The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) voted 12 to 2 Wednesday to recommend returning the nasal live attenuated influenza quadrivalent vaccine (LAIV4; FluMist, MedImmune) to its list of recommended influenza vaccines for the 2018-2019 influenza season, after rejecting it the last 2 years.
ACIP voted 11 to 3 not to recommend injectable vaccines over LAIV4, but rather to leave the choice of vaccines to the discretion of clinicians.
“I actually think that the effect of making a preferential recommendation now would be to suppress data going forward because potentially LAIV wouldn’t be used if we made a preferential recommendation right now and we have good evidence that LAIV is probably as good for [influenza] B and for H3N2 as [inactivated influenza vaccine (IIV)]…so I don’t think we have good compelling data that IIV is better than LAIV,” explained ACIP Chair Nancy Bennett, MD, professor of medicine and public health sciences, University of Rochester School of Medicine and Dentistry, New York.
The committee also voted unanimously to add LAIV4 to the Vaccines for Children (VFC) program. LAIV4 was not recommended during the 2017-2018 or 2016-2017 influenza seasons because it was poorly effective against circulating strains of influenza in the United States.
The wording of the VFC recommendations remains largely unchanged from the previous year.
About “Options”
Several committee members said they believe providing a nasal vaccine option will enable people to receive vaccinations who might otherwise be unwilling to receive an injectable vaccination, a common sentiment voiced at the June 2016 ACIP meeting when the committee voted to recommend against the vaccine.
“I feel like ‘give people as many options to be vaccinated,’ because being vaccinated is better than not being vaccinated. [T]o now take the next step and have a preference over which one of those vaccines is taking a step for which I’m not sure the data’s all that compelling,” said Laura E. Riley, MD, associate professor of obstetrics, gynecology, and reproductive biology, Harvard Medical School, and vice chair of obstetrics, maternal-fetal medicine, Massachusetts General Hospital, Boston.
The committee’s votes followed a discussion of data from a study of 200 US children aged 2 years to younger than 4 years that used a new 2017-2018 H1N1 LAIV postpandemic strain (A/Slovenia) in the study vaccine instead of the formerly used 2015-2016 H1N1 LAIV postpandemic strain (A/Bolivia), which had shown reduced effectiveness. The researchers randomly assigned the children to receive a trivalent vaccine containing A/Bolivia, a quadrivalent vaccine containing A/Bolivia, or a quadrivalent vaccine containing A/Slovenia.
The study’s primary endpoint was the proportion of participants with strain-specific hemagglutination inhibition assay (HAI) antibody seroconversion (≥4-fold increase) through days 28 and 56. Secondary endpoints were immunogenicity, shedding of vaccine virus, and safety.
The new study showed high effectiveness similar to that seen with the H1N1 LAIV strain used in the vaccine prior to the 2009 influenza pandemic. A higher proportion of children shed the A/Slovenia strain from day 4 through day 7. HAI seroconversion rates were significantly higher among children who received the A/Slovenia strain compared with those who received vaccine with the A/Bolivia strain; therefore, the study met its primary endpoint. HAI seroconversion rates for A/Slovenia were similar to those found among same-aged children who received vaccines with a highly efficacious prepandemic H1N1 strain.
“This study validates the improvements we’ve made to our strain selection process and confirms an improved H1N1 LAIV strain was included in the 2017-2018 formulation. We are pleased that the ACIP has voted in support of a renewed recommendation for FluMist Quadrivalent in the US and look forward to continuing to work with public health authorities to optimize protection against influenza,” said Gregory Keenan, vice president, US Medical Affairs, AstraZeneca, in a news release.
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