Effectiveness of pertussis vaccines for adolescents and adults: case-control study

Authors have concluded that " Tdap vaccination was moderately effective at preventing PCR confirmed pertussis among adolescents and adults". There is a lack of clarity in this statement.

PCR positivity can be of two types: One is merely colonization with asymptomatic infection and another is diseased (pertussis) with colonization. The authors have not done demarcation in the two categories as the former could have antibodies and yet serve as silent reservoirs for transmission (carrier).