Two preliminary retrospective studies in the United Kingdom, sub-Sahara Africa, and the United States suggest that some people who were never infected with the virus that causes COVID-19 have cross-reactive antibodies against it—perhaps from previous exposure to similar human coronaviruses.SARS-CoV-2 and the common coldThe first study, published late last week in Science, was the result of an accidental discovery by researchers at Francis Crick Institute and University College London while testing the performance of sensitive COVID-19 antibody tests by comparing the blood of COVID-19–infected donors with that of those who had not had the disease.They found that blood samples from some noninfected donors—particularly children—contained