Why so many people are asymptomatic to COVID-19?

The response to COVID-19 and the basis for policy decisions can be summed up as TEST! TEST! TEST! The assumption is that by conducting antibody tests we can determine who currently has COVID-19 and who has previously had COVID-19 and is currently protected and not a spreader of the virus. The problem is that the antibody tests are proving to be problematic. Research indicates that the timing of the test is vital; use them at the wrong time and they don’t work. We don’t really know how accurately they identify COVID-19 in people with mild or no symptoms, or tested more than five weeks after symptoms started. This begs two questions:

  1. Why?
  2. What can be done about it?

New research suggests that some of us may be partially protected due to past encounters with common cold coronaviruses. It is increasingly obvious that a very high number of infected people present few or no symptoms. At a homeless shelter in Boston 88% of the infected residents had no symptoms. At a poultry plant the figure was 95%. If confirmed, the high rate of asymptomatic infection would be a good thing for both individuals and society as a whole.

Not-so-novel coronavirus?

We have assumed all along that the COVID-19 is “novel.” I.e., that it’s new to the world. If so, people’s immune systems would be completely defenseless and therefore unable to fight the infection. However, one possible explanation for the high number of asymptomatic cases is that COVID-19 is not a novel virus after all. A segment of the world’s population—perhaps 40% or more—may have partial protection thanks to “memory” T cells, the part of our immune system trained to recognize specific invaders. This could originate from cross protection derived from standard childhood vaccinations. Or, as one paper suggested, it could trace back to previous encounters with other coronaviruses, such as those that cause the common cold. This might mean that we are closer to herd immunity that we formerly thought. Herd immunity is a condition in which enough of the population develops a mild version of the virus that they block further spread and the pandemic ends.

I publish this post because as gloomy as things look today, there is light at the end of the coronavirus tunnel. Take heart!


  • Jayne August 15, 2020 at 1:28 pm Reply

    I’m in Laboratory work and I don’t have much faith in the 20 min quick tests. Have also heard examples of not identifying Positive COVID and one lady who felt sick waited in line for 2 hours and went home without being collected. She received a letter telling
    Her she tested positive. Never got to the front of the line to have a sample collected.

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