COVID-19 spreads when an infected person breathes out droplets and very small particles that contain the virus. These droplets and particles can be breathed in by other people or land on their eyes, noses, or mouth. In some circumstances, they may contaminate surfaces they touch. People who are closer than 6 feet from the infected person are most likely to get infected.
Key Points Available evidence suggests the currently authorized mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna) provide protection against a variety of strains, including B.1.1.7 (originally identified in the United Kingdom) and B.1.351 (originally identified in South Africa). Other vaccines show reduced efficacy against B.1.351 but may still protect against severe disease. Continued monitoring of vaccine effectiveness against variants is needed. A growing body of evidence indicates that people fully vaccinated with an mRNA vaccine (Pfizer-BioNTech and Moderna) are less likely to have asymptomatic infection or to transmit SARS-CoV-2 to others. Studies are underway to learn more about the benefits of Johnson & Johnson/Janssen vaccine. However, the risk for SARS-CoV-2 infection in fully vaccinated people cannot be completely eliminated as long as there is continued community transmission of the virus. At this time, there are limited data on vaccine effectiveness in people who