Pregnant people experienced lower rates of side effects from the COVID-19 vaccine than their non-pregnant counterparts, a new Canadian study suggests.
Canada’s National Vaccine Safety Network collected data from 191,360 vaccinated women aged 15 to 49 between December 2020 and November 2021. Researchers asked participants to report “significant health events” serious enough to causing them to miss school or work, seek medical attention, or disrupt their routines.
Of the 5,597 pregnant participants, four percent reported a significant health event within seven days of receiving their first dose of an mRNA vaccine, and 7.3 percent of the 3,108 respondents pregnant women said they had side effects from their second injections.
Among those who were not pregnant, 6.3% of 174,765 respondents reported a significant health event after dose 1, and 11.3% of 10,254 participants said they felt sick after dose two .
“One of the things that was really surprising was that the rates of these events happening in pregnant people were lower than the rates happening in non-pregnant people at the same age,” said Manish Sadarangani, lead author of the ‘article published in The Lancet. Infectious Disease Journal Thursday. “It’s very reassuring in terms of the safety of COVID vaccines and pregnancy.”
Studies of other vaccines have found that pregnant people experience side effects at about the same rate as non-pregnant people or even slightly more, said Sadarangani, a researcher at BC Children’s Hospital.
More research is needed to understand why this might not be the case for COVID-19 mRNA vaccines, Sadarangani said, but he suspects the physical transformation of pregnancy could be a factor.
“There are a lot of hormonal, immunological and physiological changes that happen during pregnancy, and some we understand, some we don’t,” she said. “I presume some of these changes are leading to these lower rates.”
Thursday’s study found that rates of serious health events after receiving a COVID-19 vaccine, such as hospitalization, were similarly rare in all groups.
There was no significant difference in the rates of miscarriage or stillbirth between vaccinated and unvaccinated participants.
Researchers are conducting a follow-up survey to see if participants experienced side effects six months after their COVID-19 vaccinations, Sadarangani said.
Pregnant people are at higher risk for complications from COVID-19, she said, so it’s all the more important that researchers continue to study how the vaccination affects them and their babies.
“All the data we have really highlights the safety of all these vaccines in pregnancy,” Sadarangani said. “Ultimately, this is the best way to protect this group of people in our population.”
This report by The Canadian Press was first published on August 12, 2022.