Pertussis: a persistent cause of morbidity and mortality in young infants.

In 2012, a pertussis outbreak in Dallas County resulted in the deaths of 4 children (3, unvaccinated; 2, <60 days of age). Despite recommendations that include immunization of women preferably during the third trimester of pregnancy or postpartum, household contacts ("cocooning"), and infants as early as 42 days of age, challenges in pertussis prevention remain.