Giuseppe
Emeritus
ECDC Health Content: Influenza vaccination in the elderly: current evidence and uncertainties.
Influenza vaccination in the elderly: current evidence and uncertainties
Author:
Knottnerus, J. A. "Influenza vaccination in the elderly: current evidence and uncertainties." Journal of Clinical Epidemiology In Press, Corrected Proof.
Description and ECDC Comment:
The commentary by a member of the Health Council of the Netherlands summarises much of the available trial and observational evidence that relate to the the effectiveness of influenza vaccination in the elderly, informing future studies in the topic. Few randomized controlled trials of the efficacy of influenza immunization in older adults have been carried out therefore much of the available evidence comes from observational studies. The authors highlight the trial carried out by Govaert et al., a population-based trial among the elderly (60 years old and above) ? both high-risk and healthy patients ? that found that influenza vaccination was effective in preventing serologically confirmed influenza, given a good match between the vaccine and the circulating virus strains.(1)
The author also mentions the mortality follow-up to this trial.(2)
The author notes the decline of influenza vaccine effectiveness with age is modest as to laboratory confirmed influenza, differs by strain and can be counteracted by re-vaccination. Season incidences and matches between vaccine and circulating virus strains will vary over the years but, nevertheless, the author argues that influenza vaccination is a helpful public health measure in preventing influenza in the elderly.
As to whether influenza vaccination in the elderly is also effective in preventing severe morbidity complications and mortality, the only relevant randomized trial is that by Thijs The author points out that since influenza vaccination is considered protective in older people most authorities would consider a classical placebo-controlled randomized trial for this purpose to be unethical as well as impractical because of the numbers involved.
Authorities are going to have to rely on observational data and stating that more trial data are needed will lead to a situation of no decision on policy.
The author considers the available facts on the topic of elderly influenza vaccination: the available experimental evidence, the plausibility of these outcomes when it comes to elucidate predictive risk factors for severe complications and mortality and possible ways of reducing bias from observational studies.
In the meantime, and whilst waiting for more observational studies able to provide such evidence, the author argues that decisions to offer vaccination to high-risk groups and the elderly cannot is a reasonable and safe policy.
1. Govaert TM, Thijs CT, Masurel N, Sprenger MJ, Dinant GJ, Knottnerus JA. The efficacy of influenza vaccination in elderly individuals. A randomized double-blind placebo-controlled trial. JAMA 1994;272:1661-5.
2. Thijs C, Beyer WE, Govaert PM, Sprenger MJ, Dinant GJ, Knottnerus A. Mortality benefits of influenza vaccination in elderly people. Lancet Infect Dis. 2008;8:460-1
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<cite cite="http://ecdc.europa.eu/en/health_content/sciadv/090423_sciadv.aspx">ECDC Health Content</cite>Author:
Knottnerus, J. A. "Influenza vaccination in the elderly: current evidence and uncertainties." Journal of Clinical Epidemiology In Press, Corrected Proof.
Description and ECDC Comment:
The commentary by a member of the Health Council of the Netherlands summarises much of the available trial and observational evidence that relate to the the effectiveness of influenza vaccination in the elderly, informing future studies in the topic. Few randomized controlled trials of the efficacy of influenza immunization in older adults have been carried out therefore much of the available evidence comes from observational studies. The authors highlight the trial carried out by Govaert et al., a population-based trial among the elderly (60 years old and above) ? both high-risk and healthy patients ? that found that influenza vaccination was effective in preventing serologically confirmed influenza, given a good match between the vaccine and the circulating virus strains.(1)
The author also mentions the mortality follow-up to this trial.(2)
The author notes the decline of influenza vaccine effectiveness with age is modest as to laboratory confirmed influenza, differs by strain and can be counteracted by re-vaccination. Season incidences and matches between vaccine and circulating virus strains will vary over the years but, nevertheless, the author argues that influenza vaccination is a helpful public health measure in preventing influenza in the elderly.
As to whether influenza vaccination in the elderly is also effective in preventing severe morbidity complications and mortality, the only relevant randomized trial is that by Thijs The author points out that since influenza vaccination is considered protective in older people most authorities would consider a classical placebo-controlled randomized trial for this purpose to be unethical as well as impractical because of the numbers involved.
Authorities are going to have to rely on observational data and stating that more trial data are needed will lead to a situation of no decision on policy.
The author considers the available facts on the topic of elderly influenza vaccination: the available experimental evidence, the plausibility of these outcomes when it comes to elucidate predictive risk factors for severe complications and mortality and possible ways of reducing bias from observational studies.
In the meantime, and whilst waiting for more observational studies able to provide such evidence, the author argues that decisions to offer vaccination to high-risk groups and the elderly cannot is a reasonable and safe policy.
1. Govaert TM, Thijs CT, Masurel N, Sprenger MJ, Dinant GJ, Knottnerus JA. The efficacy of influenza vaccination in elderly individuals. A randomized double-blind placebo-controlled trial. JAMA 1994;272:1661-5.
2. Thijs C, Beyer WE, Govaert PM, Sprenger MJ, Dinant GJ, Knottnerus A. Mortality benefits of influenza vaccination in elderly people. Lancet Infect Dis. 2008;8:460-1
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