What Are the Side Effects of the Bivalent Booster? Here's What Doctors Want You to Expect

·4 min read

With the recent release of the bivalent booster and many people signing up to get it, many of us have questions regarding its effectiveness, how well it protects against infection and side effects of the shot.

Will the side effects be similar to the other COVID vaccines? Here’s what you can expect, according to doctors.

How the Bivalent Booster Works

This new booster targets the original COVID-19 strain as well as the newer omicron subvariants which are the dominant ones such as BA4/BA5.

The benefit of this is that you get immunity to the original SARS COV-2 virus as well as newer variants that can sometimes evade vaccine immunity and are more contagious, Purvi Parikh, MD, explains. This way you are very well protected hopefully from mild to moderate and severe forms of the infection and hopefully not get infected at all.

Related: There's a New Omicron-Specific Booster—Here's Everything You Need to Know About It

Kristen Nichols, PharmD, BCPS, BCPPS, BCIDP, says another way to think about this is by comparing it to the yearly flu vaccine that we get. Most flu vaccines today protect against four strains of the influenza virus, though some still protect against only three. The composition of that flu vaccine, in terms of which specific strains of the virus it targets, changes from year to year.

The new vaccine contains the same total amount of spike protein, but half of it looks like the spike protein on the original SARS-CoV-2 virus, and half of it looks like the spike protein on the BA.4/BA.5 Omicron variants (the spike protein on those two variants is identical).

Having a more specific spike protein for the immune system to look for should make the vaccine more effective at preventing infection and severe disease with the currently circulating variants. Also, since the immune system will now recognize two similar variations, it may be more efficient at also recognizing new variants.

You can think of it like the immune system is getting a picture of a guy to “be on the lookout” for. The original vaccine was what the guy looked like as a young man, but now, he’s grown and aged and looks a little different. So now we have a new vaccine, which is a little more specific to what the guy looks like today, Dr. Nichols adds.

The Side Effects of the Bivalent Booster

Dr. Parikh explains the side effects are similar to any vaccine (including the original COVID vaccine) which include:

  • Arm soreness at the injection site

  • Muscle aches

  • Fatigue

  • Fever

  • Headaches

These are expected, and side effects are short-term and not dangerous.

Side effects can also differ depending on age. Some reports indicate younger individuals may have more side effects due to a robust immune system, but we have seen similar side effects in all age groups in everyday practice and the real world, Dr. Parikh adds.

Dr. Nichols agrees. Based on preliminary information, the side effects are the same as with other mRNA boosters. mRNA vaccines tend to be less reactive in older adults. This isn’t too surprising—continuing the parallel with the flu vaccine, we don’t expect the flu vaccine to have different adverse effects even though we change the composition each year.

Related: Here's What Your Immunity Against COVID Actually Looks Like When You Get That Second Booster

What Happens If You Recently Had COVID?

Many people who have recently contracted COVID are curious whether they should wait to get boosted.

“If you feel back to your baseline or normal self you can get boosted. The only exception to that is if you have had a COVID monoclonal antibody treatment then would wait 90 days from that treatment,” says Dr. Parikh.

Dr. Nichols suggests waiting three months before getting boosted. Individuals should talk to their healthcare provider if they are high risk and think they might benefit from receiving it sooner.

What About Bivalent Boosters for Those 12 and Younger?

Currently, they are only approved for 12 and up but likely will be approved for younger age groups in the future when more data is available, Dr. Parikh explains. At this time, many of the younger individuals are still undergoing their initial immunizations.

While it doesn’t offer as much protection as receiving a booster first-hand, if we can get a large percentage of the population boosted against BA.4/BA.5 going into the winter, that should help protect people under 12 years by decreasing transmission, Dr. Nichols states. Vaccines containing the original virus still provide some protection against the variants, with that protection increasing with boosters. If your child is under 12 and hasn’t been boosted, parents shouldn’t wait and should get them boosted with the originally authorized vaccine option.

Next up: Subtle But Scary Symptoms of Long COVID That You Seriously Shouldn’t Ignore