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Pfizer COVID-19 Third Dose vs. Booster shot

There has been some confusion and misinformation on the COVID-19 vaccine “third dose” also sometimes referred to as the “booster” shot. Many are asking “what’s the difference?” Great question.

The third dose of the vaccine, which is available now, is for the immunocompromised individuals who may not have benefited from the full efficacy of the two-shot vaccine series because of their compromised immune system. The third, additional dose is needed to increase vaccine efficacy, essentially “catch-up” to the full protection the vaccine can provide.

A booster dose will soon be offered to individuals who were fully vaccinated, are not immunocompromised, and are eight months past their second dose, to provide a “boost” to increase vaccine efficacy, as the vaccine has been shown to decline in efficacy after a period of time. Per the CDC, the booster dose will be available starting with healthcare workers and follow a similar phased rollout as the COVID vaccine, on or around September 20, 2021.

Both the third dose and the booster dose are administered in the same way and in the same dosage as the first and second doses.

Also, as a reminder, we are only administering the Pfizer COVID-19 vaccine in our clinic for first, second and third doses. For details, please visit