Does High-Dose Flu Vaccine Reduce Hospitalizations in Nursing Home Residents?

A high-dose trivalent influenza vaccine provided better protection against respiratory and all-cause hospital admissions than a standard-dose influenza vaccine in elderly nursing home residents, according to a study published in Lancet Respiratory Medicine.¹

In the High Dose Influenza Vaccination and Morbidity & Mortality in US Nursing Homes study (ClinicalTrials.gov identifier: NCT01815268), a research team led by Stefan Gravenstein, MD, MPH, from Brown University’s Warren Alpert School of Medicine, randomly assigned 823 Medicare-certified nursing homes so that their residents aged 65 years or older would receive either the high-dose vaccine (409 facilities) or the standard-dose vaccine (414 facilities) for the 2013 to 2014 influenza season. High-dose and standard-dose vaccines were administered to 26,639 and 26,369 residents, respectively.

On analysis of Medicare fee-for-service claims, the researchers found that hospital admissions related to pulmonary and influenza-like illness in the high-dose vaccine cohort were significantly lower in the 6 months after vaccination (0.185 per 1000 resident-days, or 3.4% over 6 months, vs 0.211 per 1000 resident-days, or 3.9% over 6 months; unadjusted risk ratio, 0.888 [95% CI, 0.785-1.005; P =.061]; adjusted relative risk, 0.873 [95% CI, 0.776-0.982; P =.023]).

After adjustment for prespecified patient and facility characteristics, there was a 12.7% relative reduction in the incidence of hospital admissions in patients who received the high-dose vaccine. All-cause incidence of hospital admission was significantly lower in the high-dose cohort (1.131 per 1000 resident-days, or 20.6% over 6 months, vs 1.209 per 1000 resident-days, or 22.1% over 6 months; absolute risk reduction, 0.933; 95% CI, 0.884-0.985; P =.012). No between-group differences were found for secondary outcomes of all-cause mortality or functional decline.

In an email interview with Pulmonology Advisor, Dr Gravenstein stated that patients aged 65 years and older at highest risk for hospitalization have the most to gain from high-dose influenza vaccine, but that all patients in that age group stand to benefit. “In several countries including the US and Canada, influenza vaccine is covered by insurance, yet a third or more don’t avail themselves of this important annual benefit,”² he noted. “A good place to start would be for influenza vaccine to gain cultural acceptance as something seniors would demand rather than shrug off, whether high dose or not. And those more informed could further nuance their decision as to which vaccine is right for them.”

Some experts had previously questioned the value of influenza vaccination in elderly adults, citing a lack of evidence.³ Although prior observational studies^3,4 comparing morbidity and mortality risks in groups of vaccinated and unvaccinated older adults have been conducted, the current study was the first prospective randomized trial to directly evaluate the clinical effectiveness of licensed vaccines in a nursing home population.

“An important observation [about the study] for the many skeptics about influenza vaccine’s ability to protect seniors is that influenza vaccine can offer protection from what matters most (hospitalization), even during a mild flu season,” Dr Gravenstein noted. “Clinicians who think this reduced hospitalization risk is of value to their patients have a once-a-year opportunity to add it to their offerings.”

Disclosures: Funding for this study was provided by Sanofi Pasteur. Dr Gravenstein reports grants and personal fees from Sanofi Pasteur, Seqirus, and Pfizer, as well as consulting or speaking fees from Catapult Consultants, GlaxoSmithKline, Healthcentric Advisors, Janssen, Merck, Novartis, Pfizer, and Longeveron. Dr Davidson reports grants from Sanofi Pasteur and Seqirus. Dr Han also reports grants from Sanofi Pasteur and Seqirus. Dr Mor reports fees for chairing the independent quality committee of HCR-Manorcare, a nursing home company, and for chairing the Scientific Advisor Committee of naviHealth, a post-acute care company.

References

1. Gravenstein S, Davidson HE, Taljaard M, et al. Comparative effectiveness of high-dose versus standard-dose influenza vaccination on numbers of US nursing home residents admitted to hospital: a cluster-randomised trial [published online July 20, 2017]. Lancet Respir Med. doi:10.1016/S2213-2600(17)30235-7
2. Flu Vaccination Coverage, United States, 2014-2015 Influenza Season. Atlanta, GA: US Centers for Disease Control and Prevention. https://www.cdc.gov/flu/fluvaxview/coverage-1415estimates.htm. Updated June 23, 2016. Accessed July 31, 2017.
3. Simonsen L, Taylor RJ, Viboud C, Miller MA, Jackson LA. Mortality benefits of influenza vaccination in elderly people: an ongoing controversy. Lancet Infect Dis. 2007;7(10):658-666. doi:10.1016/S1473-3099(07)70236-0
4. Pop-Vicas A, Rahman M, Gozalo PL, Gravenstein S, Mor V. Estimating the effect of influenza vaccination on nursing home residents’ morbidity and mortality. J Am Geriatr Soc. 2015;63(9):1798-1804. doi:10.1111/jgs.13617