A new side effect, temporary and benign, from vaccines against Covid? Thousands of people have found that their period comes sooner or later after being vaccinated.

After having observed the effects on her cycle herself, Dr. Kate Clancy, a medical anthropologist, launched an investigation with her former colleague Dr. Katharine Lee in order to gather testimonies. This survey received thousands of responses.

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No scientist on the subject

However, no medical studies have been conducted to observe the effects of vaccines on the menstrual cycle.

In the current state of knowledge, the vaccine would therefore not have a direct effect on the rules. “What is very reassuring is that these effects seem very occasional,” says Dr. Justine Hugon-Rodin, gynecologist and obstetrician.

The observed effects do not seem serious, so according to Dr. Hugon-Rodin, there is even little chance that studies will one day be conducted on the subject. “Studying costs money, and period mismatches are still very common. “

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Stress, a factor of delay

“The menstrual cycle is very sensitive to many external events,” explains Dr. Estelle Wafo, also a gynecologist. “60% women have irregular cycles at the base. But we know that stress or anxiety can also influence. The impressions these women had can be explained by the stress of the vaccination, ”she adds.

“At the moment, we are in examination period, and many patients have a cycle jump or a lag because of this,” adds Dr. Hugon-Rodin. “Stress, sentimental breakdown, exams, weight loss, are very frequent factors in delaying or interrupting the cycle. For her, too, the stress of vaccination and the pandemic may explain these disruptions in the menstrual cycle.

These two gynecologists specify that in the absence of a study, it is very difficult to assess what proportion of women have observed this difference.

The effects of confinement

As stress can lead to cycle shifts, or even jumps, the different confinements have also created these effects. “Especially the first confinement,” says Dr. Wafo.

However, the gynecologist specifies that few patients consulted during this period. “We had little feedback. We can think that there was a significant effect on the cycles. We don’t have any data, but it’s very likely, ”she confirms.

For our two gynecologists, no vaccine had an effect on the menstrual cycle. Not even the vaccine against the papillomavirus, which has a localized action on the cervix. According to them there would therefore be very little risk that the Covid vaccine would be an exception.