If you already have your omicron-specific Covid booster, you may have experienced some side effects. Maybe even ones that were more intense than your previous shot.
But don’t worry—experts and new data say the new traits seem to work, regardless of whether you experience moderate, mild, or no side effects.
“Don’t focus too much on the side effects, because I really think the main goal here is to get people protected. So focus on that benefit of the new vaccines,” Dr. Yvonne Maldonado, professor of diseases pediatric infectious diseases. at Stanford University School of Medicine, tells CNBC Make It.
The new boosters won approval from the US Food and Drug Administration and the CDC before completing clinical trials. But newly published data from Pfizer and BioNTech’s ongoing clinical trial provide a first glimpse of how their new traits work in humans, showing that the new boosters generated a strong immune response against BA.4 and BA subvariants. 5 omicron.
About 11.5 million Americans have rolled up their sleeves to get the booster since it was first sent out in early September, according to the latest data from the Centers for Disease Control and Prevention. More Americans could follow: About a third of American adults say they have already gotten one or intend to “as soon as possible,” according to a Kaiser Family Foundation poll released Sept. 30 .
Here’s what you need to know about the protection the new boosters provide and where side effects fit into the equation:
The new reinforcement seems to give you protection
The redesigned traits from Pfizer and Moderna are bivalent, meaning they fit the original strain of Covid and omicron BA.4 and BA.5. All Americans age 5 and older are eligible for one if they have completed their primary immunization series.
Like previous Covid vaccines, the new boosters are designed to help you fight the virus by triggering an immune response in your body. When you get a vaccine, your immune system recognizes it as something strange because it mimics a Covid infection without causing “full-blown disease,” Maldonado says.
Your immune system responds by producing an arsenal of weapons, including antibodies, memory B cells and T cells, which work together to hunt down the “foreign object” and remember how to defend against it in the future, he adds.
Pfizer says its clinical trials were successful in inducing this immune response: One week after the injection, participants had higher levels of antibodies against BA.4 and BA.5 in their blood than those who did not step before the injection. The drugmaker did not specify how much higher those antibody counts were, but said it expects to release data measuring antibody levels one month after the boost “in the coming weeks.”
These data could better measure the full protection that Pfizer’s new booster can provide against omicron subvariants. It usually takes two to three weeks for the Covid vaccines to fully boost your immunity, which can help your body prevent an infection from occurring or prevent it from progressing to serious illness.
“We know the data isn’t complete, but it’s also reassuring that after seven days you’re already seeing an increase in antibodies,” says Maldanado. “The response is very consistent with what we’ve seen in the past with other vaccines.”
What does it mean that your side effects are more severe than others?
Side effects, in this case the familiar array of muscle aches, fatigue, headaches and more, are a natural part of our immune response to a vaccine, Maldonado says. Clinical trials on earlier versions of bivalent enhancers targeting the BA.1 subvariant of omicron found that most participants experienced “mild” side effects, with much smaller percentages reporting “moderate” or “severe” side effects .
In the real world, severity appears to be “kind of a mixed bag,” Maldonado says: Some people may have a worse, similar, or milder experience compared to their previous vaccine doses. “There will be some risk of side effects. For most people, you’ll feel something, but that doesn’t mean the vaccines aren’t safe or won’t protect you,” he adds.
Dr. Peter Chin-Hong, a professor of infectious diseases at UC San Francisco, says he definitely felt some “adverse side effects” after receiving his updated booster. He notes that he got a flu shot at the same time, and while side effects from both shots are nothing new, he suggests they may have “combined” to cause a more intense experience for him.
Some studies show that the chances of experiencing side effects after receiving both shots at the same time are similar or only slightly higher than when receiving only one Covid vaccine. So there really isn’t a concrete explanation for the cases where the side effects of the new booster are more or less severe than the others.
But you shouldn’t worry, emphasizes Dr. Helen Chu, assistant professor of infectious diseases at the University of Washington: Your side effects don’t correlate with how much protection a Covid vaccine gives you. Having mild or moderate side effects doesn’t mean you’re creating a stronger immune response than people without side effects, he says.
“You’re still going to have a nice boost in antibody levels, you’re still very protected either way,” says Chu.
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