Pertussis antibodies, protection, and vaccine efficacy after household exposure
J. Storsaeter, W. C. Blackwelder and H. O. Hallander
Department of Pediatrics, Karolinska Institute, Sachs' Children's Hospital, Stockholm, Sweden.
During a randomized trial of a cellular pertussis vaccines, significantly
fewer recipients of a two-component vaccine (Japanese National Institute of
Health [JNIH]-6) were diagnosed as primary or coprimary cases in households
than either placebo recipients or those who received a monocomponent
pertussis toxoid vaccine (JNIH-7). After household exposure to a
culture-confirmed primary case, efficacy for JNIH-6 was estimated to be 35%
(95% confidence interval, -14% to 57%) against any culture-confirmed
disease and 58% (95% confidence interval, -6% to 84%) against clinical
disease with 21 days or more of coughing spasms. The corresponding efficacy
estimates for JNIH-7 were 67% (95% confidence interval, 32% to 80%) and 82%
(95% confidence interval, 41% to 96%). Differences between the JNIH-6 and
JNIH-7 vaccines in efficacy after household exposure were not statistically
significant. No association could be established between protection against
pertussis after household exposure and serum levels of IgG antibody to
pertussis toxin or filamentous hemagglutinin in vaccinated individuals, in
either study children or other household members.
