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COVID-19 Vaccines and Infertility: Fact or Fiction?

Authors: Alex Lukey, RN, WHRC Blog Co-coordinator; Arrthy Thayaparan, BSc, WHRC Blog Co-coordinator; Liisa Galea, PhD, WHRC Lead; Deborah M. Money, M.D., F.R.C.S.C.

It can be difficult to separate fact from fiction when it comes to COVID-19 vaccines, particularly in relation to fertility and reproductive health. This blog will dive into the scientific findings of these claims and bust some of the many myths circulating about the vaccines’ impact on fertility. 

Myth #1: The vaccines haven’t been tested for pregnant people or those trying to conceive

In the earlier stages of vaccine trials, people who are pregnant or trying to conceive are not included for safety. However, in large trials, such as those for the COVID-19 vaccines, there are often accidental pregnancies. While not initially planned, this data provides a natural fertility experiment.

In a paper published by Nature, “Are COVID-19 vaccines safe in pregnancy?” the control groups had 28 accidental pregnancies, and the vaccinated groups had 29 pregnancies. The vaccinated groups received Pfizer/BioNTech, Moderna and AstraZeneca vaccines in these trials.

If the COVID-19 vaccine decreased fertility, there would be fewer accidental pregnancies in the vaccinated groups than the control groups. But it turns out the chances of pregnancy were the same. Since accidental pregnancy rates were similar between groups, there is no evidence that COVID-19 vaccines decrease a person’s fertility. The problem here is that the numbers in this comparison are not sufficient to state that there is no impact, but there is no biological reason to suspect that there would be an impact and no data to support this claim.

Myth #2: The COVID-19 vaccines cause miscarriages

Not only were there no differences in the numbers of conceptions in the vaccine trials, but there was also no difference in the number of miscarriages between participants in the control and vaccinated groups.

Based on the latest research, there is no reason to believe that the COVID-19 vaccine could increase the risk of a miscarriage.

Myth #3: The COVID-19 vaccine damages the placenta

This myth is false–it rests on the belief that after receiving the COVID-19 vaccine, the body’s immune system might attack syncytin-1, a key protein necessary for the placenta’s formation. There is also the claim that the spike protein of the COVID-19 virus and syncytin-1 are so similar that the immune system might mistake one for the other. 

This claim was tested in a recent study that showed no immune cross-reaction between the spike protein and syncytin-1, dispelling the claim that there is a risk of placental injury after taking the COVID-19 vaccines.

Myth #4: mRNA vaccine technology hasn’t been tested long enough to know if it causes infertility

While mRNA is a new technology compared to other vaccine delivery methods, there have been numerous human trials using mRNA vaccines for Influenza, HIV-1, Zika, Ebola and rabies virus well before the COVID-19 pandemic.

In fact, the first human trial of an mRNA vaccine began in 2006, giving researchers almost 15 years of follow-up data. There has been no evidence suggesting long-term fertility concerns arising from the use of mRNA vaccines based on current research. 

Myth #5: mRNA vaccines change your DNA and could impact fertility

To impact DNA, a substance must enter the nucleus, or control centre, of the cell, where DNA is stored. mRNA from vaccines is not able to enter the nucleus and therefore cannot impact DNA. 

Rather, the body uses mRNA as a template to create proteins that teach the body how to fight the COVID-19 virus. 

Take-Aways

The known risks of COVID-19 to pregnant people are severe, including increased rates of intensive care admissions and more premature births. In weighing these risks alongside the latest research, professional associations are making a strong recommendation for people planning a pregnancy to receive the vaccine.

As stated by the Canadian Society of Obstetrics and Gynecology: “There is absolutely no evidence, and no theoretic reason to suspect that the COVID-19 vaccine could impair male or female fertility. These rumors are unfounded and harmful.”

The evidence is clear. The best thing to do to protect your health and the health of those around you is to get vaccinated as early as possible.