|
Überraschende Experten-Meinung: die positive Wirkung der Grippeschutzimpfung
wird bei der Haupt-Zielgruppe "ältere Menschen" stark
übertrieben.
Seit
vielen Jahren wird insbesondere in der Bevölkerungsgruppe der
über 65jährigen für die Grippeschutzimpfung geworben. Doch die
Frage des tatsächlichen - also messbaren - Nutzens dieser Impfung
ist weiter umstritten. Obgleich die Zahl der gegen eine Virusgrippe
geimpften älteren Personen seit 1980 von 15% auf auf 65%
gestiegen ist, konnte die im Umfeld einer Virusgrippe zu beobachtende
Sterblichkeit nicht erkennbar abgesenkt werden.
Die Autoren der Studie gehen davon aus, dass die derzeit verwendeten
Impfstoffe gerade bei älteren Menschen nicht sehr effektiv wirken.
Dessen ungeachtet empfehlen sie, ältere Menschen weiterhin im
Herbst gegen die Virusgrippe zu impfen. Das Risiko schwerer Grippe-Nebenwirkungen
ist bei den Senioren so hoch, dass selbst ein wenig effektiver
Impfstoff besser ist als kein Impfstoff.
pressoffice@lancet.com
Press Release
MORTALITY BENEFITS OF VACCINE PROGRAMME FOR THE ELDERLY GREATLY
EXAGGERATED
The mortality benefits of vaccinating elderly people against the
influenza virus have been greatly exaggerated, conclude authors
of a Review published in the October edition of The Lancet Infectious
Diseases.
Influenza vaccination policy in most high income countries attempts
to reduce the mortality burden of influenza by targeting people
aged at least 65 years for vaccination. Dr Lone Simonsen, George
Washington University, Washington, DC, USA and colleagues say
that frailty selection bias (ie, where not-so-frail elderly people
are vaccinated more often than their infirm peers), and the use
of non-specific trial endpoints such as all-cause mortality have
been the reasons behind this exaggeration.
They say: “The remaining evidence base is currently insufficient
to indicate the magnitude of the mortality benefit, if any, that
elderly people derive from the vaccination programme.”
The authors point out that although placebo-controlled randomised
trials show the influenza vaccine is effective
in younger adults, few trials have included elderly people,
and especially those aged at least 70 years, the age-group that
accounts for three-quarters of all influenza related deaths. Such
trials suggest that clinical benefits and antibody responses in
elderly people decline with increasing age past 70 years.
Further, they say that recent excess mortality
studies have been unable to confirm a decline in influenza-related
mortality since 1980, even as vaccination coverage increased from
15% to 65%.
The authors say: “Paradoxically, whereas those studies attribute
about 5% of all winter deaths to influenza, many cohort studies
report a 50% reduction in the total risk of death in winter—a
benefit ten times greater than the estimated influenza mortality
burden.”
They propose that future trials should use more specific endpoints,
eg. vaccine effectiveness against the highly specific outcome
of laboratory-confirmed influenza virus, which although labour
intensive and expensive, is more likely to obtain more realistic
estimates of vaccine efficacy. Future trials should also identify
the epidemic period for each season through use of actual virus
surveillance data, rather than the current arbitrary four-month
period.
They end with a note of caution, saying: “While awaiting an improved
evidence base for influenza vaccine mortality benefits in elderly
people, we suggest that this group should
continue to be vaccinated against influenza. Influenza causes
many deaths each year, and even a partly effective vaccine would
be better than no vaccine at all. But the evidence
base concerning influenza vaccine benefits in elderly people does
need to be strengthened.”
In an accompanying Comment published Online in The Lancet today,
Dr Tom Jefferson and Dr Carlo Di Pietrantonj, Cochrane Vaccines
Field, Alessandria, Italy say: “If current evidence points to
substantial uncertainty, then what next? Simonsen and colleagues
suggest that ‘refocusing on the likely complications of immune
senescence would require vigorous pursuit of other options’. They
also confront the ultimate taboo that drew so much scorn in the
evidence overview: doing randomised
trials in elderly people to settle the issue conclusively.
That suggestion, which seems to fly in the face of current policies,
is in our opinion the only ethical and scientific way to have
definitive answer to the question of whether or not current influenza
vaccines protect elderly people.”
Dr Lone Simonsen, George Washington University, Washington, DC,
USA. T)
Dr Lisa Jackson, Group Health Centre for Health Studies, Seattle,
WA, USA. T)
Dr Tom Jefferson and Dr Carlo Di Pietrantonj, Cochrane Vaccines
Field, Alessandria, Italy.
iphlxs@gwumc.edu
jefferson.tom@gmail.com
lmjackson@psc.gov
|
