Fig 1.
Timeline of household and contact eligibility and implementation of study procedures.
a. Top, household eligibility based on day that the index case is reported relative to the day of index case cough onset. Bottom, household or individual household contact eligibility based on day of onset of acute cough illness in a household contact relative to day of cough onset in the index case. If any household contact had acute cough illness or pertussis diagnosis with illness onset 7 to 28 days prior to cough onset in the index case, the household is ineligible. If a household contact had acute cough illness with one or more other pertussis symptom and/or a diagnosis of pertussis with onset between 7 days prior to cough onset in the index case and the time of the first study interview, the contact is ineligible but other contacts in the household remain eligible to participate. b. Timing of the two study interviews relative to the day the index case was reported to the health department.
Fig 2.
Household contact eligibility, enrollment, and study participation among contacts identified within the 180 initially enrolled households.
NP, nasopharyngeal.
Table 1.
Index case and household contact characteristics.
Table 2.
Pertussis symptoms and positive or indeterminate nasopharyngeal swab or serologic results among household contacts of pertussis cases, by receipt of post-exposure prophylaxis (PEP).
Fig 3.
Timing of key events for the five household contacts with positive PCR or culture for B. pertussis on nasopharyngeal swabs.
Contacts a and d were asymptomatic at all study interviews in which they participated. NP, nasopharyngeal; PCR, polymerase chain reaction; PEP, post-exposure prophylaxis.