Major Finding: The pooled efficacy of LAIV against influenza-associated AOM was 91.4% versus placebo and 62.7% versus TIV.
Data Source: A meta-analysis of five randomized, double-blind, placebo-controlled trials in 7,062 children aged 24–83 months involving LAIV, and two randomized, double-blind, TIV-controlled trials in 5,775 children aged 24–71 months comparing LAIV and TIV.
Disclosures: MedImmune Inc. sponsored the research, and two of the coauthors are MedImmune employees. Dr. Block said he receives support from several pharmaceutical companies, including MedImmune.
ATLANTA — The live attenuated influenza vaccine appears to significantly reduce influenza-associated acute otitis media in children aged 24–83 months, according to a meta-analysis by Dr. Stan L. Block Jr.
The reduction was significant compared with placebo and trivalent inactivated influenza vaccine (TIV), said Dr. Block of the University of Kentucky in Lexington and his colleagues in a poster at the National Immunization Conference sponsored by the Centers for Disease Control and Prevention.
This was true when all cases of influenza were considered, but the reduction was no longer statistically significant for TIV when only children with confirmed influenza were considered.
Investigators pooled data about the incidence of influenza-associated acute otitis media (AOM) in five randomized, double-blind, placebo-controlled trials in children aged 24–83 months (live attenuated influenza vaccine [LAIV], n = 4,278; placebo, n = 2,784) and two randomized, double-blind, TIV-controlled trials in children aged 24–71 months (LAIV, n = 2,872; TIV, n = 2,903).
Influenza was detected by viral culture; all strains were included. AOM was diagnosed clinically. The subjects included healthy children, those with frequent respiratory infections, and those in day care.
The pooled efficacy of LAIV against influenza-associated AOM was 91.4% (0.3% vs. 3.0%) for placebo and 62.7% (0.4% vs. 1.0%) for TIV, the researchers reported.
When only those children with confirmed influenza were considered, AOM was diagnosed in 7.6% of the 145 LAIV recipients and in 17.6% of the 473 placebo recipients, for a 56.8% relative reduction in AOM cases.
In the TIV-controlled studies, AOM was diagnosed in 9.4% of the 117 LAIV recipients and in 11.6% of the of 251 TIV recipients. The relative reduction of 18.6% was not statistically significant.
In an interview, Dr. Seth L. Toback, director of medical affairs at MedImmune and one of the coinvestigators, speculated that the protective effect of LAIV could be related to mucosal protection or cell-mediated immunity—the same reason it protects against the flu, but he stressed that this research does not address that issue.
The reduction was significant compared with placebo and trivalent inactivated influenza vaccine.
Source DR. BLOCK