Scientific basis of Covid vaccine induced menstrual irregularities

Since the earliest days of the Covid vaccine rollout women have been reporting disturbances with their reproductive health, including their menstrual cycle.

Despite early and persistent claims from governments and fact-checkers that such an association is merely coincidental, the growing body of scientific evidence confirms both that such health impacts are indeed occurring and the biological mechanism by which the vaccines are causing them.

The latest is an Israeli study published in npj Vaccines which describes how Covid vaccines can directly affect ovarian cells, and thus impact menstruation. The study, published on 26 June 2024 and titled “The direct effect of SARS-CoV-2 virus vaccination on human ovarian granulosa cells explains menstrual irregularities”, can be read online at doi:10.1038/s41541-024-00911-2.

This comes on the back of numerous other scientific studies which confirm the link between Covid vaccination and menstrual changes, including:

  • “Menstruation and covid-19 vaccination”, BMJ, 376:o142, 26 January 2022, doi:10.1136/bmj.o142
  • “Investigating trends in those who experience menstrual bleeding changes after SARS-CoV-2 vaccination”, Science Advances, 8(28), 15 July 2022, doi:10.1126/sciadv.abm7201
  • “Menstrual irregularities and vaginal bleeding after COVID-19 vaccination reported to v-safe active surveillance”, The Lancet Digital Health, 4(9), 9 August 2022, doi:10.1016/S2589-7500(22)00125-X
  • “COVID-19 vaccination and menstruation”, Science, 378(6621), 17 November 2022, doi:10.1126/science.ade1051
  • “Menstrual abnormalities after COVID-19 vaccines: a systematic review”, Vacunas, 23(2), 19 July 2022, doi:10.1016/j.vacun.2022.07.001
  • “Menstrual cycle disturbances after COVID-19 vaccination”, Women’s Health, 18, 7 July 2022, doi:10.1177/17455057221109375
  • “Premenstrual and menstrual changes reported after COVID-19 vaccination: the EVA project”, Women’s Health, 18, 14 July 2022, doi:10.1177/17455057221112237
  • “Effect of COVID-19 vaccination on the timing and flow of menstrual periods in two cohorts”, Frontiers in Reproductive Health, 4:952976, doi:10.3389/frph.2022.952976
  • “A prospective study of the association between SARS-CoV-2 infection and COVID-19 vaccination with changes in usual menstrual cycle characteristics”, American Journal of Obstetrics & Gynecology, 227(5), 13 July 2022, doi:10.1016/j.ajog.2022.07.003

Further studies can be found on the React19 scientific database at

Scientific basis of Covid vaccine induced menstrual irregularities
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