Vaccination during pregnancy safe, effective and recommended, CMAJ says

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Three and a half years since COVID-19 first emerged in Canada, what do we know about getting vaccinated while pregnant?

An article posted this week in the Canadian Medical Association Journal (CMAJ) reaffirms that vaccination during pregnancy is safe, effective and essential, with both pregnant people and the children they carry at risk of severe outcomes if they catch the virus.

The article laid out the most up-to-date medical understanding of the virus during pregnancy, as well as recommendations for receiving a vaccination while pregnant.

"All mRNA SARS-CoV-2 vaccines approved for use in Canada are recommended during pregnancy," the article states in its final point.

RISK TO MOTHER, UNBORN INFANT

The first points of the article addressed the increased danger that COVID-19 poses to a pregnant person and to their unborn infants.

The article cited a 2021-22 observational study, which found that contracting COVID-19 during pregnancy increased the risk of serious illness and death for the pregnant patient. The study in question followed 4,618 pregnant women across 41 hospitals in 18 countries, 33 per cent of whom had a COVID-19 diagnosis at some point during their pregnancy.

They found that COVID-19 in pregnancy increased the risk of severe complications or death for the mother, with more symptomatic cases causing a higher risk.

This increased risk was seen especially among unvaccinated women – vaccination was effective in preventing severe complications, including admission to an intensive care unit (ICU) or the death of the mother.

The protective effect of vaccination was highest among those who had received two doses of an mRNA vaccine and a booster shot, which was the highest amount of doses available at the time of the study.

Not only are mothers at an elevated risk from COVID-19 during pregnancy – infants are also at a higher risk of severe outcomes, the CMAJ article states.

It cited a 2020 systematic review, which looked at more than 400 studies involving pregnancy and COVID-19. The review found the risk of stillbirth to be higher if a mother had COVID-19 while pregnant. Infants were also at a higher risk of being admitted to the neonatal ICU, with around 25 per cent of babies born to women with COVID-19 requiring a transfer.

PREGNANCY AND COVID-19 VACCINES

Receiving the COVID-19 vaccine while pregnant is safe for both the mother and the baby, the CMAJ says, which recommends mRNA vaccines during pregnancy.

"SARS-CoV-2 vaccination during pregnancy has not been shown to increase the risk of miscarriage, congenital anomalies, preterm delivery or other adverse perinatal outcomes," the article stated.

The CMAJ cited a 2023 recommendation from the American College of Obstetricians and Gynecologists, which the U.S. Centers for Disease Control and Prevention and the Society for Maternal-Fetal Medicine both endorsed.

Vaccination during pregnancy also reduces the risk of infant hospital admission due to COVID-19, the CMAJ article noted, citing a 2022 study that found a maternal vaccine was 52 per cent effective at keeping an infant younger than six months old out of hospital if they contracted the Omicron variant.

Infants younger than six months old are not eligible to receive a vaccine themselves and run a higher risk of COVID-19 complications. The study found that if a mother received two doses of an mRNA during pregnancy, the transfer of antibodies provided some protection for these infants.

The effectiveness was higher during the Delta wave at 80 per cent compared to the Omicron wave. The effectiveness was also higher if mothers received their vaccination after 20 weeks of pregnancy, rather than within the first 20 weeks.

The CMAJ article concludes by noting that vaccination is recommended for those who are planning to become pregnant or who are currently breastfeeding.