk about great timing…). A very important point made in this piece is that viral nucleic acids and (less often) viable virus can be found in air samples--including from healthcare environments--for influenza, RSV, adenovirus, rhinovirus, and other coronaviruses. So reports about airborne SARS-CoV-2 (which will keep coming out in both pre-print and peer-reviewed literature) are not surprising. Nor do they answer the most important practical question about SARS-CoV-2 transmission:

Is airborne transmission a major mode of COVID-19 spread in community and in routine (i.e. no aerosol-generating procedure (AGP)) clinical settings?

My view is that we should consider the epidemiology of COVID-19 thus far in the pandemic, to determine if transmission patterns are more consistent with that of other common respiratory viral pathogens, or more consistent with that of the agents we classically consider to be transmitted by the airborne route (measles, VZV and M. tuberculosis). We could compare, for example, attack rates in various settings (household, healthcare, public), and the infamous R0 (expected ‘average’ number of secondary cases from a single infected individual in a susceptible population).

For COVID I’ll point to two careful contact investigations—this one of the over 400 close contacts of the first 10 travel-related COVID-19 cases in the US, and this study from Guangzhou, China, which was ten-fold larger (4950 close contacts to confirmed cases). The US study examined symptomatic secondary attack rates, and the study in China did serial RT-PCR on all contacts in addition to monitoring for symptoms. The findings are remarkably similar: highest attack rates are among household contacts (10.5% in US, 10.2% in Guangzhou), with extremely low rates of transmission among healthcare or community contacts (zero in US study, 1% among healthcare contacts and 0.1% among public transport contacts in Guangzhou). As for the R0, which of course varies as a population begins prevention approaches, the best estimate in my opinion is the tragic natural experiment performed on the unfortunate passengers of the Diamond Princess: during the early stage of the outbreak the R0 was 2.3.

For measles, the R0 is 12-18 and the secondary household attack rates are >= 90%. 

For VZV, the R0 is ~10 and the secondary household attack rate is 85%.

For TB, the R0 for smear-positive untreated TB is up to 10 (per year) and the secondary household attack rate has been reported to be >50%.

Based upon the above, I’m confident that SARS-CoV-2 transmission is similar to that of other respiratory viruses we are used to encountering—for which experience suggests droplet + contact spread to be the primary route of transmission. The trick is determining under what conditions a higher-risk aerosol might be produced (i.e. what is our list of AGPs? See here and here, if you dare!).

Does this mean that every respiratory droplet falls to the ground immediately and within 6 feet of a coughing patient? No. Dr. Lydia Bourouiba has an excellent piece in JAMA about the role of “turbulent gas clouds” in allowing droplets to travel further, and to remain in the air longer, than our traditional “droplet-airborne” dichotomy considers. In my view, this kind of droplet + "gas cloud" production mostly contributes to the extensive surface contamination that results in the highest risk of transmission being among close household contacts.

AG(P)itation, Part Deux

Since my post last weekend, I now have found the term that, once this is all over (and it will be over someday, my friends), will send me into flashbacks and result in me sitting in the corner, rocking back-and-forth, saying "Please, Mommy, make it stop."  "Aerosol-generating procedure." AGP for short. 

In the last few weeks, the items that healthcare teams across the U.S. and professional societies have insisted are AGPs have included, but are not limited to, the following:

• Laboring patients in second or third stage of delivery 
• All TEEs ("because might accidentally enter the airway like a bronch")
• EGDs (The new AGA guidance states: "To estimate the risk of viral transmission in endoscopic procedures, we examined data evaluating non-GI aerosolizing-generating procedures such as bronchoscopy and tracheal intubation. Our search strategy did not yield comparative studies on the degree of aerosolization with upper or lower GI endoscopy compared with bronchoscopy or tracheal intubation. However, we assume that insertion of the endoscope into the pharynx and esophagus is likely to be associated with a similar risk of aerosolization of respiratory droplets to that of bronchoscopy.") 
• Orthopedic procedures with drilling of intramedullary bone
• Any surgery that goes anywhere near a sinus (All ophthalmologic procedures, any craniotomy, etc)
• Any dental procedure
• Cardiac cath lab procedures where the patient is "found down" (their MI might have been brought on by COVID-19)
• All neurosurgery because the patient's face is right in the surgical field
• All electrocautery (guidance that was courtesy of the American College of Surgeons that has now been removed from their guidance page)

