According to the CDC’s own website, the LIVE nasal attenuated influenza quadrivalent vaccine (LAIV4; FluMist, MedImmune) was not recommended for use in 2018.
However, on Wednesday, the Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) voted 12 to 2 to reverse the decision they have held for the last two years, returning the vaccine to its list of recommended influenza vaccines for the 2018-2019 influenza season. (They 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.1)
Many of the committee members felt that providing a nasal vaccine option would encourage people who are unwilling to receive an injectable vaccination, to get one. 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, said: “I feel like ‘give people as many options to be vaccinated,’ because being vaccinated is better than not being vaccinated… ” 2 (Sure, gotta keep those numbers up!)
The committee came to their decision after a discussion of the 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). (WHO IS SIGNING THEIR CHILDREN UP TO BE PART OF A VACCINE STUDY?)
Researchers randomly assigned each child the trivalent vaccine containing A/Bolivia, the quadrivalent vaccine containing A/Bolivia, or a quadrivalent vaccine containing A/Slovenia with the study’s primary endpoint being “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.”3
What the study found was “high effectiveness” similar to what had been seen with the H1N1 LAIV strain used in the vaccine prior to the 2009 influenza pandemic. But what we can’t tell you is what that effectiveness is. And, still present in the study was the fact that a high number of those kids were still shedding the A/Slovenia strain from day 4 through day 7.
For their part, AstraZeneca, creators of the vaccine, are rather pleased.