A booster is an additional dose of vaccine that can help prolong protective immunity in someone who responded fully at first, but there's evidence that protection is declining after some time. "In essence, it's a 'top-up' of a person's antibody-mediated immune response to the first vaccine series," says Dr. Sostman. "Circulating antibodies are the first line of defense against getting infected or becoming ill if you are infected." Boosters are being recommended because data is showing that protection against mild and moderate COVID-19 via the initial vaccine series declines over time — particularly for those who were vaccinated some time ago. Added to that is the concern about the new COVID-19 variant, omicron.
So start the new year with a boost!