The live attenuated influenza vaccine was less effective against the influenza A/H1N1pdm09 virus in children and adolescents across multiple influenza seasons between 2013 and 2016, compared with the inactivated influenza vaccine, according to research published in the journal.
Jessie R. Chung, MPH, from the influenza division at the Centers for Disease Control and Prevention in Atlanta, and her colleagues performed an analysis of five different studies where vaccine effectiveness (VE) was examined for quadrivalent live attenuated vaccine (LAIV4) and inactivated influenza vaccine (IIV) in children and adolescents aged 2-17 years from 42 states.
The analysis included data from the U.S. Influenza Vaccine Effectiveness Network (6,793 patients), a study from the Louisiana State University Health Sciences Center (3,822 patients), the Influenza Clinical Investigation for Children (3,521 patients), Department of Defense Global, Laboratory-based, Influenza Surveillance Program (1,935 patients), and the Influenza Incidence Surveillance Project (1,102 patients) between the periods of 2013-2014 and 2015-2016. The researchers sourced current and previous season vaccination history from electronic medical records and immunization registries.
Of patients who were vaccinated across all seasons, there was 67% effectiveness against influenza A/H1N1pdm09 (95% confidence interval, 62%-72%) for those who received the IIV and 20% (95% CI, −6%-39%) for LAIV4. Among patients who received the LAIV4 vaccination, there was a significantly higher likelihood of developing influenza A/H1N1pdm09 (odds ratio, 2.66; 95% CI, 2.06-3.44) compared with patients who received the IIV vaccination.
With regard to other strains, there was similar effectiveness against influenza A/H3N2 and influenza B with LAIV4 and IIV vaccinations.
“In contrast to findings of reduced LAIV4 effectiveness against influenza A/H1N1pdm09 viruses, our results suggest a possible but nonsignificant benefit of LAIV4 over IIV against influenza B viruses, which has been described previously,” the investigators wrote.
Limitations of the study included having data only one season prior to enrollment and little available demographic information beyond age, gender, and geographic location.
The Influenza Clinical Investigation for Children was funded by MedImmune, a member of the AstraZeneca Group. Two of the researchers are employees of AstraZeneca. The other authors reported having no conflicts of interest. The U.S. Influenza Vaccine Effectiveness Network was supported by the CDC through cooperative agreements with the University of Michigan, Kaiser Permanente Washington Health Research Institute, Marshfield Clinic Research Institute, University of Pittsburgh, and Baylor Scott & White Health. At the University of Pittsburgh, the project also was supported by the National Institutes of Health.
SOURCE: Chung JR et al. Pediatrics. 2018. doi: .