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Do you need a COVID-19 booster shot?

These 4 groups are now eligible—if you had the Pfizer vaccine. Here’s what you should know.

CORONAVIRUS UPDATE: As experts learn more about the novel coronavirus, news and information changes. For the latest on the COVID-19 pandemic, please visit the Centers for Disease Control and Prevention.

You have already gotten your COVID-19 vaccinations. Now, you may be hearing about booster shots and are wondering if you need one the more you hear about the Delta variant

Booster shots are nothing new. Other vaccinations, such as tetanus, require boosters because your immunity against these illnesses can start to decline with time—putting you at an increased risk of actually catching that illness. 

When it comes to coronavirus vaccinations, the Centers for Disease Control and Prevention (CDC) continues to monitor the effectiveness of these vaccines in protecting against COVID. Here are some of the most important things to know about the COVID-19 vaccine booster and how you can determine if you can benefit from a vaccine booster shot. 

Are COVID booster shots available?

On Aug. 25, 2021, the Pfizer-BioNTech COVID-19 vaccine booster was approved by the Food and Drug Administration (FDA) for adults aged 65 and older and adults at high risk of severe illness from COVID-19. The booster shot is the same as the two doses of vaccine that were given initially. However, information on the need for an additional dose after getting either the Johnson & Johnson or Moderna vaccine is still pending. 

Johnson & Johnson has submitted supporting data and asked federal regulators to authorize its own vaccine booster. The Johnson & Johnson single-dose vaccine is 71% effective against COVID-19, compared to Pfizer’s 88% and Moderna’s 93% effectiveness.  

Who is eligible for a COVID booster shot?

Only certain people who have gotten both doses of the Pfizer vaccine are recommended to get the third dose at this time. 

Not everyone needs or will need a booster, though as with many things in the COVID-19 pandemic, recommendations from health officials may change as research progresses. “Those with normal functioning immune systems likely have an adequate response from their two-dose series and do not require a booster at this time,” says Sanjeev Jain, MD, a board-certified allergist and immunologist at Columbia Allergy.

However, certain people, especially those who have weakened immune systems are more likely to have a decline in their body’s ability to fight off the virus over time. This group includes:

  • Older adults aged 65 and older and adults 50 to 64 years old with underlying medical conditions
  • Adults 18 to 49 years old with underlying medical conditions ages 
  • Adults 18 years and older living in long-term care facilities
  • Those with high risk of virus exposure, including healthcare workers, other frontline employees, and people in at-risk occupational and institutional settings

The FDA states if you meet this criteria, you might benefit from a booster dose and can get the shot six months after your second dose. “This is when a declined immune response is likely to start occurring based on current data,” explains Dr. Jain. “At this time, we recommend frequently checking the CDC’s website to stay up-to-date on booster guidelines.” When immunity declines, you may be more likely to develop severe illness from COVID-19.

SingleCare recently ran a survey about flu and COVID-19 vaccinations. Of the 1,000 respondents, 51% said they were fully vaccinated and plan to get a booster shot.

Why do we need a booster shot for COVID?

As of Oct. 4, 2021, over 185 million Americans have been fully vaccinated against COVID-19. Of those fully vaccinated, around 7 million people have received a third shot. 

“Like all vaccines, the efficacy of the COVID vaccine lessens over time, and research is still underway to understand what the decrease looks like for COVID specifically,” explains Beth Beatriz, Ph.D., epidemiologist and public health expert at This vaccine isn’t the same as a light switch, where one day it works, and the next it doesn’t. 

How long the COVID-19 vaccine works depends on several factors, including how much of the virus you’re exposed to, and your own immune response. That said, around six months after vaccination, there appears to be a significant decline in the COVID vaccine’s effectiveness, from about 92% to 75%, according to the CDC.  

“Pfizer drew the conclusion that the breakthrough cases of COVID in those that were vaccinated early in the process could be attributed to a weakened immune system response to the virus over time,” Dr. Jain says. To continue getting the protection the vaccine provides, a booster is now recommended.

“I want to emphasize here that even at 75% effectiveness the COVID vaccines are still highly effective in reducing serious illness and death,” says Beatriz. Recent studies from Moderna have been able to look at those who were vaccinated more than a year ago versus within the past eight months. If you were recently vaccinated in the past eight months, you may be less likely to get COVID than those who were vaccinated prior. 

Dr. Jain agrees: “Pfizer, Johnson & Johnson, and Moderna are all tracking data in regards to the longevity of the immune response and antibodies produced from these vaccines.” Researchers are continuing to monitor vaccinated individuals for a decrease in COVID antibodies to determine if a booster is needed. 

This is especially true when it comes to the appearance of new variants. At a minimum, Dr. Jain says, a booster should give you good immunity against the virus for at least six months, as the original vaccines did.  

What are the common side effects of the Pfizer COVID-19 booster shots?

For the most part, you can expect similar side effects to the booster that you might have experienced from your first vaccine doses. These can include:

“The main difference in side effects between the original vaccine and the booster was that more participants noted lymph node swelling in the underarm on the side the vaccine was administered with the booster than with the original two doses,” Dr. Jain explains. 

This can be a normal response of your immune system and is generally not a concern. In fact, it can be a sign your body is mounting a defense against illness. Pfizer and Moderna vaccines have higher instances where people have reported this underarm swelling than with other vaccinations. It’s possibly due to the fact that these are mRNA vaccines, which are a relatively new type of vaccine that may be stimulating a higher immune response than other types of vaccines. 

Where to get your COVID booster shot

If you received Johnson & Johnson vaccine or Moderna vaccine, continue to watch for the latest information from the CDC on when you can get a booster shot. In the meantime, you are still considered to be fully vaccinated against COVID-19. 

Those who received a Pfizer vaccine series may be able to get a booster shot, but not everyone needs one at this time. As the CDC collects more data, more populations might be recommended to get a booster. As with the original vaccines, COVID-19 boosters are free of cost regardless of your insurance or immigration status, according to a White House press briefing.

Here are some things to keep in mind when getting your booster:

  • Make sure you bring your CDC-issued COVID-19 Vaccination Record card to your appointment.
  • It’s not advised to take over-the-counter (OTC) pain medications, such as Tylenol (acetaminophen), before your booster shot.
  • Generally, you can take OTC medications after your booster, but make sure you talk to your healthcare provider first.

RELATED: What to expect after the coronavirus vaccine

Check with your clinic to find out if they are offering booster shots. Many pharmacies and grocery stores are offering the booster as well. You can find a pharmacy near you on or visit to find a location.