WEDNESDAY, March 17, 2021 (HealthDay News) -- COVID-19 antibodies were found in the blood of about one in five donations from unvaccinated donors in the first week of March, American Red Cross data show.
The organization tested more than 3.3 million donations from unvaccinated people in 44 states between mid-June 2020 and early March 2021. Across the entire period, about 7.5 percent of all of those donations had COVID-19 antibodies, CNN reported. But the percentage of donations with antibodies has risen steadily over time, the Red Cross noted. Rates of positive tests for COVID-19 antibodies in blood donations rose from about 1.5 percent in the first week of July to nearly 4 percent in the first week of October and then rose again to 12 percent by the first week of January and to nearly 21 percent by the first week of March.
"Blood donors are not a random sample of the general population, but they're interesting," said William Schaffner, M.D., a longtime adviser on vaccines to the U.S. Centers for Disease Control and Prevention. Schaffner added that two key points stand out. "The first is that a substantial portion of the U.S. population has experienced COVID, at least the blood donor population, knowingly or unknowingly. The other is that a huge proportion of the U.S. population has not -- it's the 80 percent," he said. "So we can't rely just on the strategy of letting herd immunity occur naturally. We've got to vaccinate in order to get up to 80 percent of the population to be immune."
There have been about 29.5 million reported cases of COVID-19 in the United States, according to data from Johns Hopkins University, representing about 9 percent of the population. But experts estimate the actual number of cases is much higher, which tracks with the Red Cross findings.