Some such requests are based primarily on concerning yet truly anecdotal stories from other countries that claim a specific specialty is at "highest risk of contracting COVID." Often these are extended to all patients due to the possibility that an asymptomatic patient could be a source of spread, drawing the thread from detection of SARS-CoV-2 at high levels in the upper airways in asymptomatic patients to detection of viral RNAemia in a minority of hospitalized highly symptomatic patients to note theoretical risks. In many of these instances, the proposed risk of "aerosol" exposure is due to facets of the procedure that would have existed long before COVID-19 and, if true, should have warranted use of N95 respirators as part of Standard Precautions for these procedures for years.  The added interjection of professional society guidance that understandably advocates for the healthcare workers in their field but doesn't contain any evidence base to support claims that x or y is an AGP that leads to increased risk of pathogen transmission requiring an N95 also creates marked discomfort for infection prevention and operational teams on the front line, when faced to assess risk and allot precious PPE. As a colleague told me last week, "No society is going to say, 'Hey, we're cool.  We'll just take the masks.'" I imagine, if we had unlimited PPE, this wouldn't be an issue, as we all want our colleagues to be protected and feel safe. The reality is PPE is a scarce resource, and one that we have to use our science to guide decisions.

The best thing about this issue is that hopefully Dr. Babcock will get more funding for her research to help address these questions. When all this is over, I guarantee you that the term "AGP" will cause me, and I imagine many of you, to run the other direction . . .  Stay healthy and sane everyone!!

A Face Shield Strategy to Reduce COVID-19 Nosocomial Transmission

In previous blog posts, I mentioned the implementation of face shields to prevent nosocomial COVID-19 infection. Over the past few days, I have received many questions from people across the country, so I thought it would be useful to pull everything together in a single post and add some details.

Rationale

As we began to prepare for the pandemic, we assessed our inventory of personal protective equipment (PPE). However, knowing current inventory levels alone is not useful. It's deceiving when you see PPE inventory levels of several hundred thousand items. How could we ever run out, right? This is why your inventory levels must be evaluated in the context of normal demand. Your supply chain folks should be able to tell you how many PPE items are normally used on a daily or weekly basis. Next, you need to determine your expected demand for the outbreak. There is no right answer here as there are too many unknowns. You'll just need to make an educated guess. We determined that our critical level of each PPE item was 12 weeks (84 days) at four times normal demand*, although you could argue that this is an underestimate. Next our supply chain group developed an interactive spreadsheet with each row being a PPE item, and columns showing current inventory; normal demand per day; and days of stock at normal demand, two times normal demand, and four times normal demand. The final column (days of stock at four times normal demand) is color coded as follows: red <84 days, yellow 85-111 days, green >112 days (16 weeks). Once this is done, you will likely be surprised to find that what seemed like an abundance is really not so. When evaluating your levels, you also need to consider that some items are on allocation and you can expect to receive periodic shipments, while others are simply stocked out with no promise of future deliveries.

After reviewing all of the above, the most worrisome thing for us was an inadequate supply of face masks (<84 days at four times normal usage). My biggest fear was that we would overuse them early in the outbreak when few COVID patients are hospitalized, then have none after the surge of COVID inpatients arrived. Many hospitals had extended the use of face masks beyond a single patient encounter, which is a reasonable decision in this time of shortage, but we know that face masks lose their effectiveness when they get wet. Some began to use cloth masks, which is also a problem. So I began to wonder whether face masks could be replaced by face shields.

Why face shields?

