FDA has started gathering more data on T-cell levels in people who have been vaccinated against COVID-19, which FDA biologics center Director Peter Marks says will help the agency better assess the efficacy of current and future coronavirus shots. Scientists and public health experts have urged FDA to look at the number of T cells, rather than just antibodies, produced by COVID-19 vaccines, saying it will help strengthen the United States’ coronavirus response and ensure companies produce better vaccines. Some...