COVID-19 Infection and Vaccination During Pregnancy

October 8, 2021

Authors: Jennifer Richard, PhD, Department of Psychology, UBC; Liisa Galea, PhD, WHRC Lead | Editors: Negin Nia and Arrthy Thayaparan (Blog Coordinators) 

Published: October 8th, 2021

Pregnancy is a vulnerable time for infection due to dynamic changes to the immune system leading to reduced immunity. This also implies an increased risk of people becoming severely sick after contracting COVID-19 (SARS-CoV-2) while pregnant. In fact, COVID-19 infection during pregnancy increases the risk of intensive care (ICU) transmission for the mother, preterm birth, caesarean (c-section) delivery, and admission to neonatal care for the baby. These risks are worsened by the Delta variant, currently the most common variant in Canada, which is up to twice as contagious as previous variants. The rise in Delta variant infections has increased the proportion of pregnant people with severe infection compared to previous variants. More specifically, Delta increases the risk of pregnant people requiring respiratory support, contracting pneumonia, and being admitted to intensive care. 

How can we protect pregnant people from COVID-19 infection and related complications?

The best protection, whether you’re pregnant or not, is getting vaccinated. However, the Center for Disease Control and Prevention (CDC) reported that only about 25 per cent of pregnant people in the U.S. have received at least one COVID-19 vaccine dose. Several studies have demonstrated that two doses of AstraZeneca-Oxford and Pfizer-BioNTech COVID-19 vaccines are still effective in preventing severe disease, hospitalization, and death, even against Delta. 

Recent studies suggest that two doses of these vaccines provide between 88-95 per cent effectiveness in protecting against the Delta variant. Whether one dose of COVID-19 vaccine is sufficient to protect against Delta is inconclusive. One study reported barely detectable levels of neutralizing antibodies against Delta after one dose of vaccine. On the other hand, a Canadian paper, that has yet to be peer-reviewed, states that one dose of Pfizer-BioNTech, Moderna or AstraZeneca-Oxford provides “good to excellent protection against symptomatic infection and severe outcomes” against Alpha, Beta, Gamma and Delta variants. However, the study also reported reduced protection against Delta compared to the other variants. 

Vaccination is also recommended for individuals who have been infected by COVID-19.  The vaccination provides superior protection compared to previous infection by another COVID-19 variant.  So, despite the Delta variant affecting vaccine effectiveness, vaccinations still remain our best form of protection for severe illness, hospitalizations, and death. This is along with maintaining social distancing, masks, indoor ventilation, and hand hygiene. 

COVID-19 vaccine hesitancy and safety in pregnancy

Women tend to be more hesitant towards COVID-19 vaccination than men or gender diverse individuals, with pregnant people reporting an even lower intention of getting vaccinated. The greatest concerns of pregnant people regarding the vaccines are a lack of data on pregnancy safety regarding the vaccines and/or that the vaccine may be harmful for their baby. So what do we know about the safety of COVID-19 vaccines in pregnancy? Can it cause pregnancy loss, affect your chances of conceiving, or alter your genes or the genes of your baby?

Is it safe to get vaccinated against COVID-19 while pregnant?

Pregnant people weren’t included in the initial COVID-19 vaccine trials. However, over 156,000 pregnant people have now been vaccinated with Pfizer-BioNTech or Moderna vaccines in the U.S. with no raised safety concerns. More specifically, the risks for adverse effects relating to pregnancy, including pregnancy loss, birth defects or effects on birth weight, were the same, or lower, than risks reported prior to the pandemic. 

Importantly, while the risk of preterm birth was not increased after vaccination against COVID-19, this risk was increased in non-vaccinated pregnant people infected by the COVID-19 virus. As for the more immediate side effects after vaccination, pregnant people reported having a slightly sorer arm (around the injection site). But otherwise, pregnant people actually reported having milder side effects than non-pregnant people, for side effects such as headaches, muscle soreness and fever. 

But are COVID-19 vaccines effective in pregnant people?

Although pregnancy causes changes to your immune system, COVID-19 vaccination in pregnant and lactating people provides the same level of immunity against the COVID-19 virus compared to vaccination in non-pregnant people. The level of protection is equal across all three trimesters, as vaccination during the first, second and third trimester gives rise to the same level of antibodies produced against COVID-19. In addition, the level of protection in all vaccinated individuals (non-pregnant, pregnant and lactating) was higher than levels observed in pregnant people who had previously been infected by the COVID-19 virus, indicating that even those who have previously been infected by COVID-19 should get vaccinated.

