Flu Vaccination Linked to Fewer Severe Outcomes in Older Adults, Fewer ED Visits in Children

• Hospital admission: 95.0% vs 96.2%;
• Oxygen use: 75.0% in both groups;
• Antibiotic prescribing: 47.5% vs 45.2%; and
• Antiviral prescribing: 90.0% vs 87.4%.

The investigators noted that only 17.7% of the cohort had documented vaccination. They said rural access and insurance-related barriers warrant further study. The analyses were unadjusted. Planned next steps include propensity score matching, analyses across multiple seasons, and evaluation of targeted electronic health record vaccination reminders.¹

Pediatric Vaccine Effectiveness in the 2025-2026 Season

During the 2025-2026 US influenza season, drifted influenza A (H3N2) subclade K viruses predominated, and influenza activity among children was high. To estimate vaccine effectiveness (VE) in this season, investigators led by Katherine Adams, DrPH, MPH, of the CDC’s National Center for Immunization and Respiratory Diseases, used a test-negative design. The study included children and adolescents aged 6 months to 17 years with ED or UC encounters for acute respiratory illness and molecular influenza testing at 6 VISION sites between October 1, 2025, and April 30, 2026. Models were adjusted for age, sex, race and ethnicity, calendar day, and site.²

Of 76,815 encounters, 25,496 were influenza cases and 51,319 were controls. Of the cases, 22% were vaccinated, compared with 29% of controls. Key adjusted VE estimates were as follows:²

• Overall: 36% (95% CI, 33%-39%);
• Influenza A: 38% (95% CI, 35%-41%);
• Influenza B: 31% (95% CI, 27%-36%);
• Aged 6 months to 4 years: 47% (95% CI, 42%-51%);
• Aged 5 to 17 years: 29% (95% CI, 25%-33%);
• ED encounters: 41% (95% CI, 38%-45%); and
• UC encounters: 28% (95% CI, 24%-33%).

VE was 40% at 14 to 59 days after vaccination, 37% at 60 to 119 days, and 34% at 120 days or more.²

Moderate Effectiveness, Meaningful Impact

The VISION investigators concluded that even moderate VE can substantially reduce the influenza burden among children and adolescents. The highest protection was seen in children aged younger than 5. The Geisinger investigators said continued vaccination outreach and adjusted analyses will help translate their findings into clinical practice.¹

The VISION authors noted that their findings do not necessarily represent the official position of the CDC.²

REFERENCES

1. Kumar M, Tice AM, Law JM, Kwon T, Wolk DM. Effectiveness of seasonal influenza vaccination in reducing severe outcomes among older adults presenting to the emergency department: a retrospective cohort study. Poster presented at: IDWeek 2026; October 21-October 24; Washington D.C. Submission ID 2416323.

2. Adams K, Reeves EL, Weber ZA, et al. Effectiveness of 2025–2026 seasonal influenza vaccines against US pediatric influenza-associated emergency department and urgent care encounters—VISION Network, October 1, 2025–April 30, 2026. Poster presented at: IDWeek 2026; October 21-October 24; Washington D.C.

3. Grohskopf LA, Ferdinands JM, Blanton LH, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices—United States, 2024–25 influenza season. MMWR Recomm Rep. 2024;73(RR-5):1-25. doi:10.15585/mmwr.rr7305a1