October 11, 2018
2 min read

Adjuvanted flu vaccine may reduce hospitalization risk in nursing home residents

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Stefan Gravenstein, MD, MPH
Stefan Gravenstein

SAN FRANCISCO — Giving long-stay nursing home residents an adjuvanted trivalent influenza vaccine may reduce their risk for hospitalization compared with a non-adjuvanted trivalent influenza vaccine, according to study findings presented at IDWeek.

Stefan Gravenstein , MD, MPH, professor of medicine and health services, policy and practice at the Brown University School of Public Health, and colleagues noted that pneumonia and influenza are the leading vaccine-preventable infections in nursing homes and said more immunogenic vaccines, such as the adjuvanted trivalent influenza vaccine (aTIV), can improve clinical outcomes in nursing home patients.

“Vaccine efficacy to all vaccines declines with age,” Gravenstein told Infectious Disease News. “So, the lingering question is, Is increased immunogenicity sufficient to reduce clinical impact even in the oldest, frailest adults? That question is germane especially for the adjuvanted flu vaccine, which lacks randomized control trial evidence for better clinical outcomes in older adults, although it’s licensed specifically for this age group.”

To determine whether aTIV or the standard seasonal trivalent influenza vaccine (TIV) is more effective for nursing home residents, Gravenstein and colleagues randomly assigned 823 nursing homes within 75 miles of a CDC influenza reporting city to offer either aTIV or TIV as their standard vaccine for the 2016-2017 influenza season. They built a subset of patients aged 65 years or older who stayed in a nursing home for more than 100 days as of Oct. 1, 2016, and determined how many were hospitalized from Nov. 1, 2016 to June 1, 2017, and why. The primary outcome was time to first hospitalization.

According to the study, the sample of patients included 26,300 residents in 412 nursing homes assigned to offer aTIV and 26,474 residents in 410 nursing homes that offered TIV. The number of residents vaccinated was 17,976 and 18,364, respectively.

According to study findings, there were 5,479 (20.8%) hospitalizations in the aTIV nursing homes and 5,839 (22.1%) in the TIV nursing homes (HR = 0.94; 95% CI, 0.88-0.99). In the aTIV nursing homes, 18.2% of residents died compared with 17.5% of residents in the TIV nursing homes (HR = 1.05; 95% CI, 0.99-1.11).

Gravenstein and colleagues said aTIV may reduce hospitalization risk for long-term nursing home residents during a predominantly influenza A/H3N2 season, despite reported reduced effectiveness due to egg-based vaccine mutations.

“There still exists ample skepticism of the value of influenza vaccine to older adults [and] there is only slowly growing recognition of the influenza vaccine’s benefit beyond just reducing clinically recognizable influenza cases,” Gravenstein said. “[Our] study demonstrates vaccine benefit [using] an easy metric — hospitalized or not — that is clinically important, expensive and debilitating, albeit a single-season outcome. Once again, another more immunogenic vaccine offers clinical benefit despite advanced age and frailty — in this case, in the context of an influenza vaccine, egg-based mutagenesis and an A/H3N2-predominant influenza season.” – by Caitlyn Stulpin

Reference: Gravenstein S, et al. Abstract 996. Presented at: ID Week; Oct. 3-7, 2018; San Francisco.

Disclosures: Gravenstein reports being a consultant, grant investigator and scientific advisor for Seqirus. Please see the abstract for all other authors’ relevant financial disclosures.