Frequently Asked Questions about "Booster" Doses and Updated Vaccines

What is a “booster”?: “Boosters” are additional vaccine doses that you get after receiving a primary vaccine dose to increase immune protection against that specific illness. The term vaccine “booster” has been used broadly in public health across many vaccines. 

What is the difference between a vaccine “booster” and an updated vaccine? “Boosters” typically have the same formula as their primary vaccine dose, and they remind the immune system of what virus or bacteria to protect you against. Updated vaccines, like the annual flu vaccine, have formula changes compared to the original vaccine dose that increase its effectiveness against new circulating strains. 

As research improves our understanding of COVID-19, health agencies are now recommending updated vaccines instead of boosters. People who got the original COVID-19 vaccine series needed a “booster” when the original strains were still dominant. Now that new substrains have become dominant, updated vaccines are needed to specifically target the new dominant strains and maintain protection from COVID-19. 

Who can get “boosters”?: COVID-19 “boosters” are not available now that updated COVID-19 vaccines have been modified to target dominant virus strains. People who were previously eligible for a booster may now be eligible for an updated vaccine.

Who can get updated COVID-19 vaccines? Everyone should complete their age-appropriate, updated vaccine series. Updated Pfizer-BioNTech and Moderna vaccines are available for individuals as young as six months old. Updated Novavax vaccines are available for individuals age 12 and older. For the best protection this respiratory virus season, everyone should receive at least one dose of the updated vaccine. 

It is safe to get any of the authorized and updated vaccines, regardless of whether your primary series or most recent dose was the Pfizer-BioNTech, Moderna, Novavax, or Janssen/Johnson & Johnson vaccine. However, for children age six months to four years old, the CDC recommends receiving the same brand as the entire primary series, if available. 

When will updated vaccines be available? Updated COVID-19 vaccines should be available in your community by the end of December. The CDC recommends that everyone stay up-to-date on vaccinations by getting an updated vaccine dose at least two months after their last COVID-19 vaccination—either since their last dose, or since completing their primary series. 

Updated December 14, 2023 

Yes, everyone age six months and older should get an updated COVID-19 vaccine at least two months after their last dose. This is also true for people who completed their primary series or received one or two “boosters”. 

If you are recovering from a COVID-19 infection, you should consider delaying vaccination by three months from the start of your symptoms or positive test if you did not have symptoms. For specific guidance based on your health history, speak with your healthcare provider.

Updated December 14, 2023 

No, “boosters” were only given to fully vaccinated people. “Boosters” are no longer available and have been replaced with updated vaccines that target dominant virus strains.

The best way to protect yourself from getting severely ill from COVID-19 is to get vaccinated. The CDC recommends that unvaccinated people age six months and older get the updated primary series, and then wait at least two months to get their second or third updated Pfizer-BioNTech or Moderna vaccine dose. 

Adults age 18 and older also have the option to receive an updated Novavax vaccine instead of an updated Pfizer-BioNTech or Moderna vaccine if they are unable to receive mRNA vaccines and haven’t previously received any other updated dose.

Updated December 14, 2023 

No, all COVID-19 vaccines have been effective at reducing the risk of severe illness. Getting a series of vaccine doses over an extended period of time – like months or years – is common for many vaccines. Healthcare providers recommend these vaccine series because over time the vaccine dose effect wanes and another dose is needed to restore optimal protection against new variants of a virus. The researchers who developed the COVID-19 vaccines continue to watch for waning immunity, how well the vaccines protect against new strains of the virus, and how that data differ across age groups and risk factors. This research has led to updated vaccines.

In the past, “boosters” have extended COVID-19 vaccine protection against serious illness, but they have been somewhat less effective in boosting immunity against new variants. The updated vaccine formula is designed to better target and protect against variants that currently account for most new infections.

Updated December 14, 2023 

Messaging Resources about "Booster" Doses and Updated Vaccines

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