These Three Groups of People Have More Vaccine Side Effects

Young people, women, and people who have had COVID-19 appear to have more side effects following COVID-19 vaccines.

According to TODAY, the most commonly reported side effects include sore arms, muscle aches, redness and swelling around the injection site and mild fever. The symptoms, for the most part, appear to be mild and generally disappear with a day or two. Many people report feeling sicker after the second dose of either the Moderna or Pfizer vaccines.

More women reported side effects, even serious reactions, after getting their COVID-19 vaccines. A recent study by the Centers for Disease Control and Prevention found that nearly 80% of the 7,000 people who reported side effects from the drugs were women.

According to The New York Times, the study published in February analyzed data from the first 13.7 million COVID-19 vaccine doses given in the U.S. The research showed that 79.1% of the reported side effects came from women even though only 61.2% of them received the shot.

Severe adverse reactions such as potentially deadly anaphylaxis were almost always reported by women, said the researchers, adding that the 19 individuals who suffered anaphylaxis after the Moderna shot were female, as were 44 of the 47 who had the reaction after Pfizer’s drug.

“I am not at all surprised,” said Sabra Klein, a microbiologist and professor at the Johns Hopkins Bloomberg School of Public Health. She has extensively researched how sex and gender impact the human immune system. “This sex difference is completely consistent with past reports of other vaccines.”

Klein said women should not worry about the likelihood of side effects as this means “you are mounting a very robust immune response, and you will likely be protected as a result,” she told the Times.

According to TODAY, Dr. Anne Liu, an infectious expert and clinical associate director in the Division of Allergy, Immunology, and Rheumatology at Stanford University School of Medicine, says that clinical data showing people who have already had COVID-19 had more side effects is “not that surprising.”

She explains that that when people initially get COVID-19, their bodies elicit a “new immune response” that recognizes the invading pathogen as a danger. Cells are formed to recognize and subsequently attack the invader should it strike again. This is called the “recall response,” says Dr. Liu. When a person gets the COVID-19 vaccine and has already been infected with COVID-19, their bodies react with a recall response generating more side effects.

“Instead of the first dose generating a new immune response, which can be weaker—what you’re seeing is actually a recall response,” she tells Today. “That should be faster and hopefully stronger.”

Young people are the third group who are reporting strong side effects. Liu says that is because the immune systems of young people are more robust than older populations and mount a vigorous response against the virus.

“The more robust response in young people seems to be a good thing and it correlates with young people getting coronavirus without a severe infection,’” she said, according to TODAY.