Will we still need to wear masks and practice physical distancing once a vaccine is available?
We will still need to wear masks and practice physical distancing until a large proportion of the population is vaccinated and we are sure the vaccine provides long-term protection. Initially, we will not have enough vaccine to vaccinate everyone who wants the vaccine and the virus will still be transmitted.
Although the phase 3 clinical trials are designed to determine whether vaccinated individuals are protected against disease, it will also be important to understand whether vaccinated individuals are less likely to transmit the virus. This is likely but not ensured. If a vaccine not only protects against disease but reduces transmission, and continues to do so for many years, we are likely to reach a state of herd protection when masks and physical distancing will no longer be required. Herd protection is achieved when a sufficient proportion of the population is made non-infectious through vaccination or natural infection so that the likelihood of an infectious individual transmitting to a susceptible individual is very low.