CDC Emerging Infectious Diseases

The effects of whole-cell pertussis vaccine wane after 5 to 10 years, and infection in a vaccinated person causes nonspecific symptoms (3–7). Vaccinated adolescents and adults may serve as reservoirs for silent infection and become potential transmitters to unprotected infants (3–11). The whole-cell vaccine for pertussis is protective only against clinical disease, not against infection (15–17). Therefore, even young, recently vaccinated children may serve as reservoirs and potential transmitters of infection.

We found that immunity does not even persist into early childhood in some cases. We also observed that DPT vaccine does not fully protect children against the level of clinical disease defined by WHO. Our results indicate that children ages 5-6 years and possibly younger, ages 2-3 years, play a role as silent reservoirs in the transmission of pertussis in the community. Read Study…