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Do COVID-19 vaccines impact fertility?

Question: Since you have become my default COVID guru, did you have something on COVID-19 vaccines and fertility, particularly how it might affect your chances if you are planning to get pregnant. This keeps coming up as a reason for requesting an accommodation.  How valid is this reason?

Answer: Fear that the COVID vaccine might negatively affect fertility is pervasive.*  It’s also baseless, and an invalid reason for accommodation. First, there is no credible, biologically plausible mechanism for inactivated vaccines (like J&J, Pfizer, and Moderna) to interfere with pregnancy or fertility.  As CDC explains, “no evidence shows that any vaccines, including COVID-19 vaccines, cause fertility problems (problems trying to get pregnant) in women or men.”  But as many of us have said before, absence of evidence is not evidence of absence.  And here’s a really important update: evidence continues to accumulate showing that COVID vaccines do not impact fertility (see the synthesis of a few recent studies herein).  

Meanwhile, evidence also continues to accumulate showing that getting COVID-19 is the real danger to pregnancy outcomes and fertility.  As ScienceNews summarized in a report published last week, “pregnant women who get COVID-19 are more likely to deliver their babies prematurely and may be admitted to the intensive care unit or die at a higher rate than uninfected women, a study of studies published last year in the British Medical Journal found. And men who get COVID-19 may have lower levels of testosterone and low sperm counts after infection, and may be more likely to have erectile dysfunction, three studies show. It’s not clear whether any of those problems continue long-term.”

Synthesis of several recent studies:

  1. SARS-CoV-2 spike protein seropositivity from vaccination or infection does not cause sterility: This study of in vitro fertilization found no difference in implantation or pregnancy rates based on women’s documented seropositivity (to the spike protein) status.  It’s findings are similar to results from two other studies recently reported at the October 2021 American Society of Reproductive Medicine Scientific Congress & Expo.  This evidence adds to accumulating knowledge debunking concerns that were widely spread on the internet from a former Pfizer scientist (for more, read the discussion section of this paper).  
  2. Sperm Parameters Before and After COVID-19 mRNA Vaccination: This study assessed  semen volume, sperm concentration, sperm motility, and total motile sperm count in healthy volunteers before and after COVID mRNA vaccination, finding no meaningful difference after vaccination.  Indeed, sperm parameters were on average slightly higher (but not in a statistically significant or meaningful way) post-vaccination. 
  3. Fertility rates and birth outcomes after ChAdOx1 nCoV-19 (AZD1222) vaccination: This study analyzed pregnancies that occurred during clinical trials for AstraZeneca in three countries: UK, Brazil, and South Africa, finding ” no evidence of an association between reduced fertility and vaccination.”  Similarly, accidental pregnancy rates during COVID vaccine trials for Pfizer, Moderna, and AstraZeneca were similar between vaccinated and placebo groups in the UK.    

*Fear is so pervasive that an October 2021 Kaiser Family Foundation poll found that 66% of parents of 5-11 year olds were concerned that the vaccine might impact their child’s fertility in the future.  The U.S. Surgeon General recently released a Health Misinformation Checklist (Figure 1), which I recommend sharing widely to help folks navigate the swarming mis-information and dis-information.

Figure 1. Health Misinformation Checklist (from HHS)