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.

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

Image of 48088663. This report provides an overview of the 2023-2024 mid-season analysis of influenza vaccine effectiveness against medically-attended ambulatory influenza infections.

This Surveillance Snapshot provides an overview of the 2023-2024 mid-season analysis of influenza VE against medically-attended ambulatory influenza infections among active component service members. Data from the Defense Medical Surveillance System, the NHRC’s respiratory surveillance program, and standardized laboratory data provided by the Defense Centers for Public Health–Portsmouth were used for this analysis.1,2 A case test-negative study design was implemented among the population of ACSMs from all services who were tested for influenza between December 1, 2023 and February 23, 2024—the period of peak influenza activity for the season. 

Cases were defined as individuals with a positive influenza result from a rapid antigen, reverse transcription polymerase chain reaction or culture influenza assay. Test-negative controls were individuals with a negative influenza result from a RT-PCR or culture influenza assay. Crude odds ratios were calculated and multivariate logistic regression was used to calculate adjusted ORs (adjusted for sex, age category, prior vaccination [any influenza vaccine in previous 5 years], and month of diagnosis) and 95% confidence intervals. VE estimates were defined as (1 - OR) x 100. 

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

There were 3,540 cases—2,794 A (any subtype), 246 A(H3N2), 119 A(H1N1)pdm09, 751 B (any type)—and 16,411 TNCs. TNCs were more likely vaccinated (85.4%) than cases (82.5%). VE varied by influenza type (Table). Statistically significant VE was found against any influenza case with an adjusted VE of 21% (95% CI: 13, 29) and influenza A (any subtype) with an adjusted VE of 26% (95% CI: 18, 34). The VE point estimate against influenza A(H1N1)pdm09 and A(H3N2) showed effectiveness, but did not reach statistical significance (23% [95% CI: -23, 51] and 28% [95% CI: -1, 49], respectively). This mid-season assessment did not find the vaccine to be effective against influenza B ambulatory infections (-5% [95% CI: -30, 15]). 

The results of this analysis show low protection of the 2023-2024 seasonal influenza vaccines against medically-attended influenza A infections that resulted in ambulatory care visits among ACSMs. As these estimates were obtained during the middle of the influenza season, VE estimates and CIs may change when data from the full season are available and sample sizes increase. 

References

  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 
  2. https://www.med.navy.mil/Naval-Medical-Research-Command/R-D-Commands/Naval-Health-Research-Center/Core-Research/Operational-Infectious Diseases/respiratory-surveillance-2023-2024

You also may be interested in...

Report
Oct 1, 2023

MSMR Vol. 30 No. 10 - October 2023

.PDF | 1.29 MB

The October 2023 Medical Surveillance Monthly Report (MSMR) provides a review of the incidence of colorectal cancer among active component service members from 2010 to 2022; followed by a study of force protection risks in AFRICOM, INDOPACOM, and SOUTHCOM due to rapid diagnostic test failures for P. falciparum malaria from 2016 to 2022; then an update ...

Article
Sep 1, 2023

Update: Routine Screening for Antibodies to Human Immunodeficiency Virus, U.S. Armed Forces, Active and Reserve Components, January 2018–June 2023

This report provides an update through June 2023 of routine screening results for antibodies to HIV among members of the U.S. military. From January 2018 through June 2023, approximately 7 million U.S. military service members (active component, reserve component, and national guard) were tested for HIV antibodies; 1,502 were identified as HIV ...

Report
Sep 1, 2023

MSMR Vol. 30 No. 9 - September 2023

.PDF | 1.30 MB

The September 2023 MSMR provides the annual update of routine screening for antibodies to HIV among the active and reserve components of the U.S. Armed Forces; followed by a serological survey of Ross River virus (RRV) infection among U.S. Marine expeditionary forces who train in Australia; followed by a Surveillance Snapshot of the 10 leading ...

Article
Aug 1, 2023

Active Surveillance for Acute Respiratory Disease Detected No Outbreaks at Four U.S. Army Basic Training Installations in 2022

This article presents the 2022 results of the active surveillance program for acute respiratory disease and Group A Beta-Hemolytic Streptococcus conducted by the Defense Centers for Public Health-Aberdeen at the four Army installations responsible for basic combat training or one-station unit training. This ARD surveillance program rapidly monitors, ...

Article
Aug 1, 2023

Case Report: Complicated Urinary Tract Infection Due to an Extensively Resistant Escherichia coli in a Returning Traveler

This article presents the medical case report of a 76-year-old man who returned to the U.S. following overseas travel and was admitted at Hawai'i's Tri­pler Army Medical Center with a complicated urinary tract infection due to an extensively resistant strain of E. coli.

Report
Aug 1, 2023

MSMR Vol. 30 No. 8 - August 2023

.PDF | 1.02 MB

The August 2023 MSMR provides the most recent data from the active surveillance program for acute respiratory disease and Group A Beta-Hemolytic Streptococcus among U.S. Army basic trainees; then summarizes the case report of an extensively resistant E. coli in a returning traveler at Hawai'i's Tripler Army Medical Center; followed by a Surveillance ...

Article
Jul 1, 2023

Absolute and Relative Morbidity Burdens Attributable to Various Illnesses and Injuries Among Non-Service Member Beneficiaries of the Military Health System, 2022

This report represents an updated summary of care provided to non-service members in the MHS during calendar year 2022. MHS beneficiaries are diverse and heterogeneous, including active component service members, activated National Guard and Reserve service members, active component immediate family, retirees, and their family members, with differing ...

Article
Jul 1, 2023

Morbidity Burdens Attributable to Various Illnesses and Injuries Among Deployed Active and Reserve Component Service Members, U.S. Armed Forces, 2022

This annual estimate of illness- and injury-related morbidity and health care burdens on the U.S. Armed Forces and MHS updates previous analyses of these burden distributions among active and reserve component service members in deployed settings. This report focuses on the health encounters of service members during deployment to U.S. Central Command ...

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