Public health authorities may be facing a situation similar to that of polio, where vaccinated individuals can still transmit infection.
Asymptomatic transmission and the resurgence of Bordetella pertussis
Benjamin M. Althouse and Samuel V. Scarpino BioMed Central Medicine, 2015; DOI 10.1186/s12916-015-0382-8
Although a clear role for the previously suggested mechanisms still exists, asymptomatic transmission is the most parsimonious explanation for many of the observations surrounding the resurgence of B. pertussis in the US and UK. These results have important implications for B. pertussis vaccination policy and present a complicated scenario for achieving herd immunity and B. pertussis eradication.