Orenstein等人在给杂志编辑的信中指出Halperin等在Nova Scotia百日咳研究的报告中,不全面地评价了百日咳菌苗的效力,并且低估了实际的效力。菌苗的效力(VE)定义如下:VE(%)=[(ARU-ARV)/ARU)×100(1),ARU是未接种人群的发病率,ARV是接种人群的发病率。Halperin等使用筛选法来估计菌苗的效力,它是由上述公式推导出来的:VE(%)=[(PPV-PCV)/PPV(1-PCV)]×100(2),PPV是人群接种的百分比, Orenstein et al., In a letter to the journal editor, pointed out Halperin et al. Did not fully evaluate the efficacy of pertussis vaccine in the report of the Nova Scotia pertussis study and underestimated the actual efficacy. The efficacy of the vaccine (VE) is defined as follows: VE (%) = [(ARU-ARV) / ARU) × 100 (1). ARU is the incidence of unvaccinated populations and ARV is the incidence of vaccinated populations. Halperin et al. Used the screening method to estimate the efficacy of the vaccine and was derived from the above formula: VE (%) = [(PPV-PCV) / PPV (1-PCV)] x 100 Of the percentage,