New study highlights subtle side-effect of Covid vaccine

A new survey has found over 40 per cent of respondents experienced a change in their menstrual cycle after receiving a Covid-19 vaccination.

The survey results were recently published in the journal Science Advances and the survey set out to investigate the "emerging phenomenon" of changes to menstrual bleeding after inoculation.

More than 39,000 people took part in the survey conducted by the University of Illinois and Washington University School of Medicine over the course of a few months in early 2021, after Covid-19 vaccines became widely available.

The survey found 42 per cent of respondents who had a regular menstrual cycle bled more heavily than usual after the vaccine, while 44 per cent experienced no change.

More than 40 per cent of people's menstrual cycles were impacted by a Covid-19 vaccine. Source: AAP
More than 40 per cent of people's menstrual cycles were impacted by a Covid-19 vaccine. Source: AAP

"We found that increased/breakthrough bleeding was significantly associated with age, systemic vaccine side effects (fever and/or fatigue), history of pregnancy or birth, and ethnicity," the research article says.

"Generally, changes to menstrual bleeding are not uncommon or dangerous, yet attention to these experiences is necessary to build trust in medicine."

While the number of people who experienced changes to their menstrual bleeding is startling — the authors noted people who noticed a change might have been more likely to participate.

Covid-19 vaccines have been found to be safe, with little risk of serious side effects.

A study published earlier this year found there were small and temporary changes to women's periods after being vaccinated.

Dr Kate Clancy told ScienceAlert the goal of the study from University of Illinois and Washington University School of Medicine was "never to perfectly assess prevalence".

Instead, the goal was to validate people's concerns.

Dismissal of link potentially fuelled concerns

Katharine Lee, an author of the report told the New York Times it is important people know they might experience a heavier-than-usual period, so they're not scared or shocked if they do.

The article notes that vaccine trials do not typically monitor adverse events beyond seven days.

The Covid-19 vaccines have been proven to be effective. A modelling study led by Oliver Watson of Imperial College London found the shots prevented deaths on an unimaginable scale.

In the first 12 months of the global vaccine rollout, more than 4.3 billion rolled up their sleeves.

The modelling from Imperial College London estimates vaccines saved 19.8 million people from a Covid-related death.

However, as the Science Advances article pointed out, dismissing the relationship between getting vaccinated and menstrual changes could have been detrimental.

Period products are seen in a supermarket
The authors of the study said it is important people are aware of the potential of menstrual cycles being impacted by the vaccine. Source: Getty Images

"Unfortunately, dismissal by medical experts fuelled greater concerns, as both vaccine-hesitant and anti-vaccine individuals and organisations conflated the possibility of short-term menstrual changes with long-term harms to fertility," it says.

"Pundits, politicians, religious leaders, and wellness influencers worked the oft-used framing of protecting women to advise against the vaccine."

There is also no evidence to suggest the antibodies from a Covid-19 vaccine cause any problems with pregnancy or infertility in males or females.

Prof Lee also noted menstruation is often overlooked in science when it is not relevant to pregnancy.

“It gets ignored because of the structure of science,” she said according to NBC News.

“There are very few senior people in science and medicine who are not white men. It’s just not something they are thinking about as part of their lived experience.”

Do you have a story tip? Email:

You can also follow us on Facebook, Instagram, TikTok and Twitter and download the Yahoo News app from the App Store or Google Play.