A Cochrane review ¹ included 6 efficacy trials with a total of 46,283 participants and 52 safety trials with a total of 136,541 participants. Meta-analysis was not possible. 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 are 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.

Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions and variability in results across studies).