In this study of healthcare workers who received a COVID-19 vaccine, an influenza vaccine, or both, co-administration was not associated with substantially inferior immune response or to more frequent adverse events compared with COVID-19 vaccine administration alone, supporting the co-administration of these vaccines.

Gonen, et al. (2023) sought to compare the reactogenicity and immunogenicity of COVID-19 and influenza vaccinations administered together with those of COVID-19 vaccination alone.

This prospective cohort study included healthcare workers at a large tertiary medical center in Israel who received the Influvac Tetra (Abbott) influenza vaccine (2022/2023), the Omicron BA.4/BA.5–adapted bivalent (Pfizer/BioNTech) vaccine, or both. Vaccination began in September 2022, and data were collected until January 2023. Vaccines were offered to all employees and were co-administered or given separately. Adverse reaction questionnaires were sent, and serologic samples were also collected.

This study included two cohorts for two separate analyses. The reactogenicity analysis included 588 participants (of 649 questionnaire responders): 85 in the COVID-19 vaccine–alone group (median [IQR] age, 71 [58-74] years; 56 [66%] female); 357 in the influenza vaccine–alone group (median [IQR] age, 55 [40-65] years; 282 [79%] female); and 146 in the co-administration group (median [IQR] age, 61 [50-71] years; 81 [55%] female). The immunogenicity analysis included 151 participants: 74 participants in the COVID-19 vaccine group (median [IQR] age, 67 [56-73] years; 45 [61%] female) and 77 participants in the co-administration group (median [IQR] age, 60 [49-73] years; 42 [55%] female). Compared with COVID-19 vaccination alone, the risk of systemic symptoms was similar in the co-administration group (odds ratio, 0.82; 95% CI, 0.43-1.56). Geometric mean titers in the co-administration group were estimated to be 0.84 (95% CI, 0.69-1.04) times lower than in the COVID-19 vaccine–alone group.

The researchers concluded that co-administration was not associated with substantially inferior immune response or to more frequent adverse events compared with COVID-19 vaccine administration alone, supporting the co-administration of these vaccines.

Reference: Gonen T, et al. Immunogenicity and Reactogenicity of Co-administration of COVID-19 and Influenza Vaccines. JAMA Netw Open. 2023;6(9):e2332813. doi:10.1001/jamanetworkopen.2023.32813