The Red Cross is experiencing a shortage of blood donations during the pandemic as blood drives have been canceled. (Photo by Sarah Reingewirtz, Los Angeles Daily News/SCNG) The COVID-19 antibody positivity rate over time is as follows:AdvertisementThe Red Cross said those numbers are from the first week of each respective month and should not be considered cumulative.As of March 24, the United States had recorded more than 29.9 million COVID-19 cases, according to data collected by Johns Hopkins University.
That total is a result of testing through nasal swabbing.The results from antibody tests, which require drawing blood, aren’t included in the case total.