A new Canadian study has found that COVID-19 mRNA vaccines are safe to use in pregnancy and that pregnant people experienced lower rates of significant or serious health complications after taking the vaccine than non-pregnant vaccinated people of similar age.
Within the week of the first mRNA COVID-19 vaccine dose, four per cent of pregnant participants surveyed reported a significant health event compared to just over six per cent of non-pregnant vaccinated participants, according to the study published in The Lancet Infectious Diseases Thursday.
The researchers of the study — led by the University of British Columbia (UBC) and BC Children’s Hospital — looked at a total of 191,360 women aged 15-49 who were asked to complete a survey after their first dose of COVID-19 vaccine, and 94,937 women after getting the second dose.
Participants were asked to self-report any health events, be they serious or significant, that occurred during the seven days following each dose of the COVID-19 vaccine.
The researchers defined a significant health event as experiencing new or worse physical symptoms bad enough to make the participant miss school or work, require medical consultation, or prevent daily activities.
On the other hand, a serious health event was defined as experiencing symptoms that required a visit to the emergency department and/or hospitalization.
In the week following a second dose, just over seven per cent of pregnant participants experienced a significant health event compared to 11 per cent of non-pregnant participants, with the most common symptoms being feeling unwell, headache or migraine, and cold symptoms.
The study also found that approximately three per cent of pregnant unvaccinated participants reported similar events seven days before completing the survey.
Fewer than one per cent of participants experienced serious health complications in all groups.
Dr. Manish Sadarangani, an associate professor of pediatrics at UBC and investigator at BC Children’s Hospital, told Global News that the baseline assumption he and his team had before conducting the study was that the COVID-19 mRNA vaccines are safe to use during pregnancy.
“That assumption is based on a very long history of giving vaccines (to pregnant people) … and a lot of those are classified as ‘non-life’ vaccines, which means there are no living parts of bacteria or viruses in them similar to all of the COVID-19 vaccines being used that don’t include any living part of the virus,” said Sadarangani.
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He said many vaccines are given safely to pregnant people, like the influenza vaccines and the pertussis vaccine (also known as whooping cough).
“There is a current recommendation that ‘live vaccines’ — so things like measles, mumps, rubella vaccine and chickenpox vaccines — should not be given in pregnancy. But actually, even then, there’s not a lot of data suggesting that they’re not safe. I think a lot of it is based on theoretical concerns and just trying to minimize risk,” said Sadarangani.
He said that in the early stages of the COVID-19 vaccine rollout, there was low vaccine uptake among pregnant people due to concerns about data availability and vaccine safety, but this study confirms and provides the reassurance that COVID-19 mRNA vaccines are safe to use.
“This large study helps us better understand the safety of COVID-19 vaccines by looking at changes in health for a large number of pregnant people and comparing that to similar vaccinated and unvaccinated groups … This study adds to the growing body of evidence that COVID-19 mRNA vaccines are safe during pregnancy,” he said.
Dr. Julie Bettinger, a pediatrics professor at UBC and investigator at BC Children’s Hospital, said the results of the study show that the vaccines posed no increased risk of miscarriage or other pregnancy complications.
“Both health-care providers and pregnant people should be aware of the more common symptoms pregnant people may experience after vaccination, including redness/pain at the injection site, fatigue, muscle aches and headaches,” she added.