Sadarangani M, Soe P, Shulha H, Valiquette L, Vanderkooi OG, Kellner JD, Muller MP, Top KA, Isenor JE, McGeer A, Irvine M, De Serres G, Marty K, Bettinger JA. Safety of COVID-19 vaccines in pregnancy: a Canadian National Vaccine Safety (CANVAS) Network study. medRxiv. Feb 24, 2022 doi: https://doi.org/10.1101/2022.02.22.22271358.
The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.
A pre-print, not yet peer-reviewed, from the CANVAS Network, by Drs. Julie Bettinger and Manish Sadarangani from the University of British Columbia and their colleagues explored the safety of COVID-19 vaccines in pregnancy among 15-49-year-olds and compared them to an unvaccinated control group, including unvaccinated pregnant people. Among the vaccinated participants, those who reported experiencing a significant health event sufficient to cause work/school absenteeism, a medical consultation and/or prevent daily activities within seven days of receiving a first dose of mRNA vaccine were slightly more likely to not be pregnant (pregnant: 4%; non-pregnant: 6.3%). The same applies after a second dose (pregnant: 7.3%; non-pregnant: 11.3%). Among 339 unvaccinated pregnant participants, 3% reported similar health conditions. This study offers reassuring evidence that there is no significant association between vaccination status and significant health issues in pregnant people. It also highlights pregnant women actually suffered fewer significant adverse events after vaccination than did similarly aged non-pregnant females.
- Comparing two groups of vaccinated women, pregnant and not pregnant, pregnancy was associated with decreased odds of a significant health condition after any mRNA vaccine, whether for dose 1 or dose 2.
- Compared to non-pregnant women, vaccinated pregnant women reported fewer significant health conditions sufficient to cause work/school absenteeism, medical consultation and/or prevent daily activities within seven days after receiving a first dose (pregnant: 4%; non-pregnant: 6.3%) and after a second dose of mRNA vaccine (pregnant: 7.3%; non-pregnant: 11.3%).
- Pregnant women have a 2.4 times increased odds ratio of having a significant adverse event after a second dose of any mRNA vaccine (primarily weighted by the high rate of significant health events post-Moderna vaccine which had an odds ratio of 4.4) compared to pregnant unvaccinated women.
- Miscarriage was the most frequently reported adverse pregnancy outcome, and was more frequently reported in the unvaccinated (n=7, 2.1%) than in the vaccinated group (n=83, 1.5%). This suggests that the vaccine did not increase the risk of pregnancy loss.
- Other adverse pregnancy outcomes, such as vaginal bleeding, abnormal fetal heart rate, and reduced fetal movement were rarely reported within seven days following any mRNA vaccination.
Researchers collected information from 191,357 vaccinated and 6,179 unvaccinated females from seven Canadian provinces and territories as of November 4, 2021. Among them, 5,595 vaccinated and 339 unvaccinated people were pregnant. This study collected data on significant and serious health events following immunization with the mRNA vaccines.