John: Hello, I'm John Hilton, editor in the Cochrane Editorial and Methods department. Acute otitis media is a common infection in children, with research showing that up to four in every five children in high-income countries will have at least one episode by the age of three. Influenza vaccines have been suggested as a way to prevent this, and an updated Cochrane Review from October 2017 looks at the latest evidence. Here’s the review’s lead author, Norhayati from the Universiti Sains Malaysia in Kubang Kerian, Malaysia, to tell us more.

Norhayati: Although people used to think that acute otitis media, or AOM as I’ll call it in this podcast, was caused by a virus, more recently it has been found that most AOM is bacterial in origin. However, it is commonly triggered by a viral infection, such as influenza, and this raises the possibility that influenza vaccines might not only prevent influenza but might also be effective in preventing AOM. Knowing whether or not this is the case might help parents making a decision to vaccinate their children against influenza, and our review does suggest that there might be a small reduction in AOM and a larger effect on the use of antibiotics.
We investigated this by reviewing trials that had compared influenza vaccines with placebo or no treatment in children between six months and six years of age, whether or not they had had AOM in the past. We included 11 trials but several of these did not contribute to our analyses, because their follow-up period was too short. However, by doing a meta-analysis of the other four trials with more than 3000 participants, we found a 4% absolute reduction in episodes of AOM in vaccinated children in the 6 months after vaccination. Even more importantly, there was a clinically meaningful 11% absolute reduction in children receiving antibiotics for AOM or its complications in our analysis of the 1200 children in two trials. 
There were some adverse events with the vaccine but the reporting of these was limited to minor side effects, including episodes of fever and a runny nose. However, it is important to note that some rare or serious adverse events have been reported in the Cochrane Review that focuses on the efficacy and safety of influenza vaccine in children, which includes a larger collection of studies than our review. 
In summary, influenza vaccine appears to have a small effect in reducing AOM in young children but promoting influenza vaccination solely to reduce AOM does not seem justified. On the other hand, the benefits of the vaccine on reducing antibiotic usage might justify its use; but, in settings with a low incidence of mastoiditis, an important complication of AOM, where 'watchful waiting' is already used to reduce the over-prescribing of antibiotics, the impact of this finding is uncertain.

John: If you would like to read more about influenza vaccine and acute otitis media, just go online to Cochrane Library dot com and search 'influenza vaccines for otitis media' to find Norhayati's review. While, if you want to find the review he mentioned of the effects of the vaccine on influenza itself, search 'vaccines for preventing influenza in healthy children'.