COVID-19 Vaccine and Pregnancy

COVID-19, aka coronavirus disease, caused by the SARS-CoV-2 virus, has changed our lives in ways none of us imagined (except maybe some scientists and Bill Gates).  While we are far from the resolution of this existential crisis, the introduction of the vaccines marks a major milestone in the effort to control the spread of the virus. As of this writing, Health Canada has approved two vaccines: Pfizer-BioNTech (approved on December 9), and Moderna (approved on December 23). Each requires two doses and will be made available for free to everyone living in Canada over the course of 2021. Due to the initial limitation of vaccine supply, high-risk groups have been identified for priority administration.

Both are messenger RNA (mRNA) based vaccines,  a remarkable and fascinating approach to stimulating the body’s immune response, not only useful for fighting infectious disease but also promising for cancer treatment. mRNA vaccines can be produced and scaled far more rapidly than traditional vaccines. A detailed review of mRNA technology that predates the COVID-19 pandemic can be found here, but this is my extremely simplified version:

In contrast to traditional vaccines that introduce a portion of live or attenuated virus into your system, mRNA vaccines do not require any viral protein to be directly injected. Instead, the virus is reverse engineered, with the instructions for producing the target on the virus (specifically, the spike protein for SARS-CoV-2) coded into mRNA, which is then packaged into carrier molecules and delivered via intramuscular injection. The body’s cellular machinery translates the instructions from the mRNA to produce the spike protein, which is brought to the cell surface like a warning flag. Your immune system recognizes the spike protein as foreign and is now prepared to defend should an actual infection occur.

These vaccines have been found to be highly effective and safe in the population tested. However, as is the case with most pharmaceuticals, pregnant & lactating people were not included in these trials, nor were those who were specifically trying to conceive. The lack of evidence in these populations has led to confusion and uncertainty if those who are pregnant/trying to get pregnant should be receiving the COVID-19 vaccines.

The opinion from the UK states that pregnant individuals should not be vaccinated, and vaccination should be delayed for those trying to conceive. In contrast, the American College of Obstetricians & Gynecologists guideline “recommends that COVID-19 vaccines should not be withheld from pregnant individuals who meet criteria for vaccination.”  This is aligned with the opinion from the Society of Obstetricians and Gynecologists of Canada which states that “the documented risk of not getting the COVID-19 vaccine outweighs the theorized and undescribed risk of being vaccinated during pregnancy or while breastfeeding and vaccination should be offered.”  

For those trying to conceive, the SOGC statement, which was also endorsed by the Canadian Fertility & Andrology Society, states “It is not known whether an individual should delay pregnancy following receipt of the vaccine and a risk-benefit discussion for those planning pregnancy should occur similar to the discussion for pregnant and breastfeeding (individuals).”  The American Society for Reproductive Medicine is more direct stating, “Patients undergoing fertility treatment and pregnant patients should be encouraged to receive vaccination based on eligibility criteria. Since the vaccine is not a live virus, there is no reason to delay pregnancy attempts because of vaccination administration or to defer treatment until the second dose has been administered.”

On balance, while it is true that we don’t have specific safety data about the COVID-19 vaccine and pregnancy, it is clear from phase 3 trials that the vaccine is very safe in general. The adverse effects of the vaccine appear to mostly comprise injection site reaction, fatigue, muscle pain, and fever.

In contrast, the risks of COVID-19 infection can be deadly. Contrary to our initial impressions from the earlier days of the pandemic, more recent evidence indicates that pregnant individuals may be more severely affected, requiring invasive ventilation, with risk factors including age > 35 associated with more serious complications. In other words, if a pregnant person does become ill with COVID-19, she has a greater risk of more complications than their non-pregnant counterparts. Even for those who recover, there appear to be risks of long-term complications, as seen in some ‘long-haulers’.

In the lack of definitive data, we can only make decisions based on the best evidence available. While the risks of the vaccine are theoretical, the dangers of the infection are real. If you are eligible for the currently approved COVID-19 mRNA vaccines, rest assured that expert opinions from both the Canadian and American reproductive specialty professional societies endorse their use during pregnancy. As always, talk to your health care professionals to determine what is right for you.