A huge percentage of Americans have already had COVID-19: Why studies of feces can help assess the spread

Last week, the director of the CDC, announced COVID-19 cases in U.S. may be 10 times higher than reported.

As of Tuesday morning, there were over 2.6 million confirmed cases in the U.S. The CDC’s assessment would put the number of Americans who have been infected with COVID-19 around 26 million people. That is close to 10 percent of the population.

The assessment is based on the presence of antibodies in blood samples from across the country. For every confirmed case of COVID-19, 10 more people had antibodies.

Why is this CDC finding significant? If 10 percent of Americans have had COVID-19, many of these infected people had such mild cases they didn’t seek treatment. Many likely never even knew they had it.

It also suggests the coronavirus is far less deadly than we’ve previously believed. The CDC study suggests the all-age death rate from the virus is roughly .5%, although many experts believe the death rate is even lower.

Still, knowing just how widespread this virus is will play a large role in taking actions aimed at protecting the population. That’s why cities and states across the U.S., and in England, are testing feces from wastewater.

People infected with the virus can shed it within 3 days of exposure, often much quicker than they develop symptoms. And people without symptoms never get tested at all. Studying wastewater, and looking for virus particles in the feces, can give us a more complete picture of how the virus is spreading.

Plus, scientists can analyze waste without subjecting millions of Americans to blood testing, possibly giving us a better way to tell truly how widespread COVID-19 is.