Feeling terrible after your Covid shot? Then it’s probably working. | ET REALITY


New study has encouraging message for Americans avoiding Covid shots due to concerns about side effects: Chills, fatigue, headache, and malaise that may occur after vaccination may be signs of a vigorous immune response.

People who had these side effects after the second dose of the Covid vaccine had more antibodies against the coronavirus one month and six months after the injection, compared to those who had no symptoms, according to the new study. Increases in skin temperature and heart rate also indicated higher antibody levels.

“We know that vaccine uptake can be challenging, and in some cases it may be because some people have strong reactions to the vaccine,” said Aric Prather, a clinical psychologist at the University of California, San Francisco, who led the study. . .

“My hope is that this really helps alleviate some of those concerns,” said Dr. Prather, who studies how behavioral factors affect the immune system. “In fact, those symptoms, as unpleasant as they may be, may actually be working for you.”

The study was published online last week. It has not been reviewed for publication in a scientific journal. But several experts said it was well done and its results were consistent with those of other investigation.

The relative increase in antibody levels among those who experienced side effects was small and does not mean that people without symptoms do not develop a strong immune response, experts said.

“The lack of side effects should not be taken as a sign that the vaccine is not working,” said Alessandro Sette, co-director of the Center for Vaccine Innovation at the La Jolla Institute of Immunology, who was not involved in the work.

A previous study found that 98 percent of people who felt no ill effects still produced large amounts of antibodies, compared with 99 percent of those who had localized or worse symptoms, Dr. Sette said.

Still, the new results suggest that people who have a difficult time after vaccination are probably well protected against the virus. “If you’re feeling sick, chances are you’re generating a pretty reasonable immune response,” said Deepta Bhattacharya, an immunologist at the University of Arizona who was not involved in the new study.

In research published last year, Dr. Bhattacharya and his colleagues looked at vaccine responses in 2,354 people, about half of whom took a pain reliever to ease the side effects of the shot.

In mice, nonsteroidal anti-inflammatory drugs, such as aspirin and ibuprofen, severely affect alter immune responses to coronavirus. But Dr. Bhattacharya’s team found that in people, the drugs did not silence the immune response to Covid vaccines.

Not only that, but those who took a painkiller seemed to have more antibodies than those who tolerated the symptoms without medication. The most likely explanation for this is not that painkillers increase antibody levels, Dr. Bhattacharya said.

“It’s more that people who have symptoms tend to have a slightly greater antibody response than those who don’t have symptoms, and of course people who have symptoms are more likely to take pain relievers,” he said.

Other studies have also found that people with self-reported side effects, such as fever, chills, body aches, and fatigue, had a little more antibodies than those without the symptoms.

In the new study, Dr. Prather and his colleagues tracked people’s antibody levels over time. When the vaccines were introduced in December 2020, they rushed to recruit study participants through advertisements placed in newspapers, television and social media.

At the time, much of UCSF was still closed, so they took over a Pilates studio in the university’s gym, removed the equipment, and brought in phlebotomists to draw blood from participants. The scientists excluded anyone who had evidence of a coronavirus infection before or during the study.

“We knew we had this very finite window where people were rushing to get vaccinated,” Dr. Prather said. “It was just an intense moment, but we had to do what we had to do.”

The team tracked symptoms among 363 participants who received the Pfizer-BioNTech or Moderna Covid vaccines for six days after each dose, and gave some participants biometric devices to record their temperature, breathing and heart rate.

The researchers found that those who had seven different side effects, including chills, tiredness, malaise and headache, produced almost twice the levels of antibodies as those who reported no symptoms. And a change in skin temperature of just one degree Celsius predicted three times higher antibody levels six months after the second dose.

The study measured protection against the Wuhan variant, the original version of the coronavirus. The research would be difficult to do now because people have already had multiple infections or vaccines that would influence their immune responses, Dr. Prather said.

Current Covid shots are designed to protect against the XBB.1.5 Omicron subvariant, but the results should still be relevant for all iterations of the vaccines, experts said.

The rollout of Covid vaccines this fall has been bumpy, with canceled appointments and confusion over insurance coverage. But some four million Americans was shot last month, according to the Department of Health and Human Services.

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