Zusammenfassung
Influenzaviren haben eine hohe Variabilität. Entsprechend sollte jährlich mit einem aktuellen Impfstoff geimpft werden. Die Schutzwirkung hängt wesentlich von der Übereinstimmung der im Impfstoff enthaltenen Virusvarianten mit den tatsächlich zirkulierenden Varianten ab und kann von Saison zu Saison schwanken. Daher sind regelmäßige Studien zur Schutzwirkung der Impfung wichtig. Aufgrund des hohen Aufwandes kontrollierter Studien sind Schätzungen der Schutzwirkung anhand routinemäßig erhobener Daten, z. B. im Rahmen der Surveillance von Interesse. Wir vergleichen im vorliegenden Beitrag 2 Methoden zur Berechnung der Effektivität eines Impfstoffes: (1) die Screening-Methode (Ansatz 1), bei der Daten zur Impfrate in der Bevölkerung als Kontrollen verwendet werden; (2) die Methode 2 (Ansatz 2), die die gleichen laborbestätigten Influenzafalldaten wie Ansatz 1 betrachtet, aber als Kontrollen labornegative ILI-Erkrankte einsetzt. Die Sensitivität dieser Ansätze gegenüber als bedeutsam erachteten Confoundern wurde mithilfe einer Simulation abgeschätzt. Wir haben beide Methoden auf die in Deutschland im Rahmen der Surveillance durch die Arbeitsgemeinschaft Influenza (AGI) anfallenden Daten der Saison 2004/05 angewendet. Über alle Altersgruppen sind die mit beiden Methoden geschätzten Schutzraten gering, aber mit anderen Beobachtungen aus der Literatur vergleichbar. Unterschiede bei den Altersgruppen zwischen den Methoden und deutliche Unterschiede zwischen einzelnen Altersgruppen innerhalb einer Methode müssen im Zusammenhang mit dem kleinen Stichprobenumfang in den Altersraten gesehen werden, können jedoch auch als Hinweis auf bisher nicht berücksichtigte Confounder gewertet werden. Die absoluten Schätzwerte der Schutzraten sollten daher sehr vorsichtig interpretiert werden, aber eine relative Betrachtung über die verschiedenen Saisons ist sinnvoll.
Abstract
The continuous antigenic drift of influenza viruses requires annual adaptation of the vaccine. Protection depends largely on the match of the variants represented in the vaccine with the viruses actually known to be in circulation and may differ considerably from season to season. Therefore studies to assess the efficacy and effectiveness of the vaccine are conducted rather sporadically on an annual basis and it would be desirable to make use of routinely available data from surveillance programs. We compared two different approaches: (1) the “screening method” where cases are identified from laboratory data and controls are taken from data on vaccination rates and (2) a second method that uses the same cases, but controls were influenza-negative individuals with influenza-like illness (also identified from laboratory data). The sensitivity of the methods to confounders that were considered as relevant was tested with a simulation. Both methods were applied to the data of the German influenza surveillance data of the season 2004/2005. The estimated effectiveness over all age groups was rather low with both methods, but comparable with other estimations from the literature. We observed differences in certain age groups between the methods as well as large differences between particular age groups within one method. Possible explanations are random variations due to low numbers in age strata and other influences not yet considered. Therefore the estimations should be interpreted with care; however, relative comparisons among seasons may still be meaningful.
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Uphoff, H., Hauri, A.M., Schweiger, B. et al. Zur Schätzung der Schutzwirkung der Influenzaimpfung aus Surveillancedaten. Bundesgesundheitsbl - Gesundheitsforsch - Gesundheitsschutz 49, 287–295 (2006). https://doi.org/10.1007/s00103-006-1233-8
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DOI: https://doi.org/10.1007/s00103-006-1233-8