Edward Jenner, considered the “Father of Vaccinology,” first demonstrated smallpox immunity in a 13-year-old boy with cowpox in 1796. Shortly thereafter, in 1798, the first smallpox vaccine was developed. It wasn’t until 1980, almost 200 years later, that the World Health Organization (WHO) declared smallpox to be a globally eradicated human disease.  

The nearly two-century time interval between the introduction of a vaccine and the eradication of a global scourge is largely due to technology and a more sophisticated medical, research, and public health infrastructure. 

But with the very first vaccine came the opportunity for the birth of vaccine hesitancy and skepticism. 

Much of the initial and subsequent skepticism stems from several consistent areas of disconnect:

·       Incomplete understanding of the “science” behind vaccination development and the vaccine vetting and approval process

·       Impact of “non-scientific” influence on health decision-making in general and vaccine choices specifically

·       Historical atrocities committed against marginalized populations and the poor in the name of science

·       Unreliable information that is not vetted and cannot be verified through the scientific method

With the approval of multiple COVID-19 vaccine products in the late-2020, it wasn’t long before the blending and blurring of vaccine information and misinformation evolved— including discussions (both scientific and non-scientific) about the impact of these vaccines on reproductive health in both men and women.  

Concerns about fertility have been identified as common reasons for vaccine hesitancy and many physicians across the clinical disciplines report that it is a frequent source of vaccine decision-making conversation with patients.  Though the information about the transmissibility, pathophysiology, treatment and outcomes associated with SARS-CoV-2 is ever-evolving, the current consensus within the scientific and clinical communities is that there is no credible, reproducible data to suggest any deleterious interaction between the currently-available vaccines on the reproductive organs and/or function of women or men. 

Basic scientists contend that there have been no identified mechanisms by which either the mRNA or viral-vector-based vaccines are able to negatively effect the normal reproductive process.

The vaccination hesitancy fueled by fertility and other reproductive health concerns is particularly relevant within the framework of rising cases and hospitalization rates among young patients.  Since January, over 95% of COVID-19 deaths and hospitalizations in the US have occurred within the unvaccinated population.  Similarly, the overall rates of vaccination have plateaued and started to consistently decline since early June, with the decline velocity currently at an alarming rate of nearly 10% each week.  COVID-19 testing rates have followed a similar trend-graph since the late-spring.  Loosening of travel, gathering, distancing and masking restrictions have furthered the vulnerability among the unvaccinated. And now the increased frequency of 'breakthrough' infections among the fully-vaccinated have provided additional risk to those opting-out of vaccination opportunities. In addition to ongoing public health measures such as masking, distancing, and “sick” isolation/quarantine, vaccination and testing are still concerned critical components in the battle to reduce transmission, hospitalization, and death.

The 'connection' between vaccination and reproductive health presently appears to be speculative, at best. Clinical case reports and other ongoing data collection and analysis suggest that COVID-19 vaccination may impact a woman’s menstrual cycle.  Evidence suggests that these menstrual cycle distortions are transient and physicians are quick to remind their patients that other vaccines similarly have the potential to disrupt the normal menstrual cycle.

One identified culprit in the discussion regarding COVID-19 vaccination and fertility involves a specific placental protein, enverin (syncytin-1) .  This protein codes for the ERVW-1 gene which is important in the development of the placenta.   The contention is that because this protein shares a very small amount of genetic information with the protein that codes for the SARS-CoV-2 spike protein, it somehow ‘confuses’ the immune system and ‘tricks’ it into attacking female reproductive structures and hi-jacking the reproductive process.  The good news is that the human immune system is sophisticated enough to effectively differentiate between the spike protein and the enverin protein.  To date, there does not appear to be any credible evidence that any of the currently available vaccine products adversely impact placental development specifically or fertility in general.

Healthcare choice is often driven by a mix of emotion and evidence-based decision-making.  Sometimes when the flood of available information includes both reliable data and information that cannot be scientifically vetted, the information can become overwhelming and confusing.  While there is no credible evidence to date that COVID-19 vaccination poses long-term, lasting or irreparable injury to human reproduction from a conception standpoint, there is consistently compelling evidence that acute SARS-CoV-2 infection places pregnant women at greater risk of severe COVID-19 infection. 

In other words, women who are pregnant and become infected are more likely to get sicker.  Similarly, the evidence suggests that acute COVID infection increases the possibility of pre-term labor, and pre-term labor can impact pregnancy outcome as well as maternal and newborn health. These risks have not been reported to be a vaccine-associated phenomenon but rather an infection-associated risk, further supporting both the CDC and WHO recommendations that COVID vaccination not be withheld in women who are pregnant.

Similarly, there are currently no credible reports about the impact of COVID vaccination on male reproductive health, testicular function or sperm production.  Data have demonstrated, however, that men with COVID infection have reported genitourinary complaints such as testicular pain.  Additionally, SARS-CoV-2 has been identified in seminal fluid and the sperm of men infected with COVID, though the impact on sperm function, egg fertilization and pregnancy outcome is unclear.  

What is also unclear is the potential impact of acute or sub-acute COVID infection on the long-term fertility of men and women, suggesting from a purely reproductive health standpoint, that the benefits of vaccination appear to outweigh the risks.

The decision to vaccinate, within the framework of an ongoing global pandemic, is as personal as it is difficult.  Access to reliable, science-driven information and trusted clinicians are both essential elements in the decision-making process.  Trusted relationships and open lines of communications with members of an individuals' healthcare team will build the necessary bridges that ensure informed vaccine decision-making.

As more data are collected and reported, there is no doubt that recommendations, guidelines and treatment algorithms will change.  Our understanding of this complex microscopic menace, like our navigation of this pandemic season, must be flexible, fluid and driven by facts and trusted, vetted and credible information.

While each individual pursues their own path to their personal vaccine decision, remain mindful of travel and gathering, hyper-vigilant with respect to distancing and masking, and maintain a personal commitment to the indisputable benefit of time-tested and easy-to-implement public health measures like hand washing and self-isolation/quarantine when sick or symptomatic.

Remember, the key to healthcare empowerment lies within a personal willingness to weigh the facts and remain in constant pursuit of the truth.

Christpher T. Conti, MD is a concierge physician at Connected Health, LLC, where he specializes in primary care medicine, sports health & wellness, aviation health, and travel medicine.