A booster is an extra dose of a vaccine that makes its protection last longer. Boosters are not new. They are common for many vaccines. The COVID-19 vaccines provide very strong protection, but like other vaccines, it can decline over time, especially if you are older or have a weakened immune system. Boosters help protect you longer.

COVID-19 vaccines are effective: Research has shown that COVID-19 vaccines remain very effective in protecting against severe diseases. With booster shots, this protection can last longer. A COVID-19 booster shot is an additional dose of the vaccine given after the protection provided by the initial shot(s) has started to decrease over time.

Boosters are not new: Examples of other vaccines needing booster shots are Pneumococcal, tetanus, Haemophilus influenzae type b (Hib), Polio, and chickenpox. COVID-19 booster shots are exactly the same dosage and composition as the initial doses.

COVID-19 booster shots are needed because  

• Many vaccines’ protection declines over time, especially for older people and those with weakened immune systems. 

• New COVID-19 variants of concern (such as Delta and Omicron) may require an extra layer of protection.