Blindsided? FDA Ponders CDC’s ‘Ineffective’ Rating of FluMist

When FDA declares a therapy safe and effective for its labeled indication, what happens when a sister agency — in this case, the Centers for Disease Control and Prevention (CDC) — subsequently declares it ineffective for that indication and recommends use of a different product instead? That’s what happened 6/23 when CDC issued a news release saying its Advisory Committee on Immunization Practices had just voted that MedImmune’s FluMist live attenuated influenza vaccine should not be used during the 2016-2017 flu season because new preliminary data from the 2015-16 flu season on its effectiveness among children 2-17 years showed only a 3% effectiveness rate, meaning “no protective benefit could be measured.” This, CDC said, followed showings of poor and/or lower than expected FluMist effectiveness in each of the two previous flu seasons. CDC said flu shots should be used from now on instead of FluMist.

So what was the value of FDA’s determination of effectiveness when it approved FluMist in June of 2003? In a 6/17/03 news release announcing this approval, the agency said the vaccine had an 87% effectiveness rate in 10,000 children aged 15-17 who had been studied in clinical trials supporting MediImmune’s BLA. A review of FDA’s annual approval supporting materials for FluMist since 2003 revealed no FDA or MedImmune concerns about its effectiveness. Likewise, FDA’s latest version of the approved package insert for FluMist shows no concerns about effectiveness.

Historically, FDA safety determinations are expected to be revised as new, real-world information comeS in from widening public exposures to the product. But FDA effectiveness determinations are not known to ever change.

So what suddenly happened? Asked whether FDA agrees with CDC’s sudden trashing of its effectiveness determination for FluMist 13 years after the fact, press officer Tara Goodin was non-committal, saying in an email response: “Right now, we are reviewing the committee’s recommendations as we consider all options moving forward.”

Could that be government code for: “CDC blindsided us!” ??

Meanwhile, AstraZeneca, which owns MedImmune, said in a statement that CDC’s effectiveness data for 2015-2016 season “contrast with studies by AstraZeneca as well as preliminary independent findings by public health authorities in other countries. These findings demonstrate FluMist Quadrivalent was 46-58% effective overall against the circulating influenza strains during the 2015-2016 season. As influenza vaccine effectiveness varies from season to season, it is evaluated in annual observational studies. The CDC states that when there is a good match between the strains in the vaccine and those that circulate during the flu season, vaccines are typically 50-60% effective. AstraZeneca is working with the CDC to better understand its data to help ensure eligible patients continue to receive the vaccine in future seasons in the U.S.”