Coronavirus Chronicles

Bivalent Boosters: Side Effects, Safety, and More

Answering your questions about the updated Covid-19 booster.

By Angela Cabotaje October 25, 2022

The new omicron-specific boosters are here, with those as young as five now eligible for the updated shot. But the uptake, even in very vaccinated King County, has been less than ideal.

"We have well over 1.5 million or more people that are eligible for the booster, but really, we're still down at about 15 percent of people actually having received it, and we'd like that, obviously, to be much higher than that," says Dr. Mark Del Beccaro, assistant deputy chief for Covid testing and immunization programs at Public Health—Seattle and King County.

There are a few reasons why this may be: pandemic fatigue, shot availability, vaccine confusion, and straight-up misinformation about the bivalent booster. Thankfully, Dr. Del Beccaro is game to bust some myths.

I already got a booster. Do I really need to get this one?

In one word, yes. We already know that the omicron subvariant BA.5 is highly contagious, and even as the strain du jour changes, preliminary evidence shows that "being up to date in your vaccine still gives you a protective effect compared to people that aren't," Del Beccaro explains. 

He likens it to a ubiquitous car safety device. "Most of us don't think twice about putting a seatbelt on in our car. We shouldn't think about entering the viral respiratory season without our Covid booster and our flu booster."

I heard this was only tested on animals. How do I know it's safe?

The original Covid vaccines and the new bivalent booster are almost exactly identical in terms of vaccine ingredients. "The only thing that was changed was to have the spike proteins that actually are specific to omicron," Del Beccaro says. And those OG Covid shots have already been administered to "literally millions if not a billion people worldwide."

It's the same situation for the annual flu vaccine, which has been doled out for decades—the formulation changes every year depending on the particular strain circulating but doesn't undergo new clinical trials or testing. "You can't test it on a million people during the season because by the time you get the results, the season is over," Del Beccaro notes.

I heard the side effects are worse with the updated shot.

Just as with the original vaccination series, your mileage may vary. Some folks tolerate the shots better than others, and Del Beccaro adds that side effects from the bivalent booster aren't different from the previous vax version. 

Silver lining if you're dreading the fatigue and muscle pain: A new paper published on October 21 suggests those who experience side effects may have a greater antibody response than those who didn't.

What about reports of people having heart problems or dying?

In the early days of the vaccine rollout, there were reports of myocarditis, or an inflammation in the heart muscle. According to a study, this was mostly noted in adolescent boys or young men, between the ages of 12 and 24. Still, this condition is rare. Of the over 192.4 million people who received the 354.1 million doses of the Covid vax, there were only 1,626 cases of myocarditis. "I have not seen any reports of an increase in myocarditis with the new vaccines," Del Beccaro says.

As for the supposed deaths due to the Covid vax and bivalent boosters, Del Beccaro says it's all about whether you're correctly interpreting the data. "An elderly person might die in a nursing home a week after getting vaccinated," he says, but you can't automatically conclude that the death was caused by the shot. All cases are reported to the Vaccine Adverse Event Reporting System and then investigated to determine the cause. That said, Del Beccaro adds, "the risk of dying and being in an ICU and in the hospital is many fold less for people that have had the vaccine."

Is it safe to get it with the flu shot or monkeypox vaccine?

Yes, it's safe—encouraged even, for sake of convenience—to get the flu shot and bivalent booster at the same time. You might experience a touch more intensity when it comes to side effects, but the shots are safe to get together.

Monkeypox has slightly different guidance. Like the Covid shots, the monkeypox vaccine has a rare, theoretical risk of myocarditis. That's why the Centers for Disease Control suggests waiting around four weeks between the two types of vaccines. That said, if you've had a high-risk exposure to monkeypox, don't delay getting that shot, even if you've recently received the bivalent booster. 

I want the bivalent booster! I just can't find an open appointment.

Del Beccaro hears you. In some parts of King County, particularly in areas of Seattle and the Eastside, availability is tight, or at least a week or two out. That's mostly due to staffing, with primary care providers and pharmacies unable to keep up with the surge in demand while also dealing with other fall vaccination drives (see: flu, monkeypox, you get the idea). In other areas of the county, like Auburn, he says, you may be able to get in much quicker. 

Some sites to check include our roundup of vaccine clinics; pharmacies at CVS, Walgreens, Bartell, Fred Meyer, Safeway, and QFC; and hospital systems like UW Medicine, Seattle Children's, and Kaiser

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