Expert Q&A: Geisinger Investigator Discusses Low Flu Vaccination Rates, ICU Findings in Older Adults

At IDWeek 2026 in Washington, DC, investigators from Geisinger Health System presented a retrospective cohort study on influenza vaccination and illness severity among older adults who came to the emergency department (ED) with influenza. The study included adults aged 65 years or older with RT-PCR–confirmed influenza who presented to Geisinger EDs between October 1, 2024, and April 30, 2025. Individuals were counted as vaccinated if they had received a seasonal vaccine at least 14 days before presentation, as documented in the electronic health record or immunization registry. Of 452 patients, 80 (17.7%) were vaccinated, and the 2 groups had similar baseline characteristics. The median age was 80 years among vaccinated patients and 78 years among unvaccinated patients.¹

ICU admission occurred in 2.5% of vaccinated patients compared with 10.5% of unvaccinated patients (P = .029). Vaccinated patients also had shorter mean hospital stays (4.43 vs 5.20 days) and ICU stays (0.67 vs 3.24 days), although neither difference reached statistical significance. Hospital admission, oxygen use, and antiviral prescribing were similar between groups. The analyses were unadjusted. The investigators said they plan to conduct propensity score matching, analyze multiple seasons, and evaluate targeted electronic health record vaccination reminders. They added that rural access and insurance-related barriers warrant further study because Geisinger serves a largely rural, older population.¹

In a written Q&A with Pharmacy Times, Manouj Kumar, MD, infectious disease internist practicing in Danville, Pennsylvania, affiliated with Geisinger, discussed the barriers that may underlie the cohort’s low documented vaccination rate. These include transportation difficulties, limited access to health care, vaccine hesitancy, and missed opportunities during routine visits. Kumar described how pharmacists could help through convenient vaccine access, patient education, and reminders. Kumar also addressed how to interpret the lower ICU admission rate when other markers of severity were similar between groups. Kumar cautioned that the observational design cannot establish causality and that the small number of ICU admissions among vaccinated patients limits the precision of the finding.

Pharmacy Times: What barriers may contribute to low documented influenza vaccination rates, and what role could pharmacists play?

Manouj Kumar, MD: In our cohort, only 17.7% of patients had documented influenza vaccination. However, because this was a retrospective study, we did not directly assess the reasons for low documented vaccination or determine whether some vaccinations received outside our health system were missed.

Potential barriers in rural communities may include transportation difficulties, limited access to healthcare services, vaccine hesitancy, and missed opportunities for vaccination during routine healthcare visits. Pharmacists could help address these barriers by providing convenient vaccination access, patient education, reminders, and recommendations tailored to individual concerns. Collaboration between pharmacists and other healthcare professionals may also help improve vaccination uptake and documentation.

Pharmacy Times: How do you interpret the lower ICU admission rate despite similar hospital admission, oxygen use, and antiviral prescribing?

Kumar: In our study, ICU admission occurred in 2.5% of vaccinated patients compared with 10.5% of unvaccinated patients. In contrast, hospital admission, oxygen use, and antiviral prescribing were similar between the groups.

One possible interpretation is that vaccination may help reduce the severity of influenza in some older adults without necessarily preventing hospitalization or the need for supplemental oxygen. However, our observational study cannot establish causality, and the small number of ICU admissions among vaccinated patients limits the precision of this finding. Differences in patient characteristics, underlying health conditions, and other potential confounders may also have influenced the results.

These findings support the importance of influenza vaccination in older adults while highlighting the need for larger studies to better understand its association with severe outcomes.

REFERENCE

Ferruggia K. Flu Vaccination Linked to Fewer Severe Outcomes in Older Adults, Fewer ED Visits in Children. Pharmacy Times. October 23, 2026. Accessed October 29, 2026. https://www.pharmacytimes.com/view/flu-vaccination-linked-to-fewer-severe-outcomes-in-older-adults-fewer-ed-visits-in-children