• They provide greater facial surface area coverage than face masks by protecting all the facial mucosal surfaces from infectious droplets. 
• Given that the eyes are protected, we can eliminate the need for goggles when a face mask is worn. And we know that healthcare workers are really bad at wearing eye protection.
• They prevent you from touching your face. One of the major drawbacks of face masks is that some people will touch their faces even more to adjust the mask and this poses a risk for autoinoculation by contaminated hands.  
• Face shields are durable, can be cleaned after use, and reused repeatedly.
• Many people (myself included) find face shields more comfortable than face masks.
• Communication is better with shields than with face masks as your face is visible to patients and coworkers. 
• If all of your healthcare workers are shielded, social distancing becomes less important.
• And importantly, this is a device that is diversified across other industries. There is greater availability since the medical supply chain is so stressed at this time.  

Are there any disadvantages compared to face masks? The only one I can think of is the possiblity of a droplet coming in an upward trajectory going under the bottom edge of the shield. Although the probability of this is small, this can be minimized by having the shielded healthcare worker flex their neck when standing over the patient (for example, when performing a physical exam), bringing the bottom edge of the shield closer to the HCW's torso. Moreover, when doing a procedure that normally requires a face mask, we recommend that a mask be worn under the shield anyway. 

A few people have asked what is the evidence that face shields can replace face masks, and those particularly inclined toward methodolatry (the profane worship of the randomized clinical trial as the only valid method of investigation) continue to demand that face shields not replace face masks. Do I have evidence? No. To me, this is just plain common sense--we have a product that is reusable, cleanable, covers more of your face, decreases the risk of autoinoculation, and keeps us from burning through our mask supply. We have hospitals in the US where nurses are using bandanas to protect themselves. In this extraordinary time, I can live without a clinical trial.

Implementation

We quickly found that face shields marketed for medical uses were stocked out. One of our pharmacists went to a local hardware store and found shields used for grinding. We then explored vendors that supply hardware and agricultural products (see more here on the purchasing process). In addition, the University of Wisconsin has a great website that includes diagrams for construction of shields, and Johns Hopkins has a "recipe" available that can be used to create 50,000 shields. We placed the Wisconsin diagrams on the hospital website and several manufacturing firms responded that they could fabricate them for us. In addition, we have had some designed and produced by people interested in 3-D printing. One of our physicians, modified the Johns Hopkins' information and has her kids at home making shields. We also placed on our hospital's website a request for donation of face shields that people have at home, and we received many donations. It has really been a community effort. As our supply of shields grows daily, we deploy them throughout the medical center. At this point, the shields are handed off from one worker to the next as their shift ends, but our ultimate goal is for every person to have one for their personal use. 

Here are the instructions we give to our staff on when to use face shields:

• Wear the face shield with every patient encounter (COVID and non-COVID patients) over a medical mask. Think of it as a new component of standard precautions--every patient, every time.
• For COVID patients (confirmed or suspect), if an aerosol generating procedure is being performed, wear the face shield over an N95 respirator.

To help introduce the concept to our workforce, we produced this video:

We still have some details to iron out, such as the best product to clean the shield, since some products damage polycarbonate. We have had some of the shields break, so fabricating replacement shields to repair them is ongoing. 

Lastly, I have had a number of people who want to purchase their own shield ask me which one I recommend. Over the past two weeks, I have tried many models and have become a face shield connaisseur. If you want to buy your own, I think the best is the Uvex Bionic S8510 made by Honeywell (shown in the photo to the right). It is more sturdy than many other models, provides greater facial coverage (extends laterally on the face to your ears), and is comfortable. What really sets it apart is the V-shaped, downward projecting bottom border of the shield. This allows it to sit close to your upper torso, minimizing the risk of upward trajectory droplets. As an added bonus, from a sartorial standpoint, you'll look top-notch in this one! It's the kingdaddy!

This is probably more than you ever wanted to know about face shields. But it's a crazy time and we hospital epidemiologists are doing things I could have never imagined just a month ago. The bottom line is that by employing face shields we are able to protect our workforce while extending the duration of time that we will have face masks available.

Stay safe and be well!

Mike Edmond

*Addendum: A hospital in New York reported 15-30 times normal demand for face masks.

AG(P)itation

(Apologies to Mike - we usually don't like to step on each other on the blog, but I missed he'd just published another great post!  So don't miss it here!)

