OBJECTIVES: To assess the effectiveness of influenza vaccine in reducing the occurrence of acute otitis media (AOM) in infants and children.
SEARCH METHODS: We searched CENTRAL (2014, Issue 6), MEDLINE (1946 to July week 1, 2014), EMBASE (2010 to July 2014), CINAHL (1981 to July 2014), LILACS (1982 to July 2014), Web of Science (1955 to July 2014) and reference lists of articles to July 2014.
SELECTION CRITERIA: Randomised controlled trials (RCTs) comparing influenza vaccine with placebo or no treatment in infants and children aged younger than six years old. We included children of either sex and of any ethnicity, with or without a history of recurrent AOM.
DATA COLLECTION AND ANALYSIS: Two review authors independently screened studies, assessed trial quality and extracted data. We performed statistical analyses using the random-effects and fixed-effect models and expressed the results as risk ratio (RR), risk difference (RD) and number needed to treat to benefit (NNTB) for dichotomous outcomes, with 95% confidence intervals (CI).
MAIN RESULTS: We included 10 trials (six trials in high-income countries and four multicentre trials in high-, middle- and low-income countries) involving 16,707 children aged six months to six years. Eight trials recruited participants from a healthcare setting. Nine trials (and all five trials that contributed to the primary outcome) declared funding from vaccine manufacturers. Four trials reported adequate allocation concealment and nine trials reported adequate blinding of participants and personnel. Attrition was low for all trials included in the analysis.The primary outcome showed a small reduction in at least one episode of AOM over at least six months of follow-up (five trials, 4736 participants: RR 0.80, 95% CI 0.67 to 0.96; RD -0.04, 95% CI -0.07 to -0.02; NNTB 25, 95% CI 15 to 50).The subgroup analyses (i.e. number of courses, settings, seasons or types of vaccine administered) showed no differences.There was a reduction in the use of antibiotics in vaccinated children (two trials, 1223 participants: RR 0.70, 95% CI 0.59 to 0.83; RD -0.15, 95% CI -0.30 to -0.00).There was no significant difference in the utilisation of health care for the one trial that provided sufficient information to be included. The use of influenza vaccine resulted in a significant increase in fever (six trials, 10,199 participants: RR 1.15, 95% CI 1.06 to 1.24; RD 0.02, 95% CI -0.00 to 0.05) and rhinorrhoea (six trials, 10,563 children: RR 1.17, 95% CI 1.07 to 1.29; RD 0.09, 95% CI 0.01 to 0.16) but no difference in pharyngitis. No major adverse events were reported.Compared to the protocol, the review included a subgroup analysis of AOM episodes by season, and changed the types of influenza vaccine from a secondary outcome to a subgroup analysis.
AUTHORS' CONCLUSIONS: Influenza vaccine results in a small reduction in AOM. The observed reduction with the use of antibiotics needs to be considered in the light of current recommended practices aimed at avoiding antibiotic overuse. Safety data from these trials are limited. The benefits may not justify the use of influenza vaccine without taking into account the vaccine efficacy in reducing influenza and safety data. The quality of the evidence was high to moderate. Additional research is needed.
OBJECTIVES: To assess the effectiveness of influenza vaccine in reducing the occurrence of acute otitis media in infants and children.
SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, LILACS, Web of Science, the WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov (15 February 2017). We also searched the reference lists of included studies to identify any additional trials.
SELECTION CRITERIA: Randomised controlled trials comparing influenza vaccine with placebo or no treatment in infants and children aged younger than six years. We included children of either sex and of any ethnicity, with or without a history of recurrent AOM.
DATA COLLECTION AND ANALYSIS: Two review authors independently screened studies, assessed trial quality, and extracted data. We performed statistical analyses using the random-effects and fixed-effect models and expressed the results as risk ratio (RR), risk difference (RD), and number needed to treat for an additional beneficial outcome (NNTB) for dichotomous outcomes, with 95% confidence intervals (CI).
MAIN RESULTS: We included 11 trials (6 trials in high-income countries and 5 multicentre trials in high-, middle-, and low-income countries) involving 17,123 children aged 6 months to 6 years. Eight trials recruited participants from a healthcare setting. Ten trials (and all four trials that contributed to the primary outcome) declared funding from vaccine manufacturers. Four trials reported adequate allocation concealment, and 10 trials reported adequate blinding of participants and personnel. Attrition was low for eight trials included in the analysis.The primary outcome showed a small reduction in at least one episode of AOM over at least six months of follow-up (4 trials, 3134 children; RR 0.84, 95% CI 0.69 to 1.02; RD -0.04, 95% CI -0.08 to -0.00; NNTB 25, 95% CI 12.5 to 100; low-quality evidence).The subgroup analyses (i.e. number of courses and types of vaccine administered) showed no differences.There was a reduction in the use of antibiotics in vaccinated children (2 trials, 1223 children; RR 0.70, 95% CI 0.59 to 0.83; RD -0.11, 95% CI -0.16 to -0.06; moderate-quality evidence).We were unable to demonstrate whether there was any difference in the utilisation of health care. The use of influenza vaccine resulted in a significant increase in fever (7 trials, 10,615 children; RR 1.15, 95% CI 1.06 to 1.24; RD 0.02, 95% CI 0.00 to 0.04; low-quality evidence), rhinorrhoea (6 trials, 10,563 children; RR 1.17, 95% CI 1.07 to 1.29; RD 0.09, 95% CI 0.01 to 0.16; low-quality evidence), but no difference in pharyngitis. No major adverse events were reported.Differing from the protocol, the original publication of the review included a subgroup analysis of AOM episodes by season, and the secondary outcome 'types of influenza vaccine' was changed to a subgroup analysis. For this update, we removed the subgroup analyses for trial setting, season, and utilisation of health care due to the small number of trials involved. We removed Belshe 2000 from primary and secondary outcomes (courses of vaccine and types of vaccine) because it reported episodes of AOM per person. We did not perform a subgroup analysis by type of adverse event. We have reported each type of adverse event as a separate analysis.
AUTHORS' CONCLUSIONS: Influenza vaccine results in a small reduction in AOM. The observed reduction in the use of antibiotics needs to be considered in light of current recommended practices aimed at avoiding antibiotic overuse. Safety data from these trials were limited. The benefits may not justify the use of influenza vaccine without taking into account the vaccine efficacy in reducing influenza and safety data. We judged the quality of the evidence to be low to moderate. Additional research is needed.
MATERIALS AND METHODS: During the period from 16 to 21 March 2007, outbreak investigations and active case finding were carried out among residents and nursing staff at the welfare home. Interviews and medical notes review were conducted to obtain epidemiological and clinical data. Hospitalised patients were tested for respiratory pathogens. Further genetic studies were also carried out on positive respiratory samples.
RESULTS: The overall clinical attack rate was 9.4% (17/180) in residents and 6.7% (2/30) in staff. All infected residents and staff had received influenza immunisation. Fifteen residents were hospitalised, with 2 developing severe complications. Genetic sequencing revealed that the outbreak strain had an 8.2% amino acid difference from B/Malaysia/2506/2004, the 2006 southern hemisphere influenza vaccine strain, which the residents and staff had earlier received.
CONCLUSIONS: A mismatch between the vaccine and circulating influenza virus strains can result in an outbreak in a highly immunised LTCF resident population. Active surveillance for acute respiratory illness in LTCFs could be implemented for rapid detection of antigenic drift. Enhanced infection control and other preventive measures can then be deployed in a timely manner to mitigate the effect of any outbreaks.