A: There isn’t enough information yet about how long a vaccine’s protection against COVID-19 will last. Many vaccines, such those for the flu, need to be periodically readministered. Over time, scientists will learn more about long-term protection. People might need multiple doses of a COVID-19 vaccine for broader protection.

All of the COVID-19 vaccines were shown to be very highly effective (90% or higher) at preventing COVID-19 in clinical trials and in real world conditions. However, some people who are fully vaccinated against COVID-19 may still get sick because no vaccine is 100% effective.  These breakthrough infections are rare and appear to result in less severe illness and less hospitalization. CDC is continuing with studies to understand how often this occurs, how severe the illness, and how likely a vaccinated person is to spread COVID-19 to others.

Visit the CDC website for more information.