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Vaccine
. 2024 May 3:S0264-410X(24)00478-X.
doi: 10.1016/j.vaccine.2024.04.051. Online ahead of print. Assessment of potential adverse events following the 2022-2023 seasonal influenza vaccines among U.S. adults aged 65 years and older
Xiangyu Chianti Shi 1 , Joann F Gruber 2 , Michelle Ondari 3 , Patricia C Lloyd 4 , Pablo Freyria Duenas 5 , Tainya C Clarke 6 , Gita Nadimpalli 7 , Sylvia Cho 8 , Laurie Feinberg 9 , Mao Hu 10 , Yoganand Chillarige 11 , Jeffrey A Kelman 12 , Richard A Forshee 13 , Steven A Anderson 14 , Azadeh Shoaibi 15
Affiliations
Background: While safety of influenza vaccines is well-established, some studies have suggested potential associations between influenza vaccines and certain adverse events (AEs). This study examined the safety of the 2022-2023 influenza vaccines among U.S. adults ≥ 65 years.
Methods: A self-controlled case series compared incidence rates of anaphylaxis, encephalitis/encephalomyelitis, Guillain-Barré Syndrome (GBS), and transverse myelitis following 2022-2023 seasonal influenza vaccinations (i.e., any, high-dose or adjuvanted) in risk and control intervals among Medicare beneficiaries ≥ 65 years. We used conditional Poisson regression to estimate incidence rate ratios (IRRs) and 95 % confidence intervals (CIs) adjusted for event-dependent observation time and seasonality. Analyses also accounted for uncertainty from outcome misclassification where feasible. For AEs with any statistically significant associations, we stratified results by concomitant vaccination status.
Results: Among 12.7 million vaccine recipients, we observed 76 anaphylaxis, 276 encephalitis/encephalomyelitis, 134 GBS and 75 transverse myelitis cases. Only rates of anaphylaxis were elevated in risk compared to control intervals. With all adjustments, an elevated, but non-statistically significant, anaphylaxis rate was observed following any (IRR: 2.40, 95% CI: 0.96-6.03), high-dose (IRR: 2.31, 95% CI: 0.67-7.91), and adjuvanted (IRR: 3.28, 95% CI: 0.71-15.08) influenza vaccination; anaphylaxis IRRs were 2.54 (95% CI: 0.49-13.05) and 1.64 (95% CI: 0.38-7.05) for persons with and without concomitant vaccination, respectively.
Conclusions: Rates of encephalitis/encephalomyelitis, GBS, or transverse myelitis were not elevated following 2022-2023 seasonal influenza vaccinations among U.S. adults ≥ 65 years. There was an increased rate of anaphylaxis following influenza vaccination that may have been influenced by concomitant vaccination.
Keywords: Adverse events; Anaphylaxis; Concomitant vaccination; Influenza vaccine; Vaccine safety.
. 2024 May 3:S0264-410X(24)00478-X.
doi: 10.1016/j.vaccine.2024.04.051. Online ahead of print. Assessment of potential adverse events following the 2022-2023 seasonal influenza vaccines among U.S. adults aged 65 years and older
Xiangyu Chianti Shi 1 , Joann F Gruber 2 , Michelle Ondari 3 , Patricia C Lloyd 4 , Pablo Freyria Duenas 5 , Tainya C Clarke 6 , Gita Nadimpalli 7 , Sylvia Cho 8 , Laurie Feinberg 9 , Mao Hu 10 , Yoganand Chillarige 11 , Jeffrey A Kelman 12 , Richard A Forshee 13 , Steven A Anderson 14 , Azadeh Shoaibi 15
Affiliations
- PMID: 38704258
- DOI: 10.1016/j.vaccine.2024.04.051
Background: While safety of influenza vaccines is well-established, some studies have suggested potential associations between influenza vaccines and certain adverse events (AEs). This study examined the safety of the 2022-2023 influenza vaccines among U.S. adults ≥ 65 years.
Methods: A self-controlled case series compared incidence rates of anaphylaxis, encephalitis/encephalomyelitis, Guillain-Barré Syndrome (GBS), and transverse myelitis following 2022-2023 seasonal influenza vaccinations (i.e., any, high-dose or adjuvanted) in risk and control intervals among Medicare beneficiaries ≥ 65 years. We used conditional Poisson regression to estimate incidence rate ratios (IRRs) and 95 % confidence intervals (CIs) adjusted for event-dependent observation time and seasonality. Analyses also accounted for uncertainty from outcome misclassification where feasible. For AEs with any statistically significant associations, we stratified results by concomitant vaccination status.
Results: Among 12.7 million vaccine recipients, we observed 76 anaphylaxis, 276 encephalitis/encephalomyelitis, 134 GBS and 75 transverse myelitis cases. Only rates of anaphylaxis were elevated in risk compared to control intervals. With all adjustments, an elevated, but non-statistically significant, anaphylaxis rate was observed following any (IRR: 2.40, 95% CI: 0.96-6.03), high-dose (IRR: 2.31, 95% CI: 0.67-7.91), and adjuvanted (IRR: 3.28, 95% CI: 0.71-15.08) influenza vaccination; anaphylaxis IRRs were 2.54 (95% CI: 0.49-13.05) and 1.64 (95% CI: 0.38-7.05) for persons with and without concomitant vaccination, respectively.
Conclusions: Rates of encephalitis/encephalomyelitis, GBS, or transverse myelitis were not elevated following 2022-2023 seasonal influenza vaccinations among U.S. adults ≥ 65 years. There was an increased rate of anaphylaxis following influenza vaccination that may have been influenced by concomitant vaccination.
Keywords: Adverse events; Anaphylaxis; Concomitant vaccination; Influenza vaccine; Vaccine safety.