Abstract Objective: To assess the protective effect of exclusive breastfeeding and the effectiveness of maternal vaccination in reducing pertussis-like illness. Method: This was a case-control study conducted in sentinel hospitals for pertussis in Recife between July 2016 and July 2018. Cases included children aged under six months with symptoms compatible with pertussis (pertussis-like illness). Controls included children aged under six months, living in the metropolitan region of Recife with no diagnosis of pertussis-like illness and matched by the same hospital and birth date. Results: Seventy-three cases and 194 controls were included. The diagnosis of pertussis-like illness was predominantly clinical (97,2%). Amongst the main symptoms, paroxysmal cough was observed in 95.89% of cases and vomiting in 53.4%. There were 29 hospitalized cases and no deaths. Out of the 73 cases, 47 were born to mothers vaccinated against pertussis during pregnancy, and the mothers of 144 of the 194 controls had been vaccinated. The protective effect of breastfeeding was of 74% (95% CI;38%, 89%). Children younger than six months, who were exclusively breastfed and with mothers vaccinated against pertussis during pregnancy were 5 times less likely to develop pertussis-like illness, corresponding to a protection of 79% (95% CI;31%, 94%). The effectiveness of maternal vaccination against pertussis-like illness in children under six months was low (27%) and not statistically significant (CI 95%; −34% a 60%). Conclusions: Exclusive breastfeeding protects children under six months from pertussis-like illness and may be enhanced when associated with maternal vaccination. These strategies should be encouraged because they also protect against pertussis-like illnesses.

Objective:This study was aimed to evaluate the prevalence of pertussis in adolescents and adults with cough lasting more than 14 days and less than 30 days.Methods:This is a prospective observational study in interepidemic period of pertusis. Ten public health outpatient clinics in the city of Recife, Brazil, were randomly selected for the study. The study population consisted of individuals aged 10 years and over with cough that had lasted between 14 and 30 days. Nasopharyngeal swabs were collected for culture and PCR in order to identify Bordetella pertussis. We adopted the Centers for Disease Control and Prevention in the US (CDC) definition of cases of pertussis.Results:A total of 192 individuals were identified as suspected cases. Their mean age was 40.7 years. Pertussis was confirmed in 10 of the 192 suspected cases, with an estimated prevalence of 5.21% (95% confidence interval 2.03-8.38). All cases met the clinical case definition for pertussis; one suspect had both culture and PCR positive. PCR confirmed 100% of the cases, 7/10 by PCR and 3/10 by epidemiological linkage with a case confirmed by PCR.Conclusion:During an interepidemic period, 1 in 20 cases of prolonged cough had pertussis, suggesting this is an important cause of prolonged cough in adolescents and adults.