Systematic review of the efficacy, effectiveness and safety of newer and enhanced seasonal influenza vaccines

Erratum: On page 19, under the section '3.2.4.1 Serious adverse events' there was a mistake in the allocation of a death attributable to the aIIV vaccine group, which has now been corrected as being attributable to the IIV vaccine group [27 May 2025].

Overall the evidence base for the efficacy and effectiveness of newer and enhanced influenza vaccines appears limited at present, with a number of potentially relevant studies identified as ongoing.

It is likely that the use of such vaccines provides greater protection than no vaccination at all, when the usual considerations of circulating strain matching are applied. Evidence regarding the comparability of these vaccines to traditional seasonal influenza vaccines is uncertain with a lack of available literature.

The safety profiles of these vaccines are largely in keeping with that expected when considering their individual compositions and, for the most part, they appear to be well tolerated.

Some suggestions are provided to enhance research conduct and reporting regarding these newer and enhanced influenza vaccines which are anticipated to improve the data coverage overall and facilitate future decision-making regarding the use of such vaccines.