Can COVID-19 vaccines affect your risk of becoming pregnant?

There is no evidence that vaccination against COVID-19 would affect fertility. In males, COVID-19 vaccination does not result in a reduction in semen volume, sperm concentration or motility. In females, embryo implantation rates were the same as in non-vaccinated individuals. In addition, COVID-19 vaccines can not reach or cross the placenta, they act in the muscle where the vaccine is given. And even if the vaccines could reach the placenta, they can not induce antibodies against, affect or injure the placenta. However, placentas from people who tested positive against the COVID-19 virus during pregnancy showed abnormal blood flow between mother and baby. These data indicate that vaccination during pregnancy is safer than getting infected with COVID-19 during pregnancy. 

Since the vaccine rollout, thousands of individuals included in the V-safe Pregnancy Registry have reported becoming pregnant after vaccination. In addition, the rate of accidental pregnancies in vaccinated and unvaccinated individuals were reported at equal levels -- showing that vaccines don’t impact pregnancy.

Can the vaccines alter your DNA or the DNA of your baby? 

No, vaccines cannot alter your DNA. Pfizer-BioNTech and Moderna are the two most common COVID-19 vaccines given to pregnant people. They are referred to as mRNA vaccines, which carry information (mRNA) to make a part of the COVID-19 virus (spike protein). They can only make a part of the virus, and not the complete virus. The components of the vaccine can’t cause infection in the mother or baby. Neither can they alter your DNA, or the DNA of your baby (mRNA does not alter DNA). The vaccines don’t contain DNA and human cells don’t have the ability to transform RNA to DNA, only the other way around. Therefore, these vaccines are not able to integrate into your DNA, or the DNA of your baby, or cause long-term genetic changes. As an aside – if we could change DNA with mRNA we would already have cures for genetic illnesses such as cystic fibrous or Huntington’s disease.

Can vaccination benefit your baby?

The vaccine provides protection to the baby in the womb indirectly, by lowering the risk of severe sickness in the mother. In addition, COVID-19 vaccination can directly protect your unborn and/or newborn baby, because protective antibodies against COVID-19 cross the placenta, and provide protection against COVID-19 to the baby at birth. In addition, COVID-19-specific antibodies have been found in the umbilical cord of babies, and breast milk, of mothers who were vaccinated during pregnancy. 

While cases in babies and small children reported so far have been uncommon, and often cause mild to moderate symptoms, the Delta variant has proven to be more harmful to children. In the U.S., COVID-19 hospitalization rates in children and adolescents increased nearly 5-fold in late summer, a time in which Delta has been the predominant circulating variant. In a recent study from Israel, over 10 per cent  of children who were diagnosed with COVID-19 reported symptoms of long COVID, such as continued illness, fatigue or breathlessness. In addition, 30 per cent of parents of affected children reported a decline in “neurological, cognitive, and mental health abilities” compared to prior to COVID-19 infection, for example disturbed sleep and concentration problems. Furthermore, we do not yet know potential long-term effects on children whose mothers were infected while pregnant. Although rare, there are a few cases of newborns born to COVID-19 positive mothers that were tested positive for the virus at birth.This indicates that transmission of COVID-19 from mother to child during pregnancy is possible. Furthermore, the fetus can still be affected by stress, restricted oxygen, reduced placental function and sickness in the mother infected by COVID-19, in addition to the increased risk of preterm birth and c-section delivery.

Taken together, the vaccines provide great protection against symptomatic infection and severe outcomes. Recent data indicates that you are almost 30 times more likely to end up in the ICU if you are unvaccinated. Furthermore, vaccination against COVID-19 during pregnancy is effective, and far safer than the risk of contracting the virus itself, which, while rare, has a 15 times greater risk of death during pregnancy. Vaccination during pregnancy can also benefit the baby by protecting them from indirect effects of disease in the mother, and by providing antibodies against COVID-19. Not to mention it will protect you after giving birth and protect your community. The data overwhelmingly support vaccination during pregnancy as safe and effective. 

So, the bottom line is: if pregnant people are concerned about their safety or the safety of their unborn child, getting the shots (of COVID-19 vaccine) is their best shot.

Feature image by Dr. Jennifer Richard

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First Nations land acknowledegement

We acknowledge that the UBC Point Grey campus is situated on the traditional, ancestral and unceded territory of the xʷməθkʷəy̓əm (Musqueam) people.

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