August 04, 2017
3 min read

High-dose influenza vaccine reduces hospitalizations among nursing home residents

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The incidence of respiratory-related hospitalizations was significantly lower in nursing home facilities that offered residents a high-dose influenza vaccine than in facilities that offered residents a standard-dose vaccine, according to recent study findings.

“Influenza is clinically the most important viral infection in older adults, annually affecting the lives of 4 million adults aged 65 years and older in the United States at a cost of $8.3 billion,” Stefan Gravenstein, MD, MPH, professor at the Warren Alpert Medical School and School of Public Health at Brown University, and colleagues wrote in Lancet Respiratory Medicine. “Data on the effect of high-dose influenza vaccines in nursing homes remain limited to a single immunogenicity study; therefore, there is a need to look at the clinical effectiveness of this vaccine in older adults living in this environment.”

Photo of Stefan Gravenstein
Stefan Gravenstein

The researchers compared the effect of the high-dose influenza vaccine (Fluzone High-Dose, Sanofi Pasteur) with the standard-dose vaccine in 38,256 participants aged 65 years or older from 823 nursing homes in the United States during the 2013-2014 influenza season. They randomly assigned 414 facilities to offer the standard-dose vaccine and 409 facilities to offer the high-dose vaccine, which has four times the antigen than the standard dose, according to the researchers.

Medicare hospital claims data showed that the incidence of respiratory-related hospitalizations over the 6 months after vaccination was 3.4% in facilities that offered the high-dose influenza vaccine vs. 3.9% in facilities that offered the standard-dose vaccine (adjusted RR = 0.873; 95% CI, 0.776-0.982). Overall, the researchers observed a 12.7% relative reduction in hospital admissions for respiratory illness among participants living in high-dose vaccine facilities (aRR = 0.83; 95% CI, 0.776-0.982).

In addition to respiratory-related hospitalizations, the high-dose vaccine was also associated with fewer all-cause hospitalizations. There were 0.067 hospitalizations per 1,000 resident-days among participants from high-dose vaccine facilities vs. 0.084 per 1,000 resident-days among those from standard-dose vaccine facilities (aRR = 0.791; 95% CI, 0.267-0.953). Furthermore, the incidence of all-cause hospital admissions was approximately 8% lower in the high-dose group (aRR = 0.915; 95% CI, 0.863-0.970). However, there was no significant difference in all-cause mortality.

Image of H1N1 influenza virus
H1N1 influenza virus. A recent randomized clinical trial showed that high-dose influenza vaccine can reduce risk for respiratory-related hospital admissions from nursing home residents aged 65 years and older.
Source: National Institute of Allergy and Infectious Diseases

In a press release, Gravenstein said the findings are particularly significant given that the predominant strain during the 2013-2014 season — A/H1N1 — is believed to be less virulent in older populations. Therefore, the study may represent a “conservative assessment of effect,” the researchers wrote.

“We’ve heard a lot about how ‘vaccines don’t work well in older people,’ and to them I say: we now have compelling evidence that there is an influenza vaccine that can prevent important clinical outcomes, even in those too frail to live on their own,” Gravenstein told Infectious Disease News. “The nursing home resident is among the groups of people least likely to gain protection from conventional influenza vaccine, and here we demonstrate that a high-dose vaccine can reduce the risk of hospitalization overall, and specifically hospitalization from respiratory illness.”

In a related editorial, Marc-Alain Widdowson, VetMB, MSc, and Joseph S. Bresee, MD, FAAP, of the division of global health protection at CDC’s Center for Global Health, warned that the reduction in all-cause hospitalizations, which was “unexpectedly high,” should be interpreted with caution because respiratory-coded hospitalizations represented only one in five of these admissions. Still, they said the results, along with findings of similar studies, indicate that the high-dose vaccine may lead to substantially greater reductions in seasonal hospital admissions among older nursing home residents compared with the standard-dose vaccine.

“With the recent [FDA] approval of adjuvanted influenza vaccine for people aged 65 years and over and a recombinant protein vaccine also licensed for this age group, the public health community has a growing range of options to better reduce the burden of influenza-associated severe disease and death in this highest risk population for the first time in more than 60 years,” they wrote. – by Stephanie Viguers

Disclosure: Gravenstein reports receiving grants and personal fees from Pfizer, Sanofi Pasteur and Seqirus, and consulting or speaker fees from Catapult Consultants, GlaxoSmithKline, Healthcentric Advisors, Janssen, Merck, Novartis, Pfizer and Longeveron. Please see the study for all other authors’ relevant financial disclosures.