Influenza vaccine reduced AOM, antibiotic use among children with uncomplicated recurrent episodes

Administering influenza vaccine to children with recurrent acute otitis media significantly reduced related morbidity but was less effective among children who had repeated tympanic membrane perforation, data from an Italian study indicated.

Researchers from the University of Milan and the Mario Negri Institute for Pharmacological Research, also in Milan, randomly assigned 180 children aged 1 to 5 years with a history of recurrent AOM who were previously unvaccinated against influenza to either inactivated virosomal-adjuvanted influenza vaccine (Inflexal V, Berna Biotech) or no vaccine. They monitored AOM–related morbidity every four to six weeks for six months and found the following among vaccinated children:

Fewer children experienced an AOM episode.
The mean number of AOM episodes was lower (P=.03), as was the number of AOM episodes without tympanic membrane perforation.
Fewer antibiotic courses were administered.
The mean duration of bilateral otitis media with effusion was shorter.
Absence of a history of recurrent perforation was the only factor significantly associated with greater vaccine efficacy for preventing AOM.

Despite a lack of etiologic data from this study, the researchers suggested that differences in vaccine efficacy among children with and without tympanic membrane perforation may be explained by variations in the causative pathogens. Data from a prior study indicated that AOM caused by Streptococcus pyogenes was more likely to result in tympanic membrane perforationcompared with AOM caused by other pathogens.

“It seems reasonable to think that the efficacy of influenza vaccine in our population may have been at least partially due to its preventing pneumococcal AOM, whereas its lesser efficacy in children with a history of recurrent perforation may have been the result of a higher incidence of AOM caused by S. pyogenes, a pathogen with no demonstrated higher risk for infection following influenza,” the researchers wrote.

The efficacy of influenza vaccine in preventing AOM among populations universally vaccinated with pneumococcal conjugate vaccine may also be limited, according to the researchers. They acknowledged that the number of children who were administered pneumococcal conjugate vaccine was too small to monitor its affect on study outcomes.

“Further studies are needed to clarify the characteristics of the children with a history of recurrent AOM who may benefit more from the use of influenza vaccine,” the researchers wrote.

Marchisio P. Pediatr Infect Dis J. 2009;28:855-859.

PERSPECTIVE

If a child contracts influenza, like other respiratory viruses, it may facilitate the development of an AOM. Vaccination with influenza vaccine therefore might prevent one episode of AOM. If there are multiple strains of influenza — like an A strain and a B strain, or this year, the extra possibility of an H1N1 strain — then each influenza illness prevented by vaccination may prevent one episode of AOM. I now lead a group of 21 researchers working on understanding how viruses modulate the innate and adaptive immune system to facilitate bacterial AOM, and we are seeking to find or participate in the development of a multicomponent AOM vaccine.

– Michael E. Pichichero, MD

Infectious Diseases in Children Editorial Board