Labs and blood banks collect millions of blood samples each month, offering a distinctive source of data on the disease…

Their data so far suggest that a lot of people have had Covid-19 without ever receiving a diagnosis. Confirmed case counts suggest that almost 7 percent of people in the U.S. have had the virus. Data from the arm of the study looking at blood from clinical laboratory tests from all 50 states, the District of Columbia, and Puerto Rico found rates of antibody positivity that at times ranged from under 1 percent in some states to 23 percent in New York…

Some experts have reservations about the use of blood donation data to estimate the prevalence of Covid-19. “The problem with blood donors — and this is also supported by evidence from other epidemics like HIV, and previous pandemics — is that blood donors are weird people” from a statistical point of view, said Gideon Meyerowitz-Katz, an epidemiologist at the University of Wollongong. “And blood donors who give blood during a pandemic, when the country is in lockdown in particular, are very weird people.”

What Scientists Are Learning About Covid-19 Using the Nation’s Blood Supply — Science | Smithsonian Magazine

A long but interesting article from Smithsonian Magazine.

“Blood donors are weird people”.