Why younger women tend to have more of a response to vaccines

COVID-19 vaccine
Posted at 12:47 PM, Apr 28, 2021

We're hearing more about women experiencing some rare side effects after getting vaccinated.

The Centers for Disease Control and Prevention (CDC) has reported that 15 women have experienced blood clots after getting the Johnson & Johnson vaccine. Three of those cases were deadly.

The CDC’s advisory committee says the risk of blood clotting is higher among women between the ages of 30 and 39.

Up until now, only one man has experienced a blood clot and that happened during the trial.

Generally, in large medical trials, the focus is on the entire population of participants, not gender differences.

“There is a growing call to look at these differences as new vaccines and new drugs are brought out. It is something that has not been done on a widespread basis in the past. But I think that it is time and people have seen and we will probably be continuing to see differences in the way women and men respond,” said Dr. John Hammer, infectious disease specialist at the Rose Medical Center.

Other side effects have also been seen in women and weren't confined to the J&J vaccine.

There have been some cases of anaphylaxis, or allergic reactions, mostly in women after getting the Pfizer and Moderna vaccines.

Researchers are also gathering data on reports of short-term changes in menstrual cycles after the vaccine.

Chicago's public health commissioner answered questions about this on Facebook and said estrogen can elevate immune responses, which is why women, especially those younger in age, tend to have more of a response to vaccines.

“I think the fact that these minor side effects are common in vaccines in general, and the fact that they happen more commonly in women than men may be suggestive of the fact that the woman’s immune system is more robust in its response to the vaccine and this may confer better protection,” said Dr. Hammer.

Doctors emphasize that the benefits still outweigh the risk of side effects, and they encourage everyone to get vaccinated against COVID-19.