Did two booster doses for schoolchildren change the epidemiology of pertussis in Israel?

Pertussis is the only vaccine-preventable disease that has re-emerged in Israel. In the last two decades, despite high primary immunization coverage, crude incidence increased over tenfold, with especially high morbidity among infants and adolescents and with 19 infant deaths. Two pertussis vaccine boosters were added, in 2005 for 7-year-olds and in 2011 for 13-year-olds. We reviewed age group incidence from 1999 to 2016, before and after the booster program introduction. We compared three groups of 13-15 year-olds with identical primary immunization but different booster immunization histories. Vaccine effectiveness was calculated before and after adjustment for specific incidence in those aged 65 and over. Two years after one booster, adjusted vaccine effectiveness was 74.5%. Two years after two boosters, adjusted vaccine effectiveness was 91.8%. However, crude morbidity rates were not reduced. The booster program has been effective only among recipient groups. The program will be continued. Israel is now encouraging pregnant women to be vaccinated against pertussis to improve protection of infants. [ABSTRACT FROM AUTHOR]