The study’s lead researcher said its findings reinforce that vaccination is safe and effective during pregnancy.PATRICK T. FALLON/AFP/Getty Images
Vaccination against COVID-19 among pregnant individuals sharply lowers the risk of hospitalization, admission to intensive care and premature births, the largest Canadian study of its kind shows.
The report analyzed outcomes from nearly 20,000 COVID-impacted pregnancies between April, 2021, and December, 2022, capturing both the Delta and Omicron waves of the virus. Data was included from eight provinces and one territory. The study was led by University of British Columbia researchers and released on Monday in the Journal of the American Medical Association.
Lead researcher Deborah Money, a professor of obstetrics and gynecology at UBC, said the study strongly reinforces that vaccination is a safe and effective measure during pregnancy that protects the parent and baby.
“This study provides additional, solid evidence that there is value in being up-to-date with your COVID vaccines for pregnancy,” said Dr. Money.
She added that the study is also unique because the research team was able to unpack whether the benefits of vaccination persisted when the virus evolved to the less severe Omicron strain after the Delta wave, during which vaccination was widespread.
“What we were able to show is even in the milder, later Omicron phase, which is what we’re living through now and we’ll see every winter some version of that coming back, that the vaccine is still helpful in reducing adverse outcomes.”
The findings are crucial for public health officials and decision-makers as vaccine guidance evolves in other countries, she said. The United States government in May, for example, announced routine COVID vaccinations were no longer recommended for healthy pregnant women and children.
This U.S. update drew widespread criticism from Canada’s medical community who have urged pregnant people to continue to get vaccinated. Canada’s National Advisory Committee on Immunization, the World Health Organization and other leading health agencies continue to recommend immunization.
The new study concluded that vaccinated people were about 60 per cent less likely than those who were not immunized against COVID to be hospitalized and 90 per cent less likely to require intensive care.
In addition to vaccination status and which COVID strain was circulating, other potential risk factors for hospitalization such as greater body mass index were noted in the study.
The continued presence of COVID and the inevitability of a future respiratory virus pandemic “makes it vital to understand the impacts of this respiratory pathogen on individuals at higher risk of severe illness, including pregnant individuals, and the role of vaccination in mitigating these risks,” the study states.
Vaccination against COVID was also linked to fewer premature births, reducing the risk by 20 and 36 per cent, respectively, during the Delta and Omicron waves.
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Notably, the analysis found that rates of premature birth were actually lower among people who were vaccinated during pregnancy, rather than before pregnancy. The same trend was observed with rates of stillbirths.
Dr. Money said it is possible that vaccination during pregnancy offered more protection because of timing. However, she said this does not mean that people should delay vaccination until pregnancy.
“If you’re intending to become pregnant, make sure you’re up-to-date. And, if you become pregnant and you’re not up-to-date, that would give you added reassurance to go ahead and take the vaccine during pregnancy,” said Dr. Money.
This study is the biggest in Canada exploring the role of vaccination in maternal and perinatal outcomes, in addition to being one of the largest globally. It was funded through the Public Health Agency of Canada, the Canadian Institutes of Health Research and the B.C. Women’s Health Foundation.
Data from all provinces and territories, excluding the Northwest Territories, Nunavut, Newfoundland and Saskatchewan, were used in the analysis. The research team is doing further examination of the data.