Red Cross: 5.5% of blood donations have COVID antibodies

About 5.5 percent of all the Red Cross blood donations from healthy, unvaccinated Connecticut residents since June have tested positive for COVID antibodies, the organization said this week.

Overall, the Red Cross tested 3 million blood donations, including 82,353 in Connecticut, between mid-June 2020 and mid-February.

The national positivity rate was 6.6 percent over that time, higher than Connecticut’s average, suggesting the spread of the coronavirus was better contained in this state than in others. In fact, the Northeast had a lower positivity rate than other U.S. regions.

In the Northeast, only 13.86 percent of donations tested positive during the week of Feb 13, the lowest of the nation’s four Census regions. That same week, 24.54 percent of blood donations in the Midwest tested positive.

The percent of Red Cross blood donations that tested positive for COVID antibodies increased considerably in recent months, going from 1.18 percent nationwide in June to 20.20 percent in February.

That growth in positivity mirrors the increase in hospitalization rates and test positivity seen in Connecticut and nationwide over the holidays.

The Red Cross is careful to warn that the data does not necessarily indicate immunity, though Centers for Disease Control and Prevention adviser William Schaffner told CNN that the Red Cross data demonstrates the ineffectiveness of a herd immunity strategy.

Though the data does show “that a substantial portion of the U.S. population has experienced COVID, at least the blood donor population, knowingly or unknowingly,” he said, it’s not nearly enough to stop transmission of the virus, even if every one of those blood donors is immune.

"So we can't rely just on the strategy of letting herd immunity occur naturally,” Schaffner said. “We've got to vaccinate in order to get up to 80 percent of the population to be immune.”