Cochrane Reviews Efficacy of Vaccination To Prevent Flu In Healthy Adults Interview with:
“#influenza” by J.S. Zolliker is licensed under CC BY 2.0Dr. Vittorio Demicheli

Servizio Regionale di Riferimento per l’Epidemiologia
SSEpi-SeREMI, Azienda Sanitaria Locale ASL AL
Alessandria, Piemonte, Italy What is the background for this study? What are the main findings? 

Response: The consequences of influenza in adults are mainly time off work. Only vaccination of pregnant women is recommended internationally, while mass vaccination of healthy adults is still matter of debate.

The aim of this Cochrane Review is to assist informed decision making summarizing research that looks at the effects of immunizing healthy adults with influenza vaccines during influenza seasons.

The review process found 52 clinical trials of over 80,000 adults. Only around 15% of the included studies were well designed and conducted. We focused on reporting of results from 25 studies that looked at inactivated vaccines. Injected influenza vaccines probably have a small protective effect against influenza and influenza-like illness (ILI_ (moderate-certainty evidence), as 71 people would need to be vaccinated to avoid one influenza case, and 29 would need to be vaccinated to avoid one case of ILI. Vaccination may have little or no appreciable effect on hospitalizations (low-certainty evidence) or number of working days lost. What should readers take away from your report?

 Response: Inactivated vaccines can reduce the proportion of healthy adults (including pregnant women) who have influenza and ILI, but their impact is modest. We are uncertain about the effects of inactivated vaccines on working days lost or serious complications of influenza during influenza season. What recommendations do you have for future research as a result of this work? 

Response: When a new vaccination or preventive technology becomes available, an adequately powered, publicly funded, high-quality, placebo-controlled trial run over several seasons should be undertaken. New insights on the role of viruses and other agents in the genesis of influenza and ILI are also needed. Is there anything else you would like to add?

Response: This is an update of a review firstly published in 1999. Future updates of this review will be made only when 


Cochrane 1 February 2018
Vaccines to prevent influenza in healthy adults
Demicheli V, Jefferson T, Ferroni E, Rivetti A, Di Pietrantonj C

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Last Updated on February 12, 2018 by Marie Benz MD FAAD