INFLUENZA-A VACCINE DECREASES THE INCIDENCE OF OTITIS-MEDIA IN 6- TO 30-MONTH-OLD CHILDREN IN DAY-CARE

Objective: To determine if the use of influenza vaccine in children in day care decreases the incidence of otitis media during the influenza season. Design: Prospective cohort study. Setting: Eight day-care centers in North Carolina. Participants: One hundred eighty-six children aged 6 to 30 months. Intervention: Half the participants received trivalent subvirion influenza virus vaccine. Measurements: Acute otitis media (AOM) and serous otitis media (SOM) were assessed biweekly from mid-November 1993 to mid-March 1994 by visual and tympanometric examinations performed by ''blinded'' observers. The winter season was divided into three periods - before, during, and after influenza season - and the number of children with AOM, or SOM during each period was determined. Unadjusted and adjusted odds ratios (ORs) were computed, while controlling for race and sex using logistic regression methods. Results: Influenza vaccine was protective against AOM (OR=0.69, 95% CI, 0.49-0.98) during the influenza season. Although there may have been some protection against SOM (OR=0.75, 95% CII 0.54-1.02) statistical significance was not achieved. Myringotomy tubes were also significantly protective against AOM and SOM during all three time periods, with ORs between 0.34 and 0.52, but the greatest protection was seen during the influenza period. Conclusions: Influenza vaccination of 6- to 30-month-old children in day care was associated with a decreased incidence of otitis media during the influenza season. Myringotomy tubes protected against AOM and SOM during all 16 weeks monitored.