Acellular vaccines for preventing whooping cough in children

Background Routine use of whole-cell pertussis vaccines was suspended in some countries in the 1970s/1980s because of concerns about adverse effects. There was a resurgence of whooping cough. Acellular pertussis vaccines (containing purified or recombinant Bordetella pertussis antigens) were developed in the hope that they would be as effective but less reactogenic than the whole-cell vaccines. Objectives To assess the efficacy and safety of acellular pertussis vaccines in children. Search strategy We searched the Cochrane Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2) which contains the Acute Respiratory Infections Group's Specialised Register; MEDLINE (1950 to April week 2 2009) and EMBASE (1974 to April 2009). Selection criteria Double-blind randomised efficacy and safety trials of acellular pertussis vaccines in children up to six years old, with active follow-up of participants and laboratory verification of pertussis cases. Data collection and analysis Two review authors independently performed data extraction and study quality assessment. Differences in trial design precluded pooling of the efficacy data. The safety data from individual trials were pooled using the Cochrane statistical package Review Manager 5. Main results Six efficacy trials and 52 safety trials were included. The efficacy of multi-component (>= 3) vaccines varied from 84% to 85% in preventing typical whooping cough, and from 71% to 78% in preventing mild pertussis disease. In contrast, the efficacy of one-and two-component vaccines varied from 59% to 75% against typical whooping cough, and from 13% to 54% against mild pertussis disease. Multi-component acellular vaccines is more effective than low-efficacy whole-cell vaccines, but may be less effective than the highest-efficacy whole-cell vaccines. Most systemic and local adverse events were significantly less common with acellular than with whole-cell pertussis vaccines for the primary series as well as for the booster dose. Authors' conclusions Multi-component acellular pertussis vaccines are effective, and show less adverse effects than whole-cell pertussis vaccines for the primary series as well as for booster doses.