Simultaneous Administration of COVID-19 Booster, Influenza Vaccine May Increase Likelihood of System Reaction

Individuals vaccinated simultaneously with COVID-19 booster and influenza vaccines may be more likely to experience systemic reactions and adverse health impacts.

Simultaneous administration of COVID-19 mRNA booster vaccines and seasonal influenza vaccines may be associated with increased likelihood of systemic reactions during the week following vaccination, according to a study recently published in JAMA Network Open.

Participants who received Moderna COVID-19 booster and influenza vaccines simultaneously were also slightly more likely to report adverse health impacts than participants who received a COVID-19 booster vaccination alone.

“Authorization of COVID-19 vaccine booster doses coincided with the recommended period for seasonal influenza vaccination, increasing the likelihood of simultaneous administration of COVID-19 and influenza vaccine,” wrote the authors. “Simultaneous administration of vaccines is efficient and may improve coverage with each vaccine. However, the safety of simultaneous administration of COVID-19 and influenza vaccines has not been well described.”

Researchers conducted a retrospective cohort study to evaluate adverse events and health impacts associated with simultaneous administration of COVID-19 mRNA boosters and seasonal influenza vaccines among individuals in the United States.

Participants had voluntarily registered in V-safe, a voluntary smartphone-based monitoring system established by the CDC, following COVID-19 vaccination. Vaccine data were self-reported by participants through V-safe on days 0 through 7 after vaccination between September 22, 2021, and May 1, 2022.

Researchers analyzed reports of local injection site and systemic reactions as well as health impacts reported by participants.

A total of 981,099 individuals aged 12 or older registered with V-safe. Of these registrants, 92,023 reported receiving simultaneous administration of COVID-19 mRNA booster and seasonal influenza vaccines.

In the week following vaccination, systemic reactions were reported by more than half (58.9%) of the 61,390 respondents who simultaneously received Pfizer-BioNTech COVID-19 booster and influenza vaccines. Systemic reactions were reported by 68.6% of 30,633 respondents who simultaneously received Moderna booster and influenza vaccines.

Among respondents who simultaneously received a Pfizer-BioNTech or Moderna COVID-19 booster and a seasonal influenza vaccine, 8% and 11%, respectively, reported systemic reactions in the week after vaccination. This was more frequent than respondents who received a COVID-19 mRNA booster vaccine alone.

However, most reactions were reported to be mild or moderate, occurring most frequently on the day after vaccination. The most frequently reported systemic reactions were fatigue, headache, and myalgia.

Researchers estimated adjusted odds ratios (aORs) for simultaneous administration compared with booster dose alone, controlling for sex, age, and week of vaccination.

Both respondents who simultaneously received influenza and Pfizer-BioNTech vaccines (aOR, 1.08; 95% CI, 1.06-1.10) and respondents who simultaneously received Moderna booster and influenza vaccines (aOR, 1.11; 95% CI, 1.08-1.14) were slightly more likely to report any systemic reaction in the week following vaccination, compared with the 889,076 respondents who received only a COVID-19 mRNA booster.

Health impacts in the week after vaccination were reported by 19% of respondents who received Pfizer-BioNTech booster and influenza vaccines simultaneously and 26.8% who received Moderna COVID-19 booster and influenza vaccines. The most commonly reported health impact was the inability to perform normal daily activities.

Hospitalization following vaccination was infrequently reported and often considered unrelated to vaccination by the respondent, according to the study.

Respondents who simultaneously received Pfizer BioNTech Booster and influenza vaccines were not more likely to report a health impact in the week following vaccination. However, respondents who received Moderna booster and influenza vaccines simultaneously were slightly more likely to report health impacts in the week following vaccination (aOR, 1.05; 95% CI, 1.02-1.08), compared with respondents who received a Moderna COVID-19 booster alone.

The authors said they hope that their findings may help better characterize outcomes associated with simultaneously administered COVID-19 mRNA booster and influenza vaccines.

Reference

Hause AM, Zhang B, Yue X, Marquez P, Myers TR, Parker C, et al. Reactogenicity of Simultaneous COVID-19 mRNA booster and Influenza Vaccination in the US. JAMA Network Open. 2022;5(7). https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2794318?utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_term=071522. Published July 15, 2022. Accessed July 18, 2022.