Seasonal Influenza Vaccine Effectiveness Lower for Immunocompromised Adults

Vaccine effectiveness (VE) for the seasonal influenza vaccine is lower but not significantly different between adult outpatients with vs without immunocompromised conditions, according to study results presented at IDWeek 2023, held from October 11 to 15, in Boston, Massachusetts.

The higher risk for severe influenza infection in immunocompromised individuals highlights the need for ongoing evaluation into the VE of seasonal influenza vaccines among this population.

Researchers conducted a study to assess the VE of the 2017 to 2018 seasonal influenza vaccine against symptomatic influenza among immunocompromised outpatients. Data for the analysis were sourced from the US Flu VE Network, and eligible patients were enrolled in 5 states and had their immunocompromised status confirmed via diagnostic codes.

Logistic regression was used to assess influenza VE, with adjustments for enrollment site, race, self-reported general health status, age, and date of symptom onset. The researchers constructed separate models to compare influenza VE between adult outpatients with vs without immunocompromised conditions.

A total of 5671 adult outpatients were identified for the analysis, of whom 455 (8%) were immunocompromised.

In the adjusted analysis, the VE of the 2017 to 2018 seasonal influenza vaccine was -4% (95% CI, -66 to 35) among adults with immunocompromised conditions and 31% (95% CI, 22-39) among those without immunocompromised conditions. Although VE was lower for immunocompromised patients, the between-group difference was not significant (P =.100).

According to the researchers, “This study demonstrates the capacity to study a large IC [immunocompromised] population using an existing influenza VE network and contributes to the literature to support large, multicenter VE studies for IC populations.” 

This article originally appeared on Infectious Disease Advisor.