# 7869
A topic we’ve covered often in the past has been the limited effectiveness of influenza vaccines among the elderly (>=65) (see Flu Shots And The Elderly, NFID: The Challenges Of Influenza In Older Adults, BMC Infectious Diseases: Waning Flu Vaccine Protection In the Elderly) or those with compromised or suppressed immune systems. Those populations most endangered by influenza are, unfortunately, the least likely to be protected by the flu vaccine.
That isn’t to say the flu vaccine is worthless, or not worth bothering with.I get the flu shot every year, and I encouraged my Dad to get one until he died at the age of 87, even knowing its limitations. When dealing with a potentially life threatening illness . . . some protection beats no protection, any day of the week.
But, like seat belts, flu shots can only offer so much protection. For healthy adults under the age of 65, flu shots are generally described as being moderately effective. In October of 2011, in CIDRAP: A Comprehensive Flu Vaccine Effectiveness Meta-Analysis, we saw a major review indicating the TIV (Trivalent Influenza Vaccine) - during 8 of 12 flu seasons (67%) – produced a combined efficacy of only 59% among healthy adults (aged 18–65 years).
They found the protective effects of the flu vaccine could vary considerably from one season to the next, as well as among different age groups.
Also in 2011, NFID - the National Foundation for Infectious Diseases - convened a group of experts to address the issues of influenza and the elderly. From that panel a 5-page brief has emerged, called: Understanding the Challenges and Opportunities in Protecting Older Adults from Influenza.
Yesterday the open access journal PLoS One published a new retrospective study conducted in Ontario, Canada that attempts to quantify the level of protection those over the age of 65 received from seasonal influenza vaccination. Not surprisingly, they found that the VE (vaccine effectiveness) to be considerably lower than what has been seen with younger adults.
Research Article
Benjamin J. Ridenhour mail,Michael A. Campitelli, Jeffrey C. Kwong, Laura C. Rosella, Ben G. Armstrong, Punam Mangtani, Andrew J. Calzavara, David K. Shay
Abstract
Background
Estimates of the effectiveness of influenza vaccines in older adults may be biased because of difficulties identifying and adjusting for confounders of the vaccine-outcome association. We estimated vaccine effectiveness for prevention of serious influenza complications among older persons by using methods to account for underlying differences in risk for these complications.
Methods
We conducted a retrospective cohort study among Ontario residents aged ≥65 years from September 1993 through September 2008. We linked weekly vaccination, hospitalization, and death records for 1.4 million community-dwelling persons aged ≥65 years. Vaccine effectiveness was estimated by comparing ratios of outcome rates during weeks of high versus low influenza activity (defined by viral surveillance data) among vaccinated and unvaccinated subjects by using log-linear regression models that accounted for temperature and time trends with natural spline functions. Effectiveness was estimated for three influenza-associated outcomes: all-cause deaths, deaths occurring within 30 days of pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations.
Results
During weeks when 5% of respiratory specimens tested positive for influenza A, vaccine effectiveness among persons aged ≥65 years was 22% (95% confidence interval [CI], −6%–42%) for all influenza-associated deaths, 25% (95% CI, 13%–37%) for deaths occurring within 30 days after an influenza-associated pneumonia/influenza hospitalization, and 19% (95% CI, 4%–31%) for influenza-associated pneumonia/influenza hospitalizations. Because small proportions of deaths, deaths after pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations were associated with influenza virus circulation, we estimated that vaccination prevented 1.6%, 4.8%, and 4.1% of these outcomes, respectively.
Conclusions
By using confounding-reducing techniques with 15 years of provincial-level data including vaccination and health outcomes, we estimated that influenza vaccination prevented ~4% of influenza-associated hospitalizations and deaths occurring after hospitalizations among older adults in Ontario.
Those whose eyes don’t bleed when reading about complex statistical methods will want to peruse the entire study. In an act of self preservation, I admit I only skimmed those areas. The bottom line is that by using statistical analyses far above my pay grade, these authors have determined that the seasonal flu vaccine had about a 22% VE rating for those over the age of 65.
In an accompanying press release from the University of Notre Dame, we get the following summation.
Notre Dame researchers look at benefits of flu vaccines in the elderly
Sarah Craig
October 16, 2013
(EXCERPT)
In their central findings of the research, the authors said, “By combining health data with climate data and developing novel statistical analyses, we found that vaccination was 19 percent effective at preventing pneumonia- or influenza-related hospitalizations and 25 percent effective at preventing death occurring subsequent to a pneumonia- or influenza-related hospitalization.”
The results indicate that, over a long time period, the influenza vaccine has performed worse than expected in elderly individuals, thus proving the need for improvements in influenza vaccine development.
If that last observation sounds familiar, it is likely because it echo’s the sentiments of last year’s major report (see CIDRAP: The Need For `Game Changing’ Flu Vaccines).
The Compelling Need for Game-Changing Influenza Vaccines
An Analysis of the Influenza Vaccine Enterprise and Recommendations for the Future
Michael T. Osterholm, PhD, MPH, Nicholas S. Kelley, PhD, Jill M. Manske, PhD, MPH, Katie S. Ballering, PhD, Tabitha R. Leighton, MPH, Kristine A. Moore, MD, MPH
For those not ready to commit to reading a 160-page report, there is a 12-page Executive summary available.
While today’s study provides a disappointing result, and highlights the need for developing better influenza vaccines, the bottom line is that the current vaccine was found to be `25 percent effective at preventing death occurring subsequent to a pneumonia- or influenza-related hospitalization’.
Given the toll that influenza takes on the elderly, that 25% survival advantage has to be viewed as being better than no advantage at all.
