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What are the possible side effects of the new omicron booster? Experts explain

New COVID-19 boosters mean better protection, but also some side effects.

For the first time, updated COVID-19 boosters targeting specific omicron strains of the coronavirus are available. These boosters may better protect against COVID-19 infections with the variants currently circulating — specifically BA.4 and BA.5.

But, as with all the previous coronavirus vaccines, the new omicron-specific COVID-19 boosters may come with some side effects. For most people, those side effects will likely be mild. But they can still interfere with your life. Symptoms like arm soreness or general fatigue can make it challenging to go through the motions of work and school.

So, before you get your next shot, here's what you need to know about the side effects you might experience and experts' advice to make them bearable while your body builds up that crucial immune response.

Who is eligible for an omicron-specific booster?

Anyone who is at least 12 years old and received a primary series of COVID-19 vaccines may be eligible to get the updated boosters, the Centers for Disease Control and Prevention say.

But it must have been at least 2 months since your last vaccine dose, the CDC explains. At that point, those who are between the ages of 12 and 17 can receive the updated Pfizer/BioNTech COVID-19 booster. And those who are 18 and older can get either the Moderna or Pfizer/BioNTech updated shots, the CDC says.

If you've had a COVID-19 infection recently, you can also consider waiting up to three months to get your new booster, according to the CDC. But, depending on your individual risk factors for severe disease and the level of coronavirus transmission in your area, you may want to go ahead and get it sooner anyway.

What side effects are possible with the updated booster?

The Food and Drug Administration and CDC advisory panels reviewed available data about the updated boosters when making their decisions to authorize and recommend them. But the companies' human clinical trials with these specific formulations are still in progress.

So, the expert groups reviewed the data the companies have so far about the new shots as well as data looking at previous versions of the shots, which targeted the BA.1 variant and the original strain.

Overall, though, experts said they expect the side effects with these boosters to be generally the same as those seen with the previous shots. For instance, in both the Moderna and Pfizer trials, the most common side effects were pain at the injection site, fatigue and headache. Participants also reported muscle and joint aches, fever, chills, nausea, vomiting, swollen lymph nodes, and redness and pain at the injection site.

"There's no reason at all to expect that this would be different or somehow give you some bad new side effects that we don't know about," Dr. Otto Yang, professor of medicine in the division of infectious diseases and of microbiology, immunology and molecular genetics at the David Geffen School of Medicine at UCLA, told TODAY.

"You can expect (the updated booster will) be very similar to your prior shots," he said. "So if you had a lot of side effects from your prior vaccinations, I think you can expect it'll be similar." And if you had a relatively mild time previously, there's a good chance you'll have the same experience with this version.

“The side effects that most people get with the COVID shots are usually just local reactions,” Dr. Frank Esper, a pediatric infectious disease specialist at the Cleveland Clinic, told TODAY. “They get a little pain in the arm, they get a little swelling.”

Dr. Thomas Murray agreed: "Far and away I think the most common side effect that people will see will be pain at the injection site," Murray, associate professor of pediatric infectious diseases at the Yale School of Medicine, told TODAY.

Some people might also experience systemic reactions, like fatigue or a low-grade fever, the experts said.

The expected side effects:

Based on information from clinical trials, the CDC and experts TODAY spoke with, these are the most common side effects to expect with the updated omicron boosters.

  • Injection site reactions (pain, redness and swelling)
  • Fever
  • Chills
  • Fatigue
  • Headache
  • Nausea
  • Muscle aches

How to safely manage omicron-specific COVID-19 booster side effects

The most important thing to do is schedule your booster shot strategically. "If you're that person who does feel rundown the next day, plan ahead," Esper advised. Try to time your shot for a day in which you don't have much going on so that, if you do have to take it easy, you won't be missing much.

After you've gotten your booster, there are other ways to manage your symptoms:

  • For aches, pain and fever, take over-the-counter medication such as acetaminophen or ibuprofen. Wait at least 4 hours if you can, Yang advised, but don't hesitate to take the medication if you're really in pain.
  • To help alleviate arm soreness, the CDC suggests stretching, exercising and gently using the arm.
  • A compress might also help ease injection site reactions. The CDC recommends using a clean, cool, damp towel. And Esper says some people might find a warm compress helps, too.

One thing to note, per Murray: If your symptoms don't resolve within 24 to 48 hours, you should reach out to your health care provider just to make sure nothing else is going on.

"I know many people who had the vaccine and, unfortunately, were incubating COVID at the same time," he explained. So, when their fever didn't resolve after a few days, they took a COVID-19 test — and found out they were positive.

If getting a new booster seems like a hassle, remember that the alternative may be much less pleasant. "Nobody likes a shot, but certainly no one likes to be laid up for a week with bad COVID," Esper said. "That's a heck of a lot more disruptive to your life than just the sore arm — and it has the potential to be even worse if you get really sick."