Blog Series

Ananta Seth: The link between COVID-19 vaccination and irregular menstruation was not first published in a leading science journal or in the results of a Covid-19 vaccine trial. Initially, it emerged as anecdotal evidence. Thousands exchanged their experiences of heavier periods, unexpected vaginal bleeding or missed cycles[1]. The discussion was primarily informed by people who menstruate, discussing the effects of the jab on their periods on Twitter threads and Reddit forums[2]. This confirmed that their experience of menstrual effects post-vaccination was not an isolated one.

This is hardly surprising. It is common to find clinical definitions of symptoms based on characteristics perceived in men. While medical science has proven that disease outcomes, intensity, occurrence and health system responses are varied by gender, there is a tendency to homogenize medical data and assume that studies involving men are equally applicable to women. While women were not under-represented in COVID-19 vaccine trials, most studies failed to report sex-disaggregated data or sub-group analyses.  A recent published review of Covid-19 medical literature shows that only 18 per cent of clinical studies present sex-disaggregated data or sub-group analyses[3]. Another study indicates that while a third of the studies publish sex-disaggregated efficacy data, none report safety data[4].

Men’s bodies have long been considered the “norm” in medical research. The default subject is the 70-kg, young and able-bodied white male . Women’s bodies, on the other hand, are considered outliers. It was only in 1993 that the National Institutes of Health (NIH), the US government’s primary public health research agency, included women in clinical studies. Till then, women had been excluded as their bodies were considered too complex and ‘physiologically variable’ due to hormone changes and perceived risk in women of child bearing potential. The understanding of women’s bodies continues to be severely under-researched and trialed. In 2021, 98 per cent of all marketed drugs have insufficient or no data to guide dosing during pregnancy and lactation[5].

The Pfizer-BioNTech vaccine was approved for emergency use authorization as early as December 2020. As with most clinical studies, none of the Covid-19 vaccine trials considered menstrual cycle effects. Specific studies were commissioned as late as September 2021, almost a year after national vaccination programmes were rolled-out in countries that got first access to these vaccines. The NIH recently gave grants amounting to USD 1.67 million to investigate the potential association. Some of the commissioned studies will use blood, tissue, and saliva samples collected before and after vaccination to analyze for immune or hormone changes. Other studies will use established resources — such as large cohort studies and menstrual cycle tracking apps — to collect and analyze data from racially, ethnically, and geographically diverse populations. While a step in the right direction and one that has implications on how women’s reproductive and sexual health will be dealt with in future clinical studies, the question on why women’s menstrual cycles were not tracked during the process of vaccine development is one that begs to be asked.

UK’s Medicines and Healthcare Products Regulatory Authority (MHRA) has received 34,633[6] reports of menstrual changes and two US-based researchers have collected over 140,000 reports so far. Despite this, menstrual irregularities are still not listed as a possible side effect on most countries’ official vaccine advisory and public health announcements. Vaccine hesitancy among young women is largely driven by false claims that Covid-19 vaccines could harm their chances of future pregnancy. Vaccine hesitancy in pregnancy and refusal is a longstanding issue. Concerns about the Covid-19 vaccine are centered on possible side-effects on the fetus, mistrust of vaccine efficacy and the need to get vaccinated, as well as the exclusion of pregnant women from clinical trials.

The ongoing pandemic has placed a spotlight on the overwhelming amounts of mis- and disinformation shared and spread across social networks (both online and offline) that create confusion, impact vaccine demand and prevent individuals from making sound decisions about disease prevention and vaccinations. A lack of credible information in the public domain and absence of targeted risk communication by health agencies can have profound implications on women’s confidence in vaccines and affect uptake. Detection of adverse event information among women needs to be streamlined in pandemic response strategies of governments.

The sustainable development goals recognize the importance of collecting gender sensitive and sex-disaggregated data as essential to achieving better health outcomes across all ages. Gender intersects with other factors such as age, ethnicity, poverty and geographic location, and can provide crucial insights into how an intersection with each variable can provide differentiated results. The pandemic has underlined the necessity of designing studies that take the specific gendered needs of men, women and sexual minorities into account. This requires some system-level changes such as funding agencies and trial registries requiring that studies report sex-disaggregated data. There is, however, a need to go beyond collection of sex-disaggregated data, to collecting and analyzing data in a way that unveils gendered differences in vaccine side-effects, risks and outcomes. This includes asking the right questions about women’s reproductive and sexual health during trials. A sex and gender-responsive approach to generating and reporting evidence on vaccines is urgently needed to strengthen vaccine confidence, particularly among women. And if half the population believes in the value and safety of vaccines, it has the potential to save many lives.

Note: A recent study ( December 2021) published in the British Medical Journal provides evidence that Covid-19 vaccines do not affect fertility and menstrual side-effects are temporary[7].

Footnotes

[1] https://mobile.twitter.com/Telegraph/status/1438781201536405506

[2]https://www.reddit.com/r/AskWomenOver30/comments/mwuv9d/anyone_noticing_menstrual_cycle_changes_after/

[3] Vassallo, Amy, Sultana Shajahan, Katie Harris, Hallam Laura, Carinna Hockham, Kate Womersley, Mark Woodward, and Meru Sheel. “Frontiers | Sex and Gender in COVID-19 Vaccine Research: Substantial Evidence Gaps Remain | Global Women’s Health,” January 11, 2021. https://www.frontiersin.org/articles/10.3389/fgwh.2021.761511/full.

