Booster shots are now available to every adult vaccinated against COVID-19 in the US — at least six months after vaccination with Pfizer or Moderna shots, or at least two months after Johnson & Johnson's one-shot vaccine.
If you decide to get boosted, be prepared to take it easy for about a day afterward. Mild booster-shot side effects typically begin hours after vaccination and last for about a day or two. So it's good to be prepared to rest.
Already, more than 36 million fully vaccinated people in the US have gotten boosted. The federal government's VAERS database, a passive, self-report system for post-vaccine side effects, showed that the most common issues people complained of after they got booster shots were headaches, fatigue, and fevers.
Here are the top five post-boost symptoms, according to more than 11,000 people who voluntarily logged their data into VAERS.
So far, the people who reported booster-shot symptoms in VAERS tended to be older (46% were 65 years or older), and most were female (67%). But their symptoms mirror what other studies have shown more broadly among vaccine takers of all ages and sexes, and they complement the much larger v-safe texting database, which already has vaccine-side-effect information on more than 725,900 booster doses in the US.
Generally speaking, people who got mRNA vaccines (Pfizer, Moderna) said their side effects after a third dose were milder than after a second. The most common complaint, no matter which vaccine people got, was pain at the injection site. (That complaint was so common, in fact, that people who logged their information into the open-ended describe-your-symptoms-here VAERS system were far less likely to mention it than other adverse reactions.)
Less than 10% of v-safe participants said they were unable to work after a booster. Missed school or work tended to be more common among people who switched to Moderna's boost after Pfizer's vaccine, as the former is a higher-dose vaccine that tends to come with stronger side effects, which may be linked to slightly better immune protection, some early studies found.
'Hopefully' booster shots provide stronger, longer protection
Though it's more critical for older adults to get booster shots, health experts stress that with the holidays approaching and COVID-19 cases and hospitalizations going up, boosters will help all adults stay healthier. The additional immune protection that boosters provide against infection may not be permanent, nor is it perfect without wider vaccination coverage. But the extra layer of immune confidence during the winter months, when people are gathering indoors, is one many experts say is prudent on a communitywide level.
On the individual level, getting a boost months after a primary vaccination series may also provide a stronger, longer-lasting form of protection against coronavirus infections.
At least, that's what Dr. Anthony Fauci, the director of the infectious-diseases branch of the National Institutes of Health, is hoping.
"It's referred to immunologically as affinity maturation, which means that the B-cells that will be making the antibodies have the opportunity to gain greater strength and — hopefully — greater durability," Fauci said on Monday during the White House's COVID-19 briefing, explaining the benefit of the six-month interval between second and third doses of mRNA vaccines.
He added, "I would hope, and I think there's a reasonable chance, that the durability of protection following the third dose will be longer."
