COVID-19 vaccine 'disrupted the periods of thousands of women' - but changes 'short-lived'

More than 30,000 women have reported that their periods were disrupted after getting a COVID-19 vaccine, but the changes were "short-lived", a reproductive expert has said.

Dr Victoria Male, a lecturer in reproductive immunology at Imperial College London, said most women return to normal after a single cycle and there was no evidence that vaccination affected fertility.

She said the UK medicines regulator's data does not support a link between period changes and COVID-19 vaccines since the number of reports is low - both in relation to the number of people vaccinated and the prevalence of menstrual disorders.

In an opinion piece in the British Medical Journal, she said the changes were not confined to a single type of vaccine, with reports among women who had received the Pfizer, Moderna and AstraZeneca vaccines.

If there is a link between vaccines and period disruption, she said "it is likely to be a result of the immune response to vaccination rather than a specific vaccine component".

She said research into this possible reaction is needed to understand why it might be happening.

Dr Male said the reluctance of some women to get the vaccine was largely fuelled by "false claims that vaccination could harm their chances of future pregnancy".

Disinformation about the vaccine's impact on fertility has been shared by the likes of rapper Nicki Minaj, who recently claimed her cousin's friend suffered swollen testicles and became impotent after getting the vaccine.

The UK's chief medical officer, Professor Chris Whitty, said her claims were "clearly ridiculous" and "designed just to scare", adding that people who peddle such untruths "should be ashamed".

Dr Male said "failing to thoroughly investigate reports of menstrual changes after vaccination" is likely to fuel fears about fertility.

"If a link between vaccination and menstrual changes is confirmed, this information will allow people to plan for potentially altered cycles," she added.

She said "clear and trusted information" is particularly important for those who rely on being able to predict their menstrual cycles to achieve or avoid pregnancy.

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She said changes to periods were not listed on the UK medicines regulator's list of side effects from COVID-19 vaccination, which include a sore arm, fever, fatigue, muscle aches and pain.

"But primary care clinicians and those working in reproductive health are increasingly approached by people who have experienced these events shortly after vaccination," she said.

Dr Male said more than 30,000 reports of menstrual changes were made to the Medicines and Healthcare products Regulatory Agency (MHRA) under the "yellow card surveillance scheme".

She said the way the data is collected makes it difficult to draw firm conclusions.