Resurgence of COVID-19 Cases in the U.S.

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June 25, 2020

Resurgence of COVID-19

A major concern this week is the resurgence in cases of COVID-19 in many states along the country’s southern tier.  Very importantly, as the United States reopens its economy, it does not mean that the county is returning to where it was in March. 

  1. For many reasons, the US is once again becoming the “hot spot” in the developed world.  At least for now, if anyone is asserting a specific reason, be aware that they may have a non-scientific reason behind this assertion, as the data is just not there to support any compelling narrative. Theories currently in the discussion are: 
    • Increase in testing
    • State reopenings
    • Memorial Day weekend
    • The younger population being more cavalier about stay-at-home orders
    • Heat driving people indoors in southern states
  2. This is not just April all over again.  Numbers are up for many reasons, but not all of these reasons represent actual increases. The shifted age range for diagnoses means that we will not likely see widespread pressure on our healthcare system, the threat of which was the main driver for the shut-downs in the first place.
  3. We’re not out of the woods:  Physical distancing, staying home when you are at-all sick, wearing masks in public when you‘re in close proximity to others, protecting at-risk populations, and generally using common sense at stores, restaurants, etc. can all contribute to holding the rates down and keeping us from threatening the healthcare system in any meaningful way.  This, in turn, combined with age shifts will reduce scientific pressure to re-institute stay-at-home orders or other holds on commerce.

Air Travel Highlights

As stay-at-home orders have expired, many people are getting a wanderlust. While I did discuss this a few weeks ago, now that Air travel is beginning to pick up, we are receiving questions on air travel and risk again.  First, and very importantly, air travel has not been a major driver of the pandemic.  With increasing recognition of the importance of airborne infection as the primary way people get infected, you would think that being in an enclosed metal tube cut off from the external environment would be exactly the condition that would lead to infections.  I had the opportunity to learn about this in detail when I worked at the Department of Homeland Security.  Modern airliners are designed to have airflow that does, in fact, incorporate external air, as well as drive particles to the floor rapidly and then recirculate the air through filters that are changed at regulated intervals.  All airlines are now asking passengers health screening questions and requiring passengers to wear masks.  All of this together decreases the important risk of airborne infection.  Next, the airlines have instituted increased cleaning programs to reduce the chance of infection on surfaces.  Additionally, for now, the number of people on planes is decreased so the population density is decreased.  So, what can you do to further reduce your risk?  Get the best seats, bring your own wipes and carefully wipe the surfaces around you such as tray tables and armrests, and do not crowd the aisle to get out. Stay in your seat area until those in front of you deplane.  


PCR testing (swabs) is for diagnosing infection.  There are both rapid tests on office-based machines that are reasonably specific, but they still have an unacceptably high false-positive rate.  This means that if you have symptoms and go to a clinic and they run a result in 20 minutes, a positive result is a true positive with a high degree of confidence, but a negative result should be confirmed by a lab-based test. 

3 important caveats on testing for the presence of COVID-19: 

  1. There is only marginal utility in using these tests to rule out infection in an asymptomatic person.  If you were exposed to someone diagnosed with COVID-19 do not feel like you should run out immediately and get tested.  A test is only positive in the two days before you would get ill and that could be anywhere from 3 to 14 days after exposure.  So, testing randomly after exposure does NOT rule out infection. PERIOD.
  2. If you have been diagnosed with COVID-19, a swab test to make sure your infection has cleared is not useful.  Non-infectious particles of the virus can remain in your nose for up to a month after infection, but if you do not require hospitalization, you are reliably non-infectious 10 days after symptoms began.  Time is a better gauge than testing.
  3. Antibody testing has no role (except in very limited hospital cases) in telling you if you are infected and/or infectious.  NONE.  Antibody testing only tells you that you were infected sometime in the past.  We believe that you are more likely to have some immunity if you are antibody positive, but CDC and World Health will not commit to that with the current tests.

Personal Protective Equipment

Masks are still the mainstay of protection.  I am seeing many ads for masks that incorporate face shields or face shields that cover your whole face.  The only thing they really add is protection against direct spray as in when someone coughs or sneezes in your face.  Generally, that is uncommon. So, yes face shields can reduce risk slightly, but only slightly.

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