LAIV vs IIV: Which is more effective for Influenza Prevention?

July 9, 2018

There is no difference in protection in children vaccinated with the live attenuated influenza vaccine (LAIV) and the inactivated influenza vaccine (IIV), according to the results of a recent study.

Previous research has reported conflicting results on the effectiveness of the LAIV, particularly against influenza A(H1N1)pdm09. For this reason, the authors of the recent study sought to compare the effectiveness of the LAIV and IIV against laboratory-confirmed influenza.


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They conducted a test-negative study involving 10,169 children and adolescents aged 2 to 17 years tested for influenza during the influenza seasons spanning November 11, 2012, to April 30, 2016 in Alberta, Canada. They used logistic regression to estimate effectiveness by vaccine type, influenza season, and influenza type and subtype.

Across the 4 seasons, 3161 children tested positive for influenza. Overall, the adjusted vaccine effectiveness was 69% for LAIV compared with 79% for IIV against influenza A(h1N1)pdm09, 36% for LAIV and 43% for IIV for influenza A(H3N2), and 74% for LAIV and 56% for IIV for influenza B. No significant differences in the odds of influenza infection, except for influenza B during the 2015-2016 season, were observed between LAIV and IIV recipients.

“There was no evidence to support the lack of effectiveness of LAIV against influenza A(H1N1)pdm09. These results support administration of either vaccine type in this age group.”

—Michael Potts


Buchan SA, Booth S, Scott AN, et al. Effectiveness of live attenuated vs inactivated influenza vaccines in children during the 2012-2013 through 2015-2016 influenza seasons in Alberta, Canada [published online July 2, 2018. JAMA Pediatr. doi:10.1001/jamapediatrics.2018.1514