Intranasally administered live attenuated influenza vaccine (LAIV) is once again an option for pharmacists and other vaccinators in the United States.
A recent article in the Morbidity & Mortality Weekly Report announces that for the 2018–19 U.S. influenza season, providers may choose to administer any licensed, age-appropriate influenza vaccine—either inactivated influenza vaccine (IIV), recombinant influenza vaccine [RIV], or LAIV4.
Authors from the CDC explain that no preference is expressed for any influenza vaccine product, and LAIV4 can be used when appropriate, based on guidelines.
They caution, however, that healthcare providers should be aware that the effectiveness of the updated LAIV4 containing A/Slovenia/2903/2015 against currently circulating influenza A(H1N1)pdm09-like viruses is not yet known. The LAIV4 vaccine was initially licensed in the U.S. in 2003 as a trivalent formulation (LAIV3) and marketed as FluMist.
“Review of LAIV effectiveness data for previous seasons in the United States confirms low to no significant effectiveness of LAIV against influenza A(H1N1)pdm09-like viruses,” the CDC authors write. “However, LAIV was generally effective against influenza B viruses and was of similar effectiveness to IIV against influenza A(H3N2) viruses.”
It also points out that data presented by the manufacturer indicates greater effectiveness than past formulations.
While the intranasal vaccine was not recommended beginning in the 2016-2017 influenza season, the CDC’s Advisory Committee on Immunization Practices reconsidered that stance. “Analyses of data from 2010–11 through 2016–17 indicate that LAIV was effective against influenza B viruses, and effectiveness against influenza A(H3N2) viruses was similar to that of inactivated influenza vaccines,” the article explains. “During this period, LAIV was poorly effective among children aged 2 through 17 years against influenza A(H1N1)pdm09 viruses in the United States. Shedding and immunogenicity data provided by the manufacturer suggest that the new influenza A(H1N1)pdm09-like virus included in the current LAIV4, A/Slovenia/2903/2015, has improved replicative fitness over previous LAIV4 influenza A(H1N1)pdm09-like vaccine strains.”
They add, “However, no published effectiveness estimates for this formulation of the vaccine against influenza A(H1N1)pdm09 viruses were yet available because influenza A(H3N2) and influenza B viruses have predominated during the 2017–18 Northern Hemisphere season.”
The CDC notes that national influenza vaccination coverage among children did not decline substantially overall during the 2016–17 season, the first season for which LAIV was not recommended. It adds that “overall vaccination coverage remains suboptimal. Additional options for vaccination of children, including use of noninjectable vaccines such as LAIV4, might provide a means to improve coverage, particularly in school-based settings.”