The flu shot versus flu nasal spray—which is more effective?

In a study of pediatric patients, vaccine coverage in both LAIV and IIV groups was similar.
In a study of pediatric patients, vaccine coverage in both LAIV and IIV groups was similar.

Intranasal live attenuated influenza vaccine (LAIV) and inactivated influenza vaccine (IIV) provide similar community protection against the influenza virus, according to research published in the Annals of Internal Medicine.

During the course of 3 flu seasons, Mark Loeb, MD, professor, Department of Pathology and Molecular Medicine, McMaster University, Ontario, and colleagues conducted a cluster randomized, blinded trial to determine the efficacy of intranasal LAIV vs IIV in a cohort of children from 52 Hutterite colonies across Alberta and Saskatchewan.

The researchers randomly assigned the pediatric participants (n=1186) to receive a standard dose of either trivalent LAIV or trivalent IIV. The primary study outcome was reverse transcriptase polymerase chain reaction-confirmed influenza A or B virus in both vaccinated and unvaccinated participants.

Within the LAIV group, influenza virus occurred at a rate of 5.3%, vs 5.2% in the IIV group (295 of 5560 person-years, and 304 of 5810 person-years, respectively). Mean vaccination coverage among pediatric participants was 76.9% in the LAIV group vs 72.3% in the IIV group.

“Immunizing children with LAIV does not provide better community protection against influenza than IIV,” concluded Dr Loeb. He noted that the main constraint of the study – conducting it in Hutterite communities – may limit the generalizability of the results.

Previously, the CDC's Advisory Committee on Immunization Practices (ACIP) advised that LAIV should not be used during the 2016-2017 flu season. Clinicians should continue to vaccinate patients via either the IIV or recombinant influenza vaccine (RIV) in all patients 6 months and older.

References

  1. Loeb M, Russell ML, Manning V, et al. Live attenuated versus inactivated influenza vaccine in Hutterite children: A cluster randomized blinded trial. Ann Intern Med. 2016; doi: 10.7326/M16-0513
  2. ACIP votes down use of LAIV for 2016-2017 flu season [news release]. Atlanta, GA: Centers for Disease Control and Prevention. Published June 22, 2016. Accessed August 23, 2016.
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