Skip main navigation

Military Health System

Clear Your Browser Cache

This website has recently undergone changes. Users finding unexpected concerns may care to clear their browser's cache to ensure a seamless experience.

2023-2024 Mid-Season Influenza Vaccine Effectiveness Against Laboratory-Confirmed Influenza Hospitalizations: U.S. Active Component Service Members

Image of 48088663. This report provides data supporting use of influenza vaccines among typically healthy service members to prevent influenza hospitalization.

This Surveillance Snapshot provides an overview of the 2023-2024 mid-season analysis of influenza VE against influenza hospitalizations among ACSMs. Data from the DMSS and standardized laboratory data provided by DCPH–Portsmouth were utilized for this analysis.1 A cohort study design was implemented among the population of ACSMs in service at any time between September 1, 2023 and February 14, 2024. 

The outcome was defined as a laboratory-confirmed influenza-positive result (rapid antigen, RT-PCR, or culture influenza assay) with an indication that the individual was hospitalized, or a hospitalization record with the first or second diagnostic International Classification of Diseases, 10th revision code for influenza (J09-J11). Person-time started at the beginning of the surveillance period or entry into active component service (whichever came last) and was censored at either the occurrence of the outcome, end of the surveillance period, or leaving active component or military service (whichever came first). Person-time and outcomes were stratified by vaccination status. Person-time and outcomes occurring prior to vaccination and up to 13 days post-vaccination were defined as unvaccinated. Person-time and outcomes occurring at least 14 days after vaccination were defined as vaccinated. Analyses were conducted for laboratory-confirmed influenza hospitalizations alone and then combined with hospitalization records for influenza. Incidence rates per 100,000 person-years (p-yrs) were calculated and a Poisson regression model was used to calculate adjusted incidence rate ratios (adjusted for sex, age category, prior vaccination [any influenza vaccine within previous five years], and month of diagnosis) and 95% CIs. VE was defined as (1 - OR) x 100. 

There were 47 laboratory-confirmed influenza hospitalizations among ACSMs during the study period. An additional 17 influenza hospitalization records were identified using the encounter data. For both outcomes, the incidence rate of influenza hospitalization among unvaccinated ACSMs was twice the rate of vaccinated ACSMs (lab-confirmed only: 1.0 vs. 0.5 per 100,000 p-yrs; lab-confirmed and hospitalization records: 1.4 vs. 0.7 per 100,000 p-yrs) (Table). Likewise, the adjusted analysis resulted in VE estimates of 46% (95% CI: 2, 70) and 54% (95% CI: 12, 72) for the laboratory-confirmed only and laboratory-confirmed with hospitalization records, respectively. 

Click on the table to access a 508-compliant PDF version

The results of this analysis show moderate protection against hospitalization for influenza among ACSMs from the 2023-2024 seasonal influenza vaccines. Although the number of outcomes are small, the analysis still reached statistical significance and provides data supporting the use of influenza vaccines among typically healthy ACSMs to prevent influenza hospitalizations. 

Reference

  1. Rubertone MV, Brundage JF. The Defense Medical Surveillance System and the Department of Defense serum repository: glimpses of the future of public health surveillance. Am J Public Health. 2002;92(12):1900-1904. doi:10.2105/ajph.92.12.1900

You also may be interested in...

Article
Jan 1, 2024

Reportable Medical Events at Military Health System Facilities Through Week 48, Ending November 30, 2023

Each month the MSMR publishes an update of reportable medical events documented in the Disease Reporting System internet by health care providers and public health officials throughout the Military Health System, for monitoring, controlling, and preventing the occurrence and spread of diseases of public health interest or readiness importance.

Article
Jan 1, 2024

Brief Report: The Four Most Frequently Diagnosed Vector-borne Diseases Among Service Member and Non-Service Member Beneficiaries in the Geographic Combatant Commands, 2010–2022

This report provides linear trends of selected vector-borne diseases, over a 13-year surveillance period, among Armed Forces service and non-service member beneficiaries diagnosed at installations within the Northern Command (NORTHCOM), Africa Command (AFRICOM), Central Command (CENTCOM), European Command (EUCOM), Indo-Pacific Command (INDOPACOM), or ...

Article
Dec 1, 2023

Reportable Medical Events at Military Health System Facilities Through Week 44, Ending November 4, 2023

Chlamydia, by far the most frequently reported medical event (RME) with the MHS, declined by 17% in October, to 1,190 cases, from 1,437 cases (adjusted) in September; this follows a 15% decline from August to September. Gonorrhea, the second highest RME, declined 15% in October, to 192 cases reported cases in September, from 225 cases (adjusted). ...

Skip subpage navigation
Refine your search
Last Updated: May 07, 2024
Follow us on Instagram Follow us on LinkedIn Follow us on Facebook Follow us on X Follow us on YouTube Sign up on GovDelivery