Effectiveness of Maternal Immunization With Boostrix at Preventing Pertussis Among Infants <2 Months Old in the United States

Infant subjects of at least 2 days old and less than (<) 2 months old, who met the pertussis diagnosis definition (laboratory confirmed pertussis, epidemiological linkage to a laboratory-confirmed case, clinically compatible illness), and who met the case infants inclusion criteria (resided in the catchment area on their cough onset date, were born in a hospital in their state of residence, had at least 37 weeks gestational age at birth, were neither adopted, nor in foster care and did not live in a residential care facility).

This post-hoc analysis was limited to cases and controls whose mothers were either vaccinated with Boostrix or did not receive any Tdap vaccine. Cases with no remaining matched control were also excluded from the analysis and vice versa.

Infant subjects of at least 2 days old and less than (<) 2 months old, who did not have a pertussis diagnosis prior to the cough onset date and who met the inclusion criteria for control infants (were born on a hospital in their state of residence, were at least 37 weeks gestational age at birth, were neither adopted, nor in foster care, did not live in a residential care facility, were born at the same hospital as the case infant).

This post-hoc analysis was limited to cases and controls whose mothers were either vaccinated with Boostrix or did not receive any Tdap vaccine. Cases with no remaining matched control were also excluded from the analysis and vice versa.