Efficacy of High- vs. Standard-Dose Flu Vaccine Compared in Older Adults

A review of randomized studies was conducted analyzing the effectiveness of IIV3-HD in adults aged ≥65 years
A review of randomized studies was conducted analyzing the effectiveness of IIV3-HD in adults aged ≥65 years

This article is written live from ID Week 2017 Annual Meeting in San Diego, CA. MPR will be reporting news on the latest findings from leading experts in infectious diseases. Check back for more news from IDWeek 2017.


SAN DIEGO—Findings from a systematic review and meta-analysis presented at IDWeek 2017 showed that Fluzone High-Dose (IIV3-HD) was more effective than standard-dose influenza vaccine (IIV3-SD) at lowering clinical outcomes associated with influenza infection in older adults. 

For adults aged ≥65 years, seasonal flu epidemics pose significant disease burden annually and not many vaccines are specifically formulated for this patient population. Study author, Jason Lee, MSc, MBiotech, from University of Toronto, and colleague aimed to analyze efficacy and effectiveness data of Fluzone High-Dose (intended for adults aged ≥65 years) vs. IIV3-SD against clinical outcomes (eg, influenza-like illness, hospitalization, death) known to be related to influenza infection. 

Study authors conducted a systematic review of randomized and observational studies evaluating vaccine efficacy or effectiveness of IIV3-HD for clinical outcomes in adults aged ≥65 years. A meta-analysis was also conducted based on individual vaccine efficacy or effectiveness reported in the studies. A total of 4 randomized trials and 3 observational studies were identified for analysis. Of these, 5 evaluated relative vaccine efficacy or effectiveness(rVE) for IIV3-HD vs. IIV3-SD against influenza-like illness, 6 reported on hospital admissions, and 3 on death. 

The pooled data showed IIV3-HD exhibited greater protection against influenza-like illness (rVE 18.3%, 95% CI: 7.0, 28.3%; P=0.002) and more effectively prevented hospital admissions due to influenza illness (rVE 19.4%; P<0.001), pneumonia (rVE 25.1%; P=0.001), cardiorespiratory events (rVE 18.2%; P=0.002), all-cause hospital admission (rVE 8.8%; P=0.025), and death after a hospital admission for influenza (rVE 22.2%; P=0.240). 

IIV3-SD showed a "modest but not statistically significant impact" on all-cause hospitalization (rVE 7.3%, 95% CI: -1.5 to 15.4%) and all-cause mortality (rVE 0.8%, 95% CI: -4.2 to 5.5%). 

Reference:

Lee, J. Efficacy and Effectiveness of High-Dose Influenza Vaccine for Older Adults: A Systematic Review and Meta-analysis. Poster presented at IDWeek; October 4–8, 2017; San Diego, CA. http://www.idweek.org