A booster dose is intended to offer a boost of immunity after original vaccination. This is recommended for everyone 18 and older because there is evidence that the effectiveness of the vaccine wanes over time.
A third dose is recommended for people who are immunocompromised and who received the Pfizer or Moderna vaccine series. This is recommended because there is evidence that this group doesn’t build up the same level of immunity after two doses of mRNA vaccine.
The CDC recommends everyone 18 and older gets a booster shot.
Teens 16–17 years old may get a Pfizer COVID-19 vaccine booster.
Although the COVID-19 vaccines remain effective at reducing risk of severe disease, hospitalization and death, the CDC has found that their protection against mild to moderate disease decreases over time. Studies have shown that a booster shot not only lengthens immunity but helps to broaden and strengthen your immune response, even against variants such as omicron.