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When to Get Your Booster Shot, Says Doctor

Everything you need to know about the Pfizer, Moderna, and Johnson & Johnson booster shots.

You are fully vaccinated with your initial round of shots. However, it may be time for a booster. There is a little confusion surrounding who needs a booster and when, especially since every vaccine is different. Darren P. Mareiniss, MD, FACEP, Assistant Professor of Emergency Medicine, Sidney Kimmel Medical College – Thomas Jefferson University in Philadelphia, PA, is here to clear up the confusion. Read on to find out more—and to ensure your health and the health of others, don't miss these Sure Signs You May Have Already Had COVID.


If You Got the Pfizer Vaccine

Glass bottle with logo Pfizer and BioNTech in the doctor's hand.

Those aged 65 and over or 18 and over with comorbidities that put the patient at risk for severe disease, in addition to those who have high exposure professions (e.g., doctors/nurses in the ED) can currently get a Pfizer booster. "The booster should be six months after the second shot," Dr. Mareiniss confirms. Here is a simple summary:

COVID-19 Vaccine booster shots are available for the following Pfizer-BioNTech vaccine recipients who completed their initial series at least 6 months ago and are:

You can also mix and match brands. Next, learn about Moderna.


If You Got the Moderna Vaccine


For those who got Moderna, "The FDA advisory committee unanimously approved the same booster recommendations as the above Pfizer recommendation for people above 65 and with comorbid conditions at 6 months post second vaccine administration," Dr. Mareiniss adds. The CDC vaccine advisory committee and the CDC director agreed yesterday, and shots could be available as soon as this weekend. You can get a booster of any brand, if you prefer.

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If You Got the Johnson & Johnson Vaccine

Syringe Injection placed against Johnson and Johnson logo

The FDA and CDC approved boosters for all recipients of J&J regardless of comorbid condition, for everyone 18 and older. "All recipients of J&J should receive another dose two months after the initial dose," says Dr. Mareiniss. Also, the FDA and CDC have approved substituting Moderna or Pfizer as a second dose if desired or necessary. "Notably, a study showed an increase in antibody production when either Moderna or Pfizer was used as a second dose," he adds.   


If You Are Immunocompromised

woman in bed suffering from cancer

If you are immunocompromised, you will need a booster sooner rather than later. "Essentially, all immunocompromised people need a third mRNA shot (Moderna or Pfizer)," explains Dr. Mareiniss. "All J&J recipients have been approved for and need a second shot at two months after the first shot." He added: "You should think of these shots as necessary to complete a protective course." The coronavirus vaccines "are all highly effective in reducing the risk of severe disease, hospitalization, and death, even in the midst of the widely circulating Delta variant," Dr. Rochelle P. Walensky, director of the C.D.C., said in a statement. 


What Side Effects Should You Expect?


Symptoms after receiving a booster have been similar to those experienced after the second shot, maintains Dr. Mareiniss. "Patients may experience pain at the injection site, headache, fatigue, myalgia and/or a brief period of fever."  

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What Will Happen If You Don't Get a Booster

The vaccines are still very effective for preventing hospitalization and death if you do not get a booster. "However, we have seen waning antibody immunity and more likely symptomatic infection over time," Dr. Mareiniss says. "If you do not get a booster, you will be more susceptible to symptomatic infection."  


Will You Need Another Booster Later On?

Doctor holding a syringe

Many people are wondering if they will need another booster. "This is unclear at this point and will depend on several factors," Dr. Mareiniss explains. "We will need to see if there is any further waning immunity or a new variant that may require boosters. Currently, this remains to be seen." 

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You Had COVID and Have Been Vaccinated. Do You Still Need the Booster? 

Woman in medical protective mask getting injection in arm vaccination.

If you had Covid after your initial series of vaccination, you should still get a booster if you are one of the eligible groups, suggests Dr. Mareiniss. "This is particularly important for recipients of the J&J vaccine as a booster is recommended for this entire population in order to ensure adequate protection against the delta variant," he says. And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Leah Groth
Leah Groth has decades of experience covering all things health, wellness and fitness related. Read more about Leah