Week of April 20th COVID-19 Update

April 20, 2020

Currently, we are in a transition period as various governments around the world wrestle with the details of removing restrictions on the economy without allowing a resurgence of cases.

Additionally, we are just now beginning to get some details on how many people in various communities have been, at some point, infected with the virus – knowingly or not – and that will help us in determining reopening strategies, including testing.

Last week, I talked about the Hammer and the Dance: The Hammer being tight restrictions on movement and economic activity and the Dance being the next phase where we are able to tailor restrictions on both in order to get the economy moving again while still being able to tighten up if needed.

Moving Forward

Currently, about 60% of the entire world’s population are under fairly heavy restrictions. Obviously, that cannot continue indefinitely as that literally would make the cure worse than the disease.

Both the World Health Organization and the US Centers for Disease Control and Prevention are in agreement on the basic criteria for moving from the Hammer to the Dance:

  • Meaningful reduction in the number of new cases.
  • A local health system no longer under stress and with a capacity if there is an uptick in cases.
  • Adequate capacity to identify, quarantine, and do contact tracing on any new cases.

Very importantly, there is increasing recognition that this must be applied on a region by region basis. In other words, what is best for New York City is not the same as what is best for a smaller city in Central New York.

A corollary to this, however, is that this could conceivably speak to maintaining some degree of restrictions on non-essential international or interregional travel.

As many regions, notably Singapore and Hong Kong have determined, once local case numbers are under control, one of the biggest risks is new cases brought into the region through travelers. Importantly, it is reasonably clear that the movement of goods between regions does not promote the spread of disease.

We spent a good deal of time talking about testing last week. This is still a big issue both at the national policy level and at local family and business levels.

Antibody Testing Update

First, an update on antibody testing. The first results on antibody testing of communities are starting to come in, and most communities are seeing around 5% of the population with evidence of exposure to the virus. Additionally, as I noted last week, we do not have data yet on what level of antibody protection is needed to imply resistance to future infection. Putting these two things together tells us 3 things:

  • Antibody testing is not going to give us useful data for identifying whether you are relatively immune or not both because of not knowing the immunity level, but also because at that lower level of community exposure, the result of the test is not going to be accurate enough to make any conclusion that you can act on.
  • Herd immunity is probably not going to play a major role in getting us through this until we have a vaccine. Some of the more hard-hit areas, like northern Italy and New York, may see much higher rates of exposure, and these assessments may be somewhat different in those areas, but for the bulk of the world, there is no good reason to get antibody testing except as part of a community study process.
  • The Point-of-Care testing kits that are billed as being almost as simple as home pregnancy tests are not accurate enough to make any decision on your immunity, so there is not much use for them. In the future, as we have better data on what to “set” these at, that guidance will change, but for now, the only thing they tell you is that it was more or less likely that you have been infected with SARS-CoV-2, and NOT that you are immune. Caveat Emptor!

Testing Update

On individual testing for the presence of the virus, we did some further investigation on the high false-negative rates seen in many reports.

The actual PCR tests are highly accurate, but the process of getting a meaningful sample is difficult: The virus reaches high levels in the respiratory tree at different times, so it’s very possible for a nasal swab, for example, to miss an infection that has moved further down into the lungs.

Additionally, the test itself is very dependent on the person taking the test.

For these reasons, testing people who are not symptomatic or who do not have a good exposure history has a very high false-positive and false-negative rates. Unlike some other diseases, screening completely asymptomatic people is not helpful.

Testing of people with symptoms, however, when done correctly, does have good accuracy and will be a critical part of the control program as we move into the next phase of dealing with COIVD-19.

Slowing down the virus

Those of you who have been following my updates will remember that early on I discussed three speedbumps that might help us slow down this virus.

The first is the onset of spring and summer. Just as with flu, it’s not primarily the temperature that helps us here, but multiple factors, including school, being out, people taking vacations and thereby decreasing population densities in their offices, better weather getting more people spending more time outdoors, and more sunlight which may help kill viruses more effectively because people are spending more time outdoors. This is all based on other respiratory virus data, though, so we will be following this together.

The second speed bump is the development of anti-viral drugs. The most discussed of these are Chloroquine and Hydroxychloroquine. There is still no solid data either way that they work or do not work, but a fair amount of anecdotal data that when used early in serious disease they can reduce the need for a ventilator. Whether or not they have more general utility is still up in the air.

Aside from those, there are over 100 studies of potential anti-COVID medications in process, but nothing yet that is definitive.

Finally, the last speed bump is vaccines. Vaccine development continues with no breakout findings or studies, although there are a number of candidate vaccines still on track for the 1st quarter of next year. Much can happen between now and then in either direction.


By now, people are becoming more comfortable with the idea of masks. Please remember to share with people that, generally, masks are mainly to protect others from you if you have COVID-19 and don’t know it. They do not protect you from disease. If you are in situations where you are nowhere near others, such as when exercising outdoors, or at home, or hiking in the woods, the mask is not needed, but the new social norm is becoming an expectation to show concern for others by wearing a mask in any situation where you are likely to come within 6’ of others.


Finally, an issue that has been coming up this week is that many cleaning companies are pushing that they need to do a HAZMAT style cleaning whenever someone has been diagnosed with COVID-19. CDC has been very clear on this in that cleaning just requires wearing gloves and a cover gown. Not a full HAZMAT suit. In fact, the only reason for a facemask is if that is becoming indoor standard in that area or if using cleaning products that recommend respiratory protection, which is neither common nor needed just for COVID-related purposes.

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