So this week, the reality of what's coming started to dawn on many at the medical center. As we start moving from the preparation to the treatment phase of the pandemic, more people have been pulled into the realities of caring for suspected and confirmed COVID patients . . . and stories abound from around the U.S. about how a lot of them have some very strong opinions about PPE:  A healthcare worker who showed up to work in full Ebola gear (no, I'm sure the co-workers felt safe in their "flimsy" masks).  Entire units who mandated masking of everyone after a co-worker was diagnosed with COVID (and had not worked with symptoms).  The sudden interest in and expertise about asymptomatic transmission by folks who never worried about coming to work sick with other viruses before.  Adding to the confusion are the contradicting images (full Tyvek suits in China), messages (a Power Point describing Wuhan experiences that notes SARS-CoV-2 can spread "through eyelashes and hair"), and, sadly, guidance from various authorities:

• OSHA: "Those who work closely with (either in contact with or within 6 feet of) patients known to be, or suspected of being, infected with SARS-CoV-2, the virus that causes COVID-19, should wear respirators."
• CDC: First, the recommended protection included a respirator for all types of patient care.  Then this was revised to: "Put on a respirator or facemask (if a respirator is not available) before entry into the patient room or care area. N95 respirators or respirators that offer a higher level of protection should be used instead of a facemask when performing or present for an aerosol-generating procedure. . .When the supply chain is restored, facilities with a respiratory protection program should return to use of respirators for patients with known or suspected COVID-19."
• WHO, Canadian Health Authority, and an increasing number of state health departments, including Tennessee:  Gown, gloves, facemask, eye protection (goggles or face shield) unless performing an aerosol-generating procedure, and then use a respirator or PAPR instead of the mask.

I definitely understand and support the need to be cautious, especially when it's early in a new pathogen outbreak, and the protection and safety of healthcare personnel (HCP) has been a major concern of mine and the focus of my career.  But one can easily see how the seeds of confusion have been sown among our HCPs regarding PPE.

No issue has been the bane of my work this week than "aerosol-generating procedures" or AGPs, and as I tried to dive into the science behind these recs, I came away even more confused.  A few quick learnings and thoughts on this issue:

• The term "aerosol" means a very different thing to a true aerosol scientist (whom I imagine I will offend with much of my own ignorance here) and most lay medical people:  To the former, an aerosol is a smaller particle (smaller than a droplet), the smallest of which require a higher level of filtration to protect HCP (as in a respirator).  To the latter, any visible drop of fluid, liquid, spit, etc. is an "aerosol" ("I can see it flying through the air!!"), and as such their perception is that the official lists (more on those in a bit) of AGPs are lacking.  
• The various lists of what might be an AGP vary by organization and even changes within a single organization's guidance.  Some include nebulized medications. Some, like WHO, had nebs on one version of the list in 2007 but removed them in 2009. A brief summary below:

     

• The actual science on what is an AGP and, more importantly, whether they confer a higher risk of transmission of infectious agents is a) very difficult to illustrate (often relying on retrospective recall of patient care activities in infected and non-infected HCP), b) involves some logistically challenging studies (ask Dr. Babcock), and c) has many confounding factors (individual patient issues, use of PPE, etc.).  I refer you to a few excellent papers on the topic HERE and HERE (shout out to our favorite blogger!).  Also see this nice summary in the lay press HERE. 

I imagine, if we all shared our lists of AGPs, there'd be wide disagreement (which is why I didn't tell you mine). Some will have nebulized medications (which always throws the peds clinics into a frenzy). Some don't.  CPAP/Bipap?  Maybe, but the few studies that have examined this often just say "non-invasive ventilation," and 1 study in SARS had a single patient infect 22 HCPs as a driver of that risk.  Is nighttime Bipap setting on the vent the same as rescue Bipap in impending respiratory failure (where there may be more suctioning and bagging of the airway?).  Open suctioning of the airway?  Just try to find any further description of that generic and broad term in any of the guidelines or evidence base. Is a brief (few seconds), pharyngeal suction an AGP? Is it really similar in risk to a deep, persistent need to suction copious lower airway secretions? Clearly no, but they're all "open suction of the airways." I think what we're seeing is that a simple term or list of procedures that is provided in guidance without strong evidence or out of an abundance of caution can have major logistic and psychological impact when trying to implement on the front line.  Also, without more clarity (and more funded science on this topic!), we end up potentially using valuable PPE that was not warranted if no risk exists. 

I'll end by saying, sadly, this is not the first time we've dealt with this issue. For those of us who were hosp epis during the H1N1 pandemic, this exact conversation occurred, albeit with less intensity as the wave of illness didn’t flood the hospitals as much as expected. Our frontline healthcare workers are putting themselves at potential risk by caring for these patients, and they are understandably anxious and scared. Conflicted and confusing PPE recs do them no service, and guidance not rooted in science that leads to inappropriate use of PPE may lead to shortages down the road and more exposed HCP. This pandemic has already started, but perhaps we can finally learn and have more funded science to provide clarity and consistency on these issues that account for the real world nuances of delivery of healthcare. Failure to do so merely puts our HCP at greater risk for the next new pathogen.

Lessons from a Pandemic

Photo by Martin Sanchez on Unsplash

We are in the early stages of the COVID-19 pandemic, but it's already very clear that the Infection Prevention community in the US has never faced such an enormous challenge. Reflecting back on the past two weeks, we have learned many things that will make us better prepared for the long term. My goal is to keep track of these in this blog. So here we go:

1. We are far too reliant on single-use disposable products. Having a large supply of cloth surgical gowns and isolation gowns that can be laundered is essential. I'll comment on disposable face masks below. Less reliance on disposables will also be better for the environment.
   
   
2. The supply chain for medical products needs geographic diversification. It wasn't all that long ago that we had numerous shortages of medications and IV fluids due to the hurricane in Puerto Rico, and now we have this crisis due to concentration of manufacturing in China.
   
   
3. Just-in-time inventory management is not a great idea in healthcare, particularly when the supply chain is rooted in a single geographic area. Most hospitals, especially larger ones, have some strategic stockpile of products, but it's unlikely that any have inventory levels to manage an outbreak that lasts for many months. Hospitals and government (both at the state and federal levels) have a lot of work to do in this area.
   
   
4. We have a new standard for evaluating personal protective equipment (PPE). In the old days (like last year), the standard for evaluating a new PPE product was: is the new product better than currently available products? Today's standard is: is the new product (let's say a bandana to cover your nose and mouth) better than nothing? I'll push that a little further and argue that the new standard should be: is the bandana no worse than nothing? Healthcare workers are very afraid, and I'll freely admit that I'm one of them. We all want to proactively protect ourselves. Even if the bandana is minimally protective, if it provides some level of psychological safety, we need to respect that and allow our workers to wear "homemade" PPE.
   
   
5. Going forward, the new attire standard for healthcare workers should be hospital-laundered scrubs. These should be donned after hospital entry and doffed prior to leaving. This will require that hospitals construct adequate changing and shower facilities. And scrubs should be coupled with a bare-below-the-elbows approach to patient care.
   
   
6. To the greatest extent possible, no-touch technology should be built into hospital design. Sensors that detect a hand wave for door opening are a great advance.
   
   
7. Face shields should and will replace face masks. They provide greater facial coverage and make it physicially impossible to touch your face. And I find them more comfortable than face masks. Sturdier models can be wiped down and reused. I suspect that every healthcare worker will purchase one, just like they purchase a stethoscope. For this outbreak, I am advocating that face shields be worn for every patient encounter since many patients with COVID-19 are minimally symptomatic. It should become a new component of standard precautions.
   
   
8. The community really wants to help us. I have recieved numerous forwarded emails from colleauges who have friends and relatives who want to sew masks or isolation gowns, donate their face shields and N95s, or whatever they can do to play a part in making things better. This is beautiful.
   
   
9. Infection Preventionists are true heroes. They are working around the clock to keep hospitals functioning. These people are the salt of the earth. They work in the background with little recognition and are some of the most committed people I have ever met. Thank you, thank you, thank you!

These are my initial thoughts. More to come. Get some rest and stay well!

Mike Edmond