The Testing Lag

Remember that right now, the only way a case can be “confirmed” is if testing at CDC (by RT-PCR or viral culture) is positive for the swine-origin influenza virus (S-OIV—yes, that’s the new abbreviation and I’m sticking to it this time!). The cases that are being tested today will not be reported as confirmed cases until Friday at the very earliest (collected, sent to state lab, found to be influenza A but not typeable by state lab, sent to CDC, and tested). The turnaround will be shorter once the testing kits from CDC go online at state and other labs across the country.

What this means is that in addition to the 91 cases in 10 states that are now being reported, we can assume that S-OIV is now widespread. As more cases are reported with no links to Mexico or to other confirmed cases, the epidemiologic criteria for testing outlined in prior posts becomes increasingly obsolete. Testing will become more and more widespread, and case counts will skyrocket. The epidemic will appear to be expanding rapidly, but most of the changes will reflect increased testing and recognition of prior spread. We won’t know what is really happening now (in real time), for at least a couple weeks. I believe we’ll see more deaths and severe clinical presentations, but that the current epidemic will fizzle out over the next month—to return in the Fall as one of the circulating seasonal strains. Hopefully there will be an effective vaccine by then.

In the meantime, we need to prepare for more pessimistic scenarios than the one I believe to be most likely.


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