Canadian researchers are examining the safety and effectiveness of COVID-19 vaccines among pregnant and breastfeeding women, as well as the health of mothers and their babies in the case of pregnant women who were immunized or not.
One national study led by researchers in British Columbia is looking at women's attitudes toward vaccination as well information on other health factors and adverse effects from immunization and how a pregnancy has proceeded.
A second study in Ontario is monitoring the health of mothers and their babies as researchers compare people who were vaccinated during pregnancy, or just before, with those who were not immunized.
Both studies, with $1.3 million in federal funding, are aimed at giving women, health-care providers and provincial vaccine advisory committees the data they need to guide decisions and recommendations about vaccines.
Dr. Deborah Money, who is leading the national study, said women will answer questions in a series of modules to provide information on whether they were vaccinated, received one dose or two doses, and if they were infected with COVID-19 so outcomes can be compared among all the participants.
She said that while pregnant and breastfeeding women were excluded from initial clinical trials on vaccines, real-world evidence suggests immunization is safe during pregnancy and further studies are needed specifically for Canada's population.
"There are a couple of small studies that the vaccine companies are running, none of which are in Canada yet, to my knowledge, that are including pregnant women," said Money. "But they're having difficulty because the vaccine essentially has rolled out for pregnant women already and they can't run their usual placebo-controlled trials ethically."
Money, a professor in the department of obstetrics and gynecology at the University of British Columbia, said about 4,000 women have already registered in the study and she's inviting people from across the country to participate.
Data from a different ongoing national study led by Money suggests pregnant women are at a significantly higher risk of being hospitalized and ending up in intensive care and on a ventilator compared with the general population in their age group due to changes in immune response during pregnancy.
"There are also physiologic changes of pregnancy that seem to result in more susceptibility to more serious respiratory infections and we saw that actually with H1N1 and other flu pandemics that pregnant women got more seriously ill," she said.
The Society of Obstetricians and Gynecologists of Canada as well as a national vaccine advisory panel have recommended vaccines for women who are pregnant or breastfeeding and several provinces, including B.C., Ontario, Saskatchewan, Manitoba, Quebec and New Brunswick have prioritized pregnant women for immunization.
The Ontario-based study will link information collected from all births in that province since last December, when vaccines became available, with Ontario's vaccination registry to monitor the health of mothers and their babies.
Lead researcher Dr. Deshayne Fell, a scientist at the CHEO Research Institute and associate professor at the University of Ottawa, said the data will be made available on an ongoing basis during the estimated two-year study period so women can make informed decisions about vaccination.
"I think it's terrible for anybody to be so severely ill that they're in an ICU and ventilated. It's much more complicated to have that kind of clinical disease severity in a pregnant person, so with ventilation and pregnancy it's really complex," she said. "Care providers are concerned about the welfare of their patients and obviously you want to make sure that pregnant women at least have the opportunity to be protected."
Some international studies have found that a mother's vaccine-induced immunity can transfer to her infant, similar to what's been seen with the influenza and pertussis or whooping cough vaccines, both of which are routinely recommended to pregnant women, said Fell, who is also involved in the new study led by Money.
Fell said that while the Centers for Disease Control and Prevention in the United States has released some data on vaccines and pregnancy, differences in the Canadian population, including racial ethnicity composition, underscore the need for studies in Canada.
"Our health-care system is different and pregnancy outcomes are a little bit different. For instance, in the United States, they have slightly higher rates of preterm birth than we tend to have here in Canada. Just the whole dynamics of the pandemic itself are very different here."
About 6,035 pregnant women in Canada have been infected with COVID-19 based on data to the end of April, and about 95 women ended up in hospital across the country, though up-to-date information from Quebec and Saskatchewan is not available, Fell said.
Studies from around the world suggest pregnant women who were admitted to hospital or required ventilation due to COVID-19 infection tended to have babies earlier and that those babies were smaller in size than those of their healthy counterparts, she said.
Some research also found a higher risk of stillbirth with a COVID-19 infection during pregnancy, she added.
This report by The Canadian Press was first published May 19, 2021.
