Scientists at the National Institutes of Health who studied blood samples from across the United States have discovered that for every coronavirus infection recorded during the spring and summer of 2020, nearly five more went undetected — amounting to nearly 17 million additional cases by July 2020. A team of immunologists, engineers, clinicians and statisticians across the NIH worked together to try and get a better handle on the number of undiagnosed coronavirus infections by looking for antibodies in blood samples. Volunteers used a lancet to prick their fingertip and squeeze out droplets of blood that they deposited into sampling devices. Does the recognition of all these previously overlooked cases mean the country is closer to reaching herd immunity than previously thought? It’s unknown how long the immunity gained from a coronavirus infection lasts, and whether this so-called natural immunity offers strong protection against an array of viral variants.
