The study, published in The Lancet Infectious Diseases, is one of the first to compare vaccine side effects between a group of vaccinated pregnant women, an unvaccinated group of pregnant women and a group of vaccinated non-pregnant women. “In the early stages of the COVID-19 vaccine launch, there was low vaccine uptake among pregnant women due to concerns about data availability and vaccine safety. This large study helps us better understand the safety of COVID-19 vaccines by examining health changes for a large number of pregnant women and comparing them to similar vaccinated and unvaccinated groups.” says the paper’s first author Dr. Manish Sadarangani, associate professor of pediatrics at UBC and researcher at BC Children’s Hospital. “This study adds to the growing body of evidence that COVID-19 mRNA vaccines are safe during pregnancy.” Dr. Manish Sadarangani The COVID-19 pandemic has disproportionately affected pregnant women, who are at higher risk of severe COVID-19 disease compared to non-pregnant people of a similar age. Canada’s National Advisory Committee on Immunization (NACI) recommended mRNA vaccines for pregnant women starting in early 2021. However, many pregnant women are still reluctant to get mRNA vaccine. According to the new study by the Canadian National Vaccine Safety Network, led by Dr. Julie Bettinger, Dr. Sadarangani and her colleagues at UBC and the BC Children’s Hospital Research Institute, side effects after a dose of mRNA vaccine were usually mild and less common for those who were pregnant compared to those who were not pregnant. “This large study helps us better understand the safety of vaccines against COVID-19 by examining health changes for a large number of pregnant women and comparing them to similar vaccinated and unvaccinated groups,” said Dr. Manish Sadarangani In total, 191,360 women aged 15-49 years completed a survey after their first dose of the COVID-19 vaccine and 94,937 completed the second dose survey. A “significant health event” was defined as the onset of new or worsening physical symptoms that were bad enough for the participant to miss school or work, require medical advice, and/or prevent daily activities in the previous seven days. A “serious health event” was defined as the occurrence of symptoms requiring an emergency department visit and/or hospitalization in the previous seven days. Participants were asked to self-report any health events that occurred during the seven days following each dose of the COVID-19 vaccine. An unvaccinated control group of pregnant women were asked to record any health problems during the seven days before they completed the survey. Dr. Julie Bettinger Comparing these self-report surveys, the team found that within the week of the first mRNA dose of the COVID-19 vaccine, 4% of pregnant participants reported a major health event compared to just over 6% of non-pregnant participants who were vaccinated. In the week after the second dose, just over seven percent of pregnant participants experienced a major health event compared to 11 percent of non-pregnant participants, with the most common symptoms being malaise, headache or migraine, and cold symptoms. About 3% of pregnant unvaccinated participants reported similar events seven days before completing the survey. Less than one percent of participants experienced serious health events in all groups. “Our results demonstrate that these vaccines are safe in pregnancy and, importantly, there was no increased risk of miscarriage or other pregnancy complications,” says Dr. Bettinger, professor of pediatrics at UBC and researcher at BC Children’s Hospital. “Both health care providers and pregnant women should be aware of the most common symptoms that pregnant women may experience after vaccination, such as redness/pain at the injection site, fatigue, muscle aches and headaches.” This study was funded by the Canadian Institutes of Health Research and the Public Health Service of Canada through the COVID-19 Immunity Task Force. It was conducted by researchers from the Canadian Immunization Network’s (CIRN’s) CANVAS network.
