Immunity

Yes. When someone who is fully vaccinated tests positive for COVID-19, it is called a “breakthrough” case. Breakthrough cases are expected and relatively common. Oftentimes, vaccinated people who have a breakthrough infection are asymptomatic or have mild symptoms.

However, even in asymptomatic or mild cases, it is possible for someone who is fully vaccinated to transmit COVID-19 to others. This is particularly true when someone is infected with the highly transmissible Delta variant.

Clinical studies show that the effectiveness of the Pfizer-BioNTech and Moderna vaccines wane about six months after the second shot. Therefore, the CDC now recommends that everyone 5 and older receive a booster dose. A second booster dose is also recommended for some people including people ages 50 and over and those 12 and older who are immunocompromised.

Learn more about the vaccine and booster shots in our COVID-19 vaccine info hub.

Yes, the CDC recommends that those who are eligible get a booster shot. This includes an updated (bivalent) booster for anyone 6 months and older. A second booster dose is also recommended for some people. Learn more about the vaccine and booster shots in our COVID-19 vaccine info hub.