Shelli Candefi received her fine in the morning after receiving a second dose of the Morden Kovid-19 vaccine. By noon, he noticed a sore throat and body ache, and by evening, it felt like a flu.
“My teeth were cracking, but I was sweating – like wet, but frozen,” said Ms. Candefi, a medical technician at State College, Pa.
The next day, she went to work and surveyed her colleagues – eight men and seven women – about her vaccine experiences. Six women had body aches, chills and fatigue. The woman, who did not have flu symptoms, was very upset with vomiting at night.
Eight men gave separate reports. One had mild pain in his hand, headache and body ache. The two described mild fatigue and slight pain. One got a headache. And four had no symptoms.
“I work with some very tough women,” Ms. Candefi said. But “clearly, we women suffered from the severity of side effects.” She felt better after 24 hours, and is thrilled that she received the vaccine. “I wouldn’t change a thing, because it ensures that the option beats,” she said. “But I didn’t even know what to do.”
Ms Candefi has been playing out the differences between her colleagues across the country. in study Published last month, researchers at the Centers for Disease Control and Prevention analyzed safety data from the first 13.7 million Kovid-19 vaccine doses given to Americans. Of the side effects reported to the agency, 79.1 percent came from women, even though only 61.2 percent of the vaccines were administered to women.
Almost all rare anaphylactic reactions to Kovid-19 vaccines have also occurred among women. CDC Researchers Reported All 19 individuals who have experienced such a reaction to the modern vaccine are women, and 44 of the 47 women who have had a rapid response to the Pfizer vaccine.
“I’m not surprised at all,” said Sabra Klein, a microbiologist and immunologist at the Jobs Hopkins Bloomberg School of Public Health. “This sex difference is completely consistent with previous reports of other vaccines.”
In a 2013 studyScientists at the CDC and other institutions found that four times more women than men between the ages of 20 and 59 reported allergies after receiving the 2009 pandemic flu vaccine, although more men than women reported those shots. Received one more study It was found that between 1990 and 2016, women accounted for 80 percent of all adult anaphylactic reactions in vaccines.
In general, Julian G, a medical officer at the CDC’s Immunization Safety Office, said “women have more reactions to different types of vaccines”. This includes influenza vaccines given to adults, as well as some infants, such as hepatitis B and measles, mumps and rubella (MMR) vaccines.
However, this news is not bad for women. The side effects are usually mild and short-lived. And these physiological reactions are an indication that a vaccine is working – that “you’re growing a very strong immune response, and you’ll likely be protected as a result of that,” Dr. Klein said.
But why is this sex difference? Part of the answer may be behavior. Rosemary Morgan, an international health researcher at the Johns Hopkins Bloomberg School of Public Health, said it is possible that women are more likely to report side effects than men. There is no vaccine-specific research to support this claim, but men are less likely than women See doctors When they are ill, they may also be less likely to report side effects, she said.
Nevertheless, there is no question that biology plays an important role. “The female immune response differs, in many ways, from the male immune response,” said Eleanor Fish, an immunologist at the University of Toronto.
Research has shown that, compared to their male counterparts, there is more production in women and girls – sometimes infection-fighting antibodies in response to vaccines for influenza, MMR, yellow fever, rabies, and hepatitis A and B are often Grow. Strong reactions from immune fighters called T cells, Ms. G also noted. These differences are often strongest in young adults, he said, “suggesting a biological effect, possibly associated with reproductive hormones,” she said.
Sex hormones, including estrogen, progesterone, and testosterone, can bind on the surface of immune cells and effect how do they work. Exposure to estrogen weakens immune cells Production of more antibodies For example, in response to the flu vaccine.
And testosterone, dr. “Kind of beautifully immune,” Klein said. Gets a flu vaccine Less protective Sex hormones are lower in men than many testosterone in men. Among other things, testosterone Suppressed The body’s production of immune chemicals known as cytokines.
Genetic differences between men and women can also affect immunity. Many immunological genes are on the X chromosome, of which women have two copies and men have only one. Historically, immunologists believed that only one X chromosome was on in women, and the other was inactive. But research now shows 15 percent Genes survive this inactivation and are highly expressed in females.
These strong immune responses help explain why 80 percent Women suffering from autoimmune diseases. “Women have more immunity, whether it is their own, whether it is the vaccine antigen, whether it is the virus,” Dr. Klein said.
The size of the vaccine dose may also be important. Studies have shown that women absorb and metabolize drugs differently than men, often requiring lower doses for the same effect. But until the 1990s, drug and vaccine clinical trials largely excluded women. Dr. “The doses of drugs recommended are based on clinical trials involving male participants,” Morgan said.
Today women are included in clinical trials. But in new Kovid vaccine trials, side effects were not sufficiently differentiated and analyzed by sex, Drs. Klein said. And they did not test whether the lower dose could be as effective for women but produced fewer side effects.
Until they do, Drs. Klein said, health care providers should talk to women about the side effects of the vaccine so that they do not fear them. “I think there is value in preparing women that they may experience more adverse reactions,” she said. “This is normal, and there is a possibility that their immune system is working.”