[4] Palmer-Ross, Alice, Pavel V. Ovseiko, and Shirin Heidari. “Inadequate Reporting of COVID-19 Clinical Studies: A Renewed Rationale for the Sex and Gender Equity in Research (SAGER) Guidelines.” BMJ Global Health 6, no. 4 (April 1, 2021): e004997. https://doi.org/10.1136/bmjgh-2021-004997.

[5] Chaphekar, Nupur, Prerna Dodeja, Imam H. Shaik, Steve Caritis, and Raman Venkataramanan. “Maternal-Fetal Pharmacology of Drugs: A Review of Current Status of the Application of Physiologically Based Pharmacokinetic Models.” Frontiers in Pediatrics 9 (November 3, 2021): 733823. https://doi.org/10.3389/fped.2021.733823.

[6] As of 8 September 2021

[7] Robinson, Olga, and Rachel Scharer. “Covid Vaccine: Period Changes Could Be a Short-Term Side Effect.” BBC News, May 12, 2021, sec. Health. https://www.bbc.com/news/health-56901353.

References

ANI News. “Link between Menstrual Changes and COVID-19 Vaccination Plausible: Study,” September 19, 2021. https://www.aninews.in/news/science/link-between-menstrual-changes-and-covid-19-vaccination-plausible-study20210919201502/.

Chaphekar, Nupur, Prerna Dodeja, Imam H. Shaik, Steve Caritis, and Raman Venkataramanan. “Maternal-Fetal Pharmacology of Drugs: A Review of Current Status of the Application of Physiologically Based Pharmacokinetic Models.” Frontiers in Pediatrics 9 (November 3, 2021): 733823. https://doi.org/10.3389/fped.2021.733823.

CNA. “Vaccines Not Linked to Menstrual Changes; COVID-19, Flu Shots Can Go Together – CNA,” November 15, 2021. https://www.channelnewsasia.com/world/vaccines-not-linked-menstrual-changes-covid-19-flu-shots-can-go-together-2315711.

Gender Action Portal, HKS. “Utilizing Evidence-Based Research to Incorporate a Gendered Lens for the COVID-19 Pandemic,” n.d. https://gap.hks.harvard.edu/gap-covid19.

George Institute. “Meeting the Call for Sex- and Gender-Disaggregated Data for the Benefit of Both Women and Men Globally | The George Institute for Global Health.” Accessed December 6, 2021. https://www.georgeinstitute.org.uk/news/meeting-the-call-for-sex-and-gender-disaggregated-data-for-the-benefit-of-both-women-and-men.

Harman, Sophie. “Ebola, Gender and Conspicuously Invisible Women in Global Health Governance.” Third World Quarterly 37, no. 3 (March 3, 2016): 524–41. https://doi.org/10.1080/01436597.2015.1108827.

Holdcroft, Anita. “Gender Bias in Research: How Does It Affect Evidence Based Medicine?” Journal of the Royal Society of Medicine 100, no. 1 (January 2007): 2–3.

Jain, Shruti. “Gender-Disaggregation of Health Data Crucial in Defeating the Pandemic.” ORF. Accessed December 6, 2021. https://www.orfonline.org/expert-speak/gender-disaggregation-of-health-data-crucial-in-defeating-the-pandemic-66594/.

Male, Victoria. “Menstrual Changes after Covid-19 Vaccination.” BMJ 374 (September 16, 2021): n2211. https://doi.org/10.1136/bmj.n2211.

Murali, Malavika. “Possible Link between Covid Vaccine and Disruption in Menstrual Cycle: Study.” Hindustan Times, September 20, 2021. https://www.hindustantimes.com/lifestyle/health/possible-link-between-covid-vaccine-and-disruption-in-menstrual-cycle-study-101632104164018.html.

Palmer-Ross, Alice, Pavel V. Ovseiko, and Shirin Heidari. “Inadequate Reporting of COVID-19 Clinical Studies: A Renewed Rationale for the Sex and Gender Equity in Research (SAGER) Guidelines.” BMJ Global Health 6, no. 4 (April 1, 2021): e004997. https://doi.org/10.1136/bmjgh-2021-004997.

Perez, Caroline. “Why Didn’t Doctors Listen to Women about the Link between Covid Vaccines and Periods?,” September 17, 2021. https://www.telegraph.co.uk/women/life/didnt-doctors-listen-women-link-covid-vaccines-periods/.

Purdie, Anna, Sarah Hawkes, Kent Buse, Kristine Onarheim, Wafa Aftab, Nicola Low, and Sonja Tanaka. “Sex, Gender and COVID-19: Disaggregated Data and Health Disparities – BMJ Global Health Blog,” March 24, 2021. https://blogs.bmj.com/bmjgh/2020/03/24/sex-gender-and-covid-19-disaggregated-data-and-health-disparities/.

Robinson, Olga, and Rachel Scharer. “Covid Vaccine: Period Changes Could Be a Short-Term Side Effect.” BBC News, May 12, 2021, sec. Health. https://www.bbc.com/news/health-56901353.

UK Gov. “Conditions of Authorisation for COVID-19 Vaccine Pfizer/BioNTech (Regulation 174).” GOV.UK, March 12, 2021. https://www.gov.uk/government/publications/regulatory-approval-of-pfizer-biontech-vaccine-for-covid-19/conditions-of-authorisation-for-pfizerbiontech-covid-19-vaccine.

Vassallo, Amy, Sultana Shajahan, Katie Harris, Hallam Laura, Carinna Hockham, Kate Womersley, Mark Woodward, and Meru Sheel. “Frontiers | Sex and Gender in COVID-19 Vaccine Research: Substantial Evidence Gaps Remain | Global Women’s Health,” January 11, 2021. https://www.frontiersin.org/articles/10.3389/fgwh.2021.761511/full.