- Newly approved bivalent booster vaccines targeted at Omicron subvariants may prompt a similar group of side effects noted by researchers in earlier formulations.
- Americans shouldn’t expect to experience brand new side effects or symptoms and are less likely to have a severe reaction to this new booster vaccine.
- Those who have recently recovered from a COVID-19 illness also have special directives to consider before receiving a booster shot, which are outlined below.
Americans are learning more about the new set of bivalent COVID-19 booster vaccines made by teams at Pfizer and Moderna after officials at the Food and Drug Administration (FDA) authorized its rollout earlier this month. With clinics and pharmacies across the nation (including CVS and Walgreens) now offering vaccination appointments, you may be curious to know more about this updated vaccine and what kind of side effects may be affecting you after the shot.
If you haven’t heard of the term “bivalent” just yet, it refers to the fact that this updated vaccine contains genetic code targeted to the original strain of virus that spreads COVID-19, known as SARS-CoV-2 — in addition to parts of the Omicron-based strains that are circulating currently.
“Half of it is the same as the original vaccine,” explains Richard Martinello, M.D., the medical director of infection prevention at Yale New Haven Health System. “The other half is focused on the new sub-variants that have been causing nearly all the disease we’ve been seeing over the past few months.”
Scientists have readily admitted that this particular batch of bivalent vaccines, targeted towards BA.4 and BA.5 sub-Omicron variants, have yet to be studied in humans officially. But you shouldn’t be worried about any increase in side effects here, Dr. Martinello explains, as FDA regulators have seen a similar bivalent booster vaccine made by Pfizer and BioNTech for the “stealth” Omicron variant that spread rampantly last winter — and those bivalent boosters were extensively studied before they were rolled out. Current authorizations are based on these previous studies, as laid out by health regulators at the Centers for Disease Control and Prevention (CDC).
“The data that was already generated from the bivalent BA.1 vaccine, the human data, really gave the FDA the confidence that they could approach approving this new bivalent shot,” Dr. Martinello says, adding that this kind of approval system is similar to the annual flu vaccine.
What does available data suggest about any side effects of a bivalent booster compared to a primary COVID-19 vaccine or earlier boosters administered in 2021? Virologists and vaccine experts explore what we know below.
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Potential Omicron bivalent booster vaccine side effects:
Data collected by the FDA for earlier bivalent COVID-19 booster vaccines suggests that these shots successfully provided immunogenicity (a boost to your immunity!) and elicited consistent side effects as compared to other COVID-19 vaccines, according to Dr. Martinello.
Sherrill Brown, M.D., medical director of infection prevention for AltaMed Health Services, indicates that current side effect notices published by the FDA sourced data from both Pfizer and Moderna’s separate clinical trials for the earlier BA. 1 vaccines. In both trials, the most commonly reported side effects within a week of injection were:
- Pain at the injection site, alongside redness and/or swelling
- Extended fatigue
- Widespread muscle pain
- Joint pain
- Nausea and vomiting
According to current FDA publications, there’s also a chance that swelling may occur in lymph nodes within the same arm as the injection site.
You’ll notice that all of these side effects warnings are the same that came with original vaccine formulations. But it’s interesting to note that the severity of side effects caused by bivalent vaccines were reported as less severe; Pfizer’s clinical trial found that less than 1% of patients experienced severe pain or headaches, whereas a majority of participants (52%) reported only mild pain at the injection site.
Similar figures were true for Moderna recipients, as 59% of patients indicated they’d experienced fatigue after their shot, but only 4% reported it at a severe level.
It’s expected that the likelihood of severe side effects caused by COVID-19 vaccines will decrease as patients receive more boosters over the next few years, Dr. Brown explains. “Some rare side effects such as myocarditis and pericarditis have been shown to be even less common with subsequent booster doses compared to the primary series second dose shot,” she adds.
Will I experience a similar reaction after my 4th vaccine as earlier ones?
Both federal health officials and leading virologists polled by Good Housekeeping for this article suggest that you should expect similar side effects this time around if you experienced them after earlier vaccinations. Since the formulation of this particular round of bivalent booster vaccines was made in a very similar process to earlier options, experts aren’t expecting any new subsets of potential side effects to present this fall.
Shruti Gohil, M.D. associate medical director of infection prevention at UCI Health and a professor at the University of California, Irvine, posits an analogy that this bivalent vaccine is like a riff on a standard brownie recipe: “You’re going to have almost the same ingredients, and bake it for the same time at the same temperature — but this time, instead of just chocolate chips, you add dark chocolate, too,” she tells Good Housekeeping. “The resulting brownie is the same, though.”
It’s important to note that individuals will react to these bivalent booster vaccines differently — while the most common side effect is pain or swelling at the injection site, many people may feel more severe side effects, and unique combinations of the symptoms listed above. And if you didn’t experience any side effects at all during your initial vaccine series or from the boosters after, there’s a good chance you won’t this time around, either.
“There’s no way for us to predict how somebody is going to respond, but we know that the spectrum of severity is the same as what we’ve seen with original vaccines,” Dr. Martinello adds. “We do not expect [the public] to experience anything that would be out of the ordinary from our experience with the original vaccination.”
Will side effects be different for anyone who has recently recovered from COVID?
While it’s not a hard-and-fast rule, CDC officers have made recommendations to Americans to consider delaying receiving this bivalent booster vaccine at least three months from the date of your last COVID-19 infection. According to materials published by the American Medical Association, research on the timing between infection and another injection indicates that an increased timeline in this range could better bolster your body’s immune response compared to receiving a shot earlier.
But if you do choose to receive a bivalent booster within three months of your last sickness, you shouldn’t expect to experience wildly different or worse side effects as compared to if you had waited, Dr. Martinello stresses. You also shouldn’t expect a lighter immune response, either.
“I encourage people who have had COVID — once, or even multiple times — to still seek out vaccination, as it’s going to really optimize the level of protection that you have against getting COVID yet again this fall and winter,” he advises.
The bottom line:
Experts aren’t expecting a dramatic shift in side effects triggered by new COVID-19 bivalent booster vaccines targeted toward Omicron spread. Those receiving a bivalent booster and notice side effects within a week of injection are recommended to do the following by CDC officials:
- Rest as much as possible
- Drink plenty of water and other better-for-you fluids to stay hydrated
- Take over-the-counter medication like ibuprofen, acetaminophen, aspirin, and antihistamines as needed
- Apply a cold compress or a wet washcloth over the injection site if experiencing redness or swelling
- Exercise your arm after injection to mitigate discomfort
Dr. Brown believes that this will not be the last time a new booster vaccine is offered to the American public — in fact, experts are projecting that annual vaccines against the spread of COVID-19 may become commonplace soon.
“I expect the COVID-19 booster shot to become an annual recommendation with small changes needed each year to keep up with, and protect against, new variants that arise,” she explains. “This is a similar process that we go through with our annual influenza vaccination.”
As more information about the coronavirus pandemic develops, some of the information in this story may have changed since it was last updated. For the most up-to-date information on COVID-19, please visit online resources provided by the CDC, WHO, and your local public health department.
Zee Krstic is a health editor for Good Housekeeping, where he covers health and nutrition news, decodes diet and fitness trends and reviews the best products in the wellness aisle. Prior to joining GH in 2019, Zee fostered a nutrition background as an editor at Cooking Light and is continually developing his grasp of holistic health through collaboration with leading academic experts and clinical care providers. He has written about food and dining for Time, among other publications.
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