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Pfizer COVID booster FAQ: New variant, vaccine side effects, who's eligible and more

The new COVID-19 omicron variant is raising concerns. Here's what to know so far about Pfizer's booster vaccine, the mutated virus and what the CDC now recommends.


Adults who received Pfizer's COVID-19 vaccine can get a booster after six months.

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For the most up-to-date news and information about the coronavirus pandemic, visit the WHO and CDC websites.

In response to the new COVID-19 variant called omicron, the Centers for Disease Control and Prevention simplified its booster recommendation. Now, everyone ages 18 and older should get a booster shot, whether 6 months after their initial Pfizer or Moderna series or 2 months after their initial J&J vaccine

The CDC recommendation tweak comes as scientists rush to understand the new COVID variant and countries restrict travel to guard against another wave of the disease. Pfizer said it is investigating the new strain and will create a modified version of its vaccine if needed.

The omicron variant has a high number of mutations that scientists fear could help the new strain spread more quickly than the delta variant, which took hold in the US over the summer. The vaccines that are approved by the US Food and Drug Administration have proved to be highly effective in preventing severe illness. People who remain unvaccinated account for nearly all hospitalizations and deaths.

Multiple studies show that the effectiveness of vaccines may start to decline after six to eight months. Recent studies say a booster dose of Pfizer shows 95.6% efficacy against COVID-19.

We'll tell you the current details of the new omicron variant and Pfizer's vaccine, as well as who's eligible for the booster shot today. For more on COVID-19, here's what we know about COVID-19 vaccines for kids, and here's the latest guidance on masks and on breakthrough infections. Here's what you should know about the new federal COVID-19 vaccination mandates -- and what to do if you lost your vaccine card.

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What are Pfizer's plans for the omicron COVID-19 variant?

Pfizer said it is investigating the new mutated COVID-19 strain and is working to have more information about how effective its vaccine is against the omicron variant within two weeks, Reuters reported. If the drug-maker needs to create a tailored version of its vaccine to guard against the omicron variant, it could have the updated vaccine available in approximately 100 days, it said.

Moderna said it's now working on a vaccine candidate modified for the new variant.

Who's does the CDC say is eligible for a Pfizer COVID-19 vaccine booster?

The new answer: All adults 18 years of age and older should get a booster shot six months after receiving their second Pfizer or Moderna vaccine shot or two months after the Johnson & Johnson vaccine shot.

Pfizer is also seeking approval with the FDA for a booster shot for 16 and 17 year olds.

Does the Pfizer booster shot have side effects?

The CDC said those who received the Pfizer booster reported fewer side effects than after getting the second dose of Pfizer's vaccine, with headache, fever, fatigue, pain and chills the most frequently reported mild side effects.

The CDC said as of Nov. 14, 99% of those who received the Pfizer vaccine for the first two shots chose to receive a Pfizer booster, with the rest picking a Moderna or Johnson & Johnson booster. Here's more on mixing and matching vaccines.

Where can I get a booster shot?

According to White House Coronavirus Response Coordinator Jeff Zients, boosters will be available at roughly 80,000 places across the country, including over 40,000 local pharmacies. Some 90% of Americans have a vaccine site within 5 miles of where they live, Zients said, and getting a booster shot will be just as easy as getting the first shot. And the booster shot will be free too. 

You can check to see which vaccines are available where or call 1-800-232-0233 for vaccine information.

Why did Pfizer request authorization for booster shots for everyone 18 years of age and older?

If you're fully vaccinated, the CDC had said you would continue to be protected from infection and especially against serious illness. All the COVID-19 vaccine shots authorized by the FDA continue to be "highly effective in reducing risk of severe disease, hospitalization and death," according to the CDC.

Recent studies, however, show the effectiveness of the Pfizer vaccine can begin to wane after five or six months and a booster can raise your protection against infection, especially against serious illness. Albert Bourla, the chief executive of Pfizer, told the New York Times he anticipates the effectiveness of a booster to last a year, with annual booster shots possible to prop up immunity.

According to a recent study in The Lancet, those who received the Pfizer booster shot had a 93% lower risk of being hospitalized, a 92% lower risk of severe disease and an 81% lower risk of death, compared with those who had received their second shot at least 5 months before.

What about mixing and matching the COVID-19 booster shot?

The CDC said those who qualify for a booster shot can get any of the three available -- a booster from Pfizer, Moderna or Johnson & Johnson -- no matter which one they received first.

When can I get the Pfizer booster shot?

Now, if you're eligible. At least 31 million people have already received a booster shot, the CDC reported on Friday.

State and local health officials have started to roll out campaigns to help the public better understand who qualifies immediately, according to the New York Times

Is the Pfizer booster the same as the first two shots?

Yes. According to Pfizer, its COVID-19 booster would be a third jab of the same vaccine you got with the first two doses. 

Pfizer is working separately with its partner BioNTech on a version of the COVID-19 vaccine that targets the delta variant.

For more on coronavirus treatments and vaccines, here's what we know about monoclonal antibody treatments, the new federal vaccine mandates and why some people may not want the shot.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.