Pneumococcal conjugate vaccines for preventing otitis media

Background Acute otitis media (AOM) is a very common early infancy and childhood disease. The marginal benefits of antibiotics on AOM, the increasing problem of bacterial resistance to antibiotics, and the huge estimated direct and indirect annual costs associated with otitis media (OM) have prompted a search for effective vaccines to prevent AOM. Objectives To assess the effect of pneumococcal conjugate vaccines (PCVs) in preventing AOM in children up to 12 years of age. Search strategy We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, issue 2), which contains the Cochrane Acute Respiratory Infections Group's Specialised Register; MEDLINE (January 1995 to November 2007); and EMBASE (January 1995 to November 2007). Selection criteria Randomised controlled trials of PCVs to prevent AOM in children aged 12 years or younger, with a follow up of at least six months after vaccination. Data collection and analysis Three review authors independently assessed trial quality and two review authors extracted data. Main results We included seven trials on 7- to 11-valent PCV (with different carrier proteins). There was large heterogeneity regarding study population, type of conjugate vaccine, and outcome measures between trials, therefore, results were not pooled. The only currently licensed 7- valent PCV Prevenar with CRM197 as carrier protein (CRM197-PCV7) administered during infancy was in two studies associated with a 6% (95% confidence interval (CI) - 4% to 16%) and 7% ( 95% CI 4% to 9%) relative reduction in risk of AOM episodes. Another 7-valent PCV with the outer membrane protein complex of Neisseria meningitidis (N. meningitidis) serogroup B as carrier protein, administered in infancy, did not reduce overall AOM episodes, while an 11-valent PCV with Haemophilus influenza e (H. influenza e) protein D as carrier protein was associated with a relative reduction in risk of AOM episodes of 34% (95% CI 21% to 44%). 9-valent PCV (with CRM197 carrier protein) administered in healthy toddlers was associated with a 17% ( 95% CI -2% to 33%) relative reduction in risk of OM episodes. CRM197-PCV7 followed by 23-valent pneumococcal polysaccharide vaccination administered after infancy in older children with a history of AOM showed no beneficial effect on further AOM episodes. Authors' conclusions Based on current evidence of the effectiveness of PCVs for the prevention of AOM, the currently licensed 7-valent PCV administered during infancy has marginal beneficial effects. Discrete reductions of 6% to 7% may mean substantial reductions from a public health perspective. Administering PCV7 in older children with a history of AOM appears to have no benefit in preventing further episodes.