In new twist following CDC rebuke, study finds AZ's FluMist effective


Following the June decision by a CDC committee to recommend against use of AstraZeneca’s ($AZN) FluMist Quadrivalent for the upcoming flu season, a Canadian study published this week found the trivalent version of the vaccine was as effective as an inactivated flu shot over three seasons.

For their study in 52 Hutterite communities in Canada, researchers tested FluMist compared to a trivalent inactivated flu shot in 1,186 children aged 3 to 15, finding that 5.3% of the FluMist group contracted the viral infection compared to 5.2% for the flu shot group over a three-year span.

The data are similar to results from earlier studies that supported FluMist’s effectiveness, NPR reports, at least until 2013, when the vaccine went from covering three flu strains to four.

While the work adds information to the picture surrounding FluMist, it won’t clear up the cause of the vaccine’s dramatic efficacy dropoff cited by CDC’s Advisory Committee on Immunization Practices in its decision to recommend against using FluMist for the upcoming season. In speaking with NPR’s Shots, Baylor College of Medicine professor of virology and microbiology Pedro Piedra said “something happened when it became a quadrivalent vaccine."

After previously recommending AstraZeneca’s quadrivalent nasal flu vaccine, ACIP in June said "no protective benefit could be measured" from FluMist for the previous three flu seasons. For children aged two to 17 during the 2015-2016 season, the vaccine was just 3% effective, according to data the committee received in May.

AstraZeneca however said the numbers contradicted its own as well as findings from studies by independent health authorities in the U.K. and Finland. The company said its vaccine was 46% to 58% effective overall last season. The pharma added that it was working “to better understand” the decision and to ensure the vaccine is available for future seasons.

The FluMist challenges for AstraZeneca come at an especially competitive time in the flu vaccine market. A new player has joined the quadrivalent fray--Seqirus, formed last year from the joining of bioCSL and Novartis’ flu vaccines--and received FDA approval in May for its Flucelvax Quadrivalent. Seqirus will now contend with Big Pharma players in the race for control of the four-strain vaccine market.

The Canadian study covered 2012 to 2015 and was published in Annals of Internal Medicine.

- here’s the NPR story
- and the study

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