Blood Donations Show That the United States is Still Nowhere Near COVID Herd Immunity

USA

499302214874423a54f42CPhoto: Cory Doctorow/FlickrCC

To better understand how widely the coronavirus has spread in the United States, some researchers are turning to an unusual source of data: blood donations.

In an effort to encourage more donations, many blood collection centers have been offering to test donated blood for antibodies to the coronavirus, which indicates a past infection with SARS-CoV-2, the virus that causes COVID-19. Of the nearly 1 million Americans who donated blood to the Red Cross from June 15 to August 23 and were tested, only 1.82%  had the antibodies. That finding suggests that the vast majority of Americans have yet to be infected with the virus, researchers report September 14 in JAMA.

Blood donations aren’t a random sample of the population, but the data can give researchers an idea how much of a population has been exposed to the virus, a concept known as seroprevalence, and how susceptible different populations remain to continuing outbreaks.

While seroprevalence was generally low across the country, there was variation among different demographic groups. African-American and Hispanic donors had slightly higher seroprevalence, compared with white donors, which matches patterns seen in clinical diagnoses of COVID-19.

Seroprevalence varied by region too. All regions except the Northeast experienced modest increases in seroprevalence over the course of the summer. By August 23, the South had a seroprevalence of about 2.9%, higher than the Midwest (about 2.7%) or West (about 2.4%) or Northeast (about 2.1%).

Originally published by Science News. Republished here with permission.