Self-reported reactogenicity after COVID-19 vaccination with and without influenza vaccine coadministration during pregnancy in Canada

BACKGROUND: Despite consistent evidence of safety and efficacy of immunization against COVID-19, vaccine hesitancy remains prevalent among pregnant individuals. Reactogenicity (post-vaccination inflammatory symptoms) has been cited as a significant factor in decreasing vaccine acceptance. The seasonal overlap in the vaccination schedule for COVID-19 and influenza provides an opportunity to increase vaccine accessibility and uptake while decreasing healthcare burden through coadministration. METHODS: The Canadian COVID-19 Vaccine Registry for Pregnant Women and Pregnant People (COVERED) is a national prospective cohort study that enrolled pregnant participants in Canada, irrespective of vaccination status, from September 2023 to March 2024. Vaccine reactogenicity and significant health events (defined as a new or worsening health problem), within seven days of COVID-19 vaccination, were assessed using serial online surveys, and compared between those who received COVID-19 vaccine only and those who received concurrent COVID-19 and influenza vaccines (coadministration). RESULTS: Among 754 participants, 344 (45.6%) received COVID-19 vaccination during pregnancy, with 85 of 344 (24.7%) also receiving a same-day influenza vaccination. Within seven days of COVID-19 vaccination, the adverse events most reported were local injection site reaction (166/344 [48.3%]), fatigue (139/344 [40.4%]), and myalgia (135/344 [39.2%]). Increased rates of COVID-19 injection site reaction (57/85 [67.1%] vs. 109/259 [42.1%], p < .01) and chills (16/85 [18.8%] vs. 22/259 [8.5%], p = .03) were reported in those who received COVID-19 and influenza vaccines together when compared to those who received the COVID-19 vaccine alone. No new or worsening health problems were reported after coadministration of COVID-19 and influenza vaccines during pregnancy. CONCLUSIONS: COVID-19 vaccination in pregnancy, with or without influenza vaccine coadministration, was safe and well-tolerated by survey respondents. Local injection site reaction and chills were more common after COVID-19 vaccination in those who also received a same-day influenza vaccination. There were no reports of significant health events after COVID-19 and influenza vaccine coadministration.