Nasal Flu Vaccine Underperforms Compared With IIV

New research has shown that the live attenuated influenza vaccine (LAIV4) was less effective for the prevention of influenza, especially A/H1N1, compared with inactivated influenza vaccine (IIV).

Previous research into the effectiveness of LAIV4 compared with IIV in children and adolescents has produced inconsistent results.

Using data from 5 US studies from 2013-2014 through 2015-2016, the researchers compared the vaccine effectiveness of LAIV4 and IIV against laboratory-confirmed influenza in patients aged 2 to 17 years.

Of the 17,173 patients included in the study, 4579 received IIV, 1979 received LAIV4, and 10,615 were unvaccinated. Overall, vaccine effectiveness against A/H1N1pdm09 was 67% for IIV and 20% for LAIV4, with similar results when stratified by vaccination in the previous season. Those who were given LAIV4 also had significantly higher odds of contracting influenza A/H1N1pdm09 than those who were given IIV (odds ratio 2.66). Effectiveness against influenza A/H3N2 and B were similar between the 2 vaccines.

“From this pooled individual patient–level data analysis, we found reduced effectiveness of LAIV4 against influenza A/H1N1pdm09 compared with IIV, which is consistent with published results from the individual studies included.”

—Michael Potts

Reference:

Chung JR, Flannery B, Ambrose CS, et al. Live attenuated and inactivated influenza vaccine effectiveness [published online January 7, 2019]. Pediatrics. doi: 10.1542/peds.2018-2094.