2012 Antigen Review for the New Zealand National Immunisation Schedule: Pertussis

Abstract

Despite widespread gains in disease control with vaccination programmes, pertussis remains a major global public health problem. Pertussis is a disease that occurs across the age spectrum. Young infants remain at risk of serious disease which continues to cause fatalities in both developed and developing countries. The primary focus of pertussis vaccination policy internationally is to reduce the risk of severe pertussis in infants. This requires both a complete and timely delivery of the primary immunisation series and the appropriate use of booster doses of pertussis vaccine. The worldwide priority is to achieve greater than 90 per cent coverage for the primary infant series of three doses with a high quality pertussis vaccine in infants. Universal implementation of infant immunisation has reduced the number of infant deaths and the incidence of pertussis disease in younger children. The contribution that older age groups make to the spread of pertussis to infants has been increasingly recognised in recent decades and has become a key consideration in contemporary refinements of national and international immunisation recommendations. Whole-cell pertussis vaccines have been in use since the 1940s. Their effectiveness is shown by the 150 to 200 fold decrease in incidence rate of pertussis seen in the United States between the 1940s and the 1970s. While effective, they are among the more reactogenic of vaccines and have never been considered appropriate for use in older children and adults. Since the 1990s many countries have moved to using acellular pertussis vaccines which have better reactogenicity profiles than whole cell pertussis vaccines and can be used across the age range. The most efficacious acellular vaccines are, at best, only as efficacious as the most efficacious whole-cell vaccines. Duration of vaccine induced immunity from acellular pertussis vaccines appears to be shorter than what was achieved when immunisation schedules consisted solely of whole-cell vaccines. There is considerable concern that immunisation schedules which consist solely of acellular pertussis vaccine are less effective at controlling pertussis than were whole cell vaccine schedules. Natural immunity to pertussis is incomplete and hence pertussis is a recurrent disease in humans. Our incomplete understanding of the pathogenesis and immunology of Bordetella pertussis infection and pertussis disease continues to limit our capacity to develop vaccines that provide sustained protection against disease or effective prevention of transmission of B. pertussis.