The Most Common Side Effects Of The New Covid Booster Jabs

Here's what to expect when you get the new Pfizer or Moderna vaccines and how to ease symptoms.
Side effects are a perfectly normal (and expected) response to the latest COVID vaccine.
filadendron via Getty Images
Side effects are a perfectly normal (and expected) response to the latest COVID vaccine.

Moderna and Pfizer have both produced new bivalent vaccines that target the original strain of coronavirus and Omicron subvariants (including the highly contagious BA.4 and BA.5), which have been rapidly spreading throughout the world for the last few months.

Both these vaccine have been approved for use by the Joint Committee on Vaccination and Immunisation for the autumn booster rollout programme.

At this point, anyone aged 65 or over in England, frontline health and social care workers, the immuno-compromised and those with health risk factors, as well as their carers, plus all pregnant women, will have been invited for a booster.

In the coming weeks, more than 26 million people in England will be able to access the new vaccine.

As with the last booster jab and the original vaccines, certain side effects are to be expected (and show that the booster is working!).

Here’s what to know about the side effects of these new bivalent vaccines.

The side effects resemble those of the earlier Covid jabs

“The anticipated side effects are really exactly what would be expected to occur after the previous vaccinations,” says Dr. William Schaffner, a professor of preventive medicine in the department of health policy at Vanderbilt University Medical Center.

Those include headache, fatigue and soreness or redness at the injection site, Schaffner explained. The US Centers for Disease Control and Prevention also notes that a fever is a common side effect after booster jabs.

Chills, muscle pain and joint pain were also reported, according to the US Food and Drug Administration.

It’s important to remember that these side effects are actually a good thing.

Yvonne Maldonado, a paediatric infectious disease professor at Stanford University, previously told HuffPost that “most vaccines will have some degree of minor side effects. It is, in fact, the body’s immune and inflammatory response to the vaccine.”

This immune response can present itself as redness at the injection site, headache or fever, Maldonado said.

You can expect swollen lymph nodes, too — but don’t delay a mammogram because of it

Swollen lymph nodes, particularly in the armpit of the arm where you got the shot, can be expected, too, according to Medical News Today.

This is another side effect that was widely reported after previous Covid vaccinations and boosters. When the vaccine was first available, some people reported that this issue interfered with mammograms — swollen lymph nodes can resemble a sign of breast cancer on this kind of screening.

If you have a mammogram scheduled soon after your Covid booster, let your doctor know you were recently vaccinated so they’re aware of any potential issues with imaging.

If you experience these symptoms, you can take medicine to help relieve them

Schaffner noted that if you’re experiencing any of these unpleasant symptoms, you can take a pain reliever to combat them.

Over-the-counter anti-inflammatory drugs should make you feel better and allow you to go through your daily activities, he notes.

He adds that if your pain or discomfort gets bad enough, you should contact your doctor. But adverse reactions are very rare and occur in a few cases per million.

Plus, most severe reactions happen within 15 minutes of vaccination, which is why you’ll be asked to wait for 15 or 30 minutes after your booster so medical staff can monitor you.

If you experience discomfort after your omicron-targeting booster, you can take over-the-counter pain relievers.
bymuratdeniz via Getty Images
If you experience discomfort after your omicron-targeting booster, you can take over-the-counter pain relievers.

Plan to take it easy the following day

If you’re someone who has dealt with tiredness, fever or headache after getting vaccinated – or if you’re just feeling anxious about the potential side effects – plan to get your jab when you don’t have much going on the next day, Schaffner says.

In other words, if you’re nervous about side effects, you shouldn’t get the vaccine the day before a big event in case you end up feeling lousy.

All in all, it’s important to get the new Covid booster

The most recent COVID subvariants are more contagious than ever and are only expected to grow more transmissible as the virus continues to mutate.

Dr. Gregory Poland, a professor of medicine and infectious diseases at the Mayo Clinic, previously told HuffPost that the goal of a virus is to infect more and more people. So, it will mutate to become more and more contagious — which is what we’re seeing with the BA.4 and BA.5 subvariants.

The best way to protect yourself from omicron, which is the current dominant strain, and any future subvariants is by getting this updated bivalent booster.

Experts are still learning about Covid-19. The information in this story is what was known or available at the time of publication, but guidance could change as scientists discover more about the virus. To keep up to date with health advice and cases in your area, visit and

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