Summary
Other than a placebo-controlled, clinical trial lasting many months and involving tens of thousands of people, is there any way to be sure a COVID-19 vaccine will work? Many researchers say the vaccines already in use offers a shortcut: Simply gauge a vaccine’s ability to elicit so-called neutralizing antibodies, which bind to the virus and prevent it from entering cells. But several recent studies point to other “correlates of protection”: “binding” antibodies—which latch onto the virus but don’t block entry—and another set of immune warriors called T cells. Vaccine decisions may soon depend on a better understanding of these supporting actors. Several manufacturers are developing updates of their COVID-19 vaccines tailored to protect against new viral variants that could be used as booster shots. The companies hope regulatory agencies won’t require evidence of efficacy in big clinical trials, which are time-consuming, expensive, and increasingly ethically fraught because someof the participants receive a placebo even though proven vaccines are now available.