The crucial vaccine benefit we’re not talking about enough

COVID vaccines have proved to be magnificent successes, dramatically decreasing the number of cases, hospitalizations and deaths. However, there has been uncertainty about whether vaccinated people who still get infected—perhaps with very mild symptoms, or none at all—might pass on the virus to others. Such silent spread could complicate efforts to control the pandemic. In recent months, there has been a deluge of data on the risk of transmission after vaccination. These findings have important implications for how quickly we can get the pandemic under control, and for what we say to those who are hesitant about getting vaccinated. Vaccine trials are typically designed to determine whether an immunization prevents people from getting sick. These are the efficacy numbers in the headlines—as high as a 95 percent reduction in symptomatic COVID cases for the two FDA-authorized mRNA-based vaccines. But the trials provide little or no data on whether the vaccines can entirely...