Int J Infect Dis 1997; 1(3):148-151.

This study was undertaken to assess the safety and protective efficacy against pertussis of a monocomponent pertussis toxoid vaccine in a society with hyperendemic pertussis. A total of 3450 healthy infants from child health centers in the Gšteborg area of Sweden were enrolled in a double-blind, randomized, placebo-controlled study. A combined diphtheria-tetanus vaccine was given with or without pertussis toxoid (DTP-toxoids vs DT-toxoids) at 3, 5, and 12 months of age. One week after each vaccination a telephone interview about reactions was performed. From the day of the first vaccination a nasopharyngeal culture and acute and convalescent sera were obtained from study children and family members with cough lasting 7 or more days. Coughing episodes were classified according to the World Health Organization (WHO) definition of pertussis. There were no serious reactions. There were slightly more local reactions with DTP-toxoids than with DT-toxoids. During the period of blinded follow-up, which began from 30 days after the third vaccination and lasted on average for 17.5 months, the general vaccine efficacy was 71% (95% confidence interval (CI), 63-78%), and during an extended period of open follow-up performed during 6 months, vaccine efficacy was 77% (95% CI, 65-85%). The efficacy against household exposure during the same periods was 73% (95% CI, 61-83%) and 76% (95% CI, 51-91%), respectively. A hydrogen-peroxide inactivated pertussis toxoid vaccine that is easily standardized is safe and confers substantial protection against pertussis.

Key Words: efficacy, pertussis, toxoid, vaccine

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