Women May Need Lower COVID Vaccine Doses Than Men
An Israeli study shows that women experienced side effects almost twice as much as men after shots of the Pfizer vaccine
Women experience side effects from a dose of the Pfizer vaccine against the coronavirus nearly twice as much as men, a new Israeli study has found.
The study released last month, which found that the proportion of women who reported side effects after receiving their first, second or third of dose of the Pfizer vaccination is 1.9 times that among men, was conducted in the School of Public Health at the University of Haifa by a team of researchers led by Manfred Green, professor of Epidemiology and Public Health in the School of Public Health at the University of Haifa.
“In our study almost every side effect of the COVID vaccines was more common in women,” Green told The Media Line.
He pointed out that the results could be related to differences in the immune system of the genders. “Women may have a higher reactivity of the immune system,” he said.
Professor Cyrille Cohen, head of the laboratory of tumor immunology and immunotherapy at Bar-Ilan University, told The Media Line that it is not surprising that there could be differences in side effects between women and men.
“We know than certain genes that are important for the immune response are preset on the x chromosome, and we know that immune cells react differently to sex hormones,” he said. “We can definitely say that, to some extent, the immune response in women reacts differently to infection and also to vaccines.”
Herzliya resident Melina Sluski receives a dose of the Pfizer vaccine. (Courtesy)
Green added that another possibility to be considered, albeit less likely to be a real factor, is the difference of perception of side effects that women and men may have.
Meanwhile, a report released by Israel’s Ministry of Health showed that about 10% of Israeli women who received a third shot of the Pfizer vaccine against COVID-19 experienced irregular menstrual periods after receiving the booster shot.
The Media Line spoke to several women who experienced side effects after receiving at least one Pfizer shot.
However, the vast majority said that they are willing to eventually receive a fourth shot, illustrating that women who were inoculated in the past are willing to receive another dose despite the side effects that they may experience.
Melina Slupski, a resident of Herzliya in central Israel, told The Media Line that she experienced side effects after all three doses including pain in the arm where the shot was administered and pain in different muscles of her body, together with a headache. And regardless, she is willing to receive a fourth doses in a few months.
Likewise, Shay Hen a 24-year-old woman living in Tel Aviv, told The Media Line that she experienced side effects after two out of the three doses that she has received. Among the side effects were fatigue and discomfort. However, she added, “I’m willing to receive a fourth dose if necessary.”
Cohen noted that, worldwide, millions of doses of these vaccines are being administered on men and women and follow up research should track their side effects. But so far, he said, “I don’t think that there is a reason to really discriminate between men and women.”
Cohen also said that it should be clear that: “So far, at the end of the day, in most cases the side effects of the vaccines are less severe than the side effects of the COVID disease itself.”
However, Green believes that these results should attract the attention of the vaccine manufacturers. The message that his study sends, said Green “is that when vaccines are tested, they should always produce the data of the results according to sex.”
The professor suggested that not providing data according to gender would distort the results.
“If you produce data for both sexes combined, you hide the number of side effects in women which merge into the equation with men’s and lower the average of side effects for women,” he said.
Green added that presenting the results of vaccine side effects by gender currently is not common. “Vaccine manufactures usually do not provide test results with a breakdown according to sex,” he said.
Green told The Media Line that, in past studies, he found men tend to show a higher rate of infectious diseases than women.
And that, together with this new study on side effects of vaccines, leads him to speculate that perhaps women need to get lower doses of the vaccines than men.
