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!!