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Effect of Influenza Vaccination on Otitis Media in Young Children
Abstract & Commentary
Synopsis: Inactivated trivalent influenza vaccine did not reduce the incidence of acute otitis media among children 6-24 months of age.
Source: Hoberman A, et al. Effectiveness of inactivated influenza vaccine in preventing acute otitis media in young children. A randomized controlled trial. JAMA. 2003;290: 1608-1616.
A randomized, double-blind, placebo-controlled trial of inactivated trivalent subvirion influenza vaccine was conducted during 1999-2001 among 786 children aged 6-24 months. Children received 2 doses (0.25 mL each) of vaccine approximately 4 weeks apart. Testing the 66 serum samples collected from children in the vaccine group showed seroconversion rates of 88.6-96.8%, depending on the specific strain. Vaccine efficacy against culture-confirmed influenza was 66% (95% CI, 34%-82%) in 1999-2000, and -7% (95% CI, -247%-67%) in 2000-2001. However, the influenza attack rates were 15.9% and 3.3%, respectively.
The vaccine was well tolerated. Compared to placebo, influenza vaccine did not reduce the proportion of children with at least 1 episode of acute otitis media in the first cohort (1999) during the influenza season (vaccine, 30.5% vs 29.9%), during the respiratory season (vaccine, 49.2% vs placebo, 52.2%; P = .56), or during the entire 1-year follow-up period (vaccine, 57.3% vs 61.9%, P = .35). Nor did it reduce the proportion in the second cohort (vaccine, 55.8% vs placebo, 48.2%; P = .17). There were no differences between vaccine and placebo groups for the monthly rate of acute otitis media, the estimated proportion of time with middle ear effusion, or the use of health care and related resources.
Comment by Hal B. Jenson, MD, FAAP
There have been 4 previous studies, and now a fifth, of the efficacy of influenza vaccine and the possible effect on reduction of acute otitis media in children. Previous studies, some of which have shown a reduction in otitis media after influenza vaccination, have been limited by small sample size, study population selection, nonrandomization, single or incomplete blinding, and lack of standardized criteria for diagnosis. This study showed that the influenza vaccine for 2000-2001 did not have a significant effect on prevention of influenza in this age group; demonstrating this benefit with this number of patients was hampered because the incidence of influenza never reached epidemic proportions in this population during the study years.
There may be age-related factors that account for the different results of this study from previous studies. This study enrolled primarily children 18 months of age and younger (mean age, 14 months) compared to mean age ranges of 20-43 months in 3 of the previous studies. For example, in this study within the subgroup of children 19-24 months of age, the proportions of children who had at least 1 episode of acute otitis media during the influenza and respiratory seasons were suggestively lower in the vaccine group than in the placebo group (19.4% vs 34.3%; P = .10; and 36.8% vs 54.3%; P = .09, respectively). Age differences could account for some of the differences between studies if the proportion of viral respiratory infections caused by influenza are lower in younger children than in older children, or if the vaccine was less effective in preventing influenza in younger children than in older children. However, this study found seroconversion rates of approximately 90% in both years, with no difference in antibody responses by age group.
In October 2003, the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention recommended that influenza vaccine be provided to all healthy children 6-23 months of age with effective implementation in fall 2004. This recommendation strengthens the previous policy for this age group to a full recommendation. The benefits of the vaccine to reduce the rates of influenza in children and to reduce the burden of influenza in the community justify this new recommendation regardless of the limited effect on acute otitis media.
Dr. Jenson is FAAP Chair, Department of Pediatrics, Director, Center for Pediatric Research, Eastern Virginia Medical School and Children’s Hospital of the King’s Daughters, Norfolk, VA