BACKGROUND: Pertussis incidence has been increasing for the past two decades in Norway, as in much of the highly vaccinated world. The greatest increase is in teenagers, although the most severe cases occur in infants. A teenage booster is recommended globally, largely with the aim of reducing infant incidence. However few countries have implemented the booster, and almost no data have been published on its utility in preventing infant cases. We aim to assess the duration of vaccine-induced immunity, and the possibility for a teenage-booster vaccine to protect infants in Norway. METHODS AND FINDINGS: We used a unique data set that merged case reports with a national vaccine registry from Norway, 1996-2010, to assess age- and cohort-specific hazards of infection. We also developed and implemented a likelihood-based method for estimating the duration of immunity, taking into account age-contact data relevant for pertussis transmission. The risk of infection in thirteen-year olds increased nearly four-fold, however the hazard in infants did not significantly change. The seasonality of cases in pre-school-aged children differed from that of school-aged children. The introduction of a childhood booster vaccine provided indirect protection for unvaccinated members of the cohort, but little protection to neighboring cohorts. Additionally, we found evidence for increasingly rapid infection after three doses of vaccine, potentially caused by significant and heterogeneous loss of immunity. An estimated 15% of vaccinated individuals lost their immunity within five years after vaccination. CONCLUSIONS: Immunity induced by the acellular pertussis vaccine prevents both disease and transmission, but is short-lived and heterogeneous. The age-mixing patterns lead to little contact between teenagers and infants. Therefore, while a teenage booster vaccine campaign would likely provide strong protection for cohorts of teenagers, it would provide little protection for infants.
BACKGROUND: Pertussis incidence has been increasing for the past two decades in Norway, as in much of the highly vaccinated world. The greatest increase is in teenagers, although the most severe cases occur in infants. A teenage booster is recommended globally, largely with the aim of reducing infant incidence. However few countries have implemented the booster, and almost no data have been published on its utility in preventing infant cases. We aim to assess the duration of vaccine-induced immunity, and the possibility for a teenage-booster vaccine to protect infants in Norway. METHODS AND FINDINGS: We used a unique data set that merged case reports with a national vaccine registry from Norway, 1996-2010, to assess age- and cohort-specific hazards of infection. We also developed and implemented a likelihood-based method for estimating the duration of immunity, taking into account age-contact data relevant for pertussis transmission. The risk of infection in thirteen