Choosing Your Booster

Booster shots of COVID-19 vaccine are recommended for a huge number of people. The list includes everyone aged 65 and older, people who are 18 and older and who have medical conditions that put them at greater risk for a serious case of COVID, people who are 18 and older and more likely to be exposed to COVID at work, and everyone who received the Johnson & Johnson vaccine. In addition, you need to have received the initial doses of Pfizer or Moderna at least 6 months ago or the Johnson & Johnson vaccine at least 2 months ago.

Initially, the important regulatory and advisory organizations indicated that everyone should get the same vaccine as they had received in the past. Recently, they have indicated that people can choose which vaccine to get. Being able to choose raises many questions. Here are the important considerations: 

All of the vaccines are effective. All three available vaccines—Pfizer, Moderna, and Johnson & Johnson—work beautifully to reduce your chances of acquiring infection, spreading infection, having symptoms or severe disease, requiring hospitalization, and dying. Very small differences exist between them. That’s right. They decrease the likelihood that you will get infection and spread it to others. It’s that an amazing attribute of vaccines?

All of the vaccines have a similar side-effect profile. Like with any vaccine, a small percentage of people experience side effects, which are good signs that your body is building protection. For each of the vaccines, side effects could include tiredness, headache, or chills. While they may affect your ability to do daily activities, they should go away within a few days.

Dosages vary slightly. The dose of Pfizer and Johnson & Johnson are exactly the same as the original doses for those two vaccines. It’s the same medicine in the same dose. The Moderna booster is given at a half dose, compared with the original doses of Moderna.

Risks of complications for all of the vaccines is very, very low. So far, among the many millions of people who have received COVID vaccines, three complications, apart from the very rare allergic reaction, have cropped up in exceptionally rare cases.

• Of the 6.8 million Johnson & Johnson vaccine doses, fewer than 30 people, mostly women ages 18 - 49, had a rare blood clot disorder that may have been related to the vaccine.
• Men ages 50 – 64 are at slightly increased risk of Guillain-Barre Syndrome after having received the Johnson & Johnson vaccine. While it is a serious condition that often requires hospitalization, it is rarely fatal.
• Among the millions of Pfizer doses administered a handful men under the age of 30 had a mild and treatable inflammation of the heart muscle or the outer lining of the heart after receiving the vaccine. COVID-19 itself has a much higher likelihood of causing this complication than the vaccine does. While these complications are very rare, they may be a consideration as you decide which vaccine to get.

On whether to mix vaccine types. We know that receiving the same vaccine is effective and safe.  Studies, including this one, have shown that mixing vaccine types provides a similar or higher immune response in blood serum. While we are waiting for results about how this translates into real life, don’t wait to get a booster. We know enough now to say that all of the booster combinations are safe and effective. While the Centers for Disease Control and Prevention (CDC) still recommends sticking with the same vaccine as you received initially, they did authorize mixing.

If you ask a medical expert which booster to choose, they will likely say, “Take your pick. You can’t go wrong.” All of the vaccines provide extraordinary protection against acquiring infection, spreading infection, having symptoms or severe disease, hospitalization, and dying. And they do it with nearly non-existent risk of side effects or complications.

Marie George, MD, FIDSA, is the infectious disease specialist at Southwestern Vermont Medical Center in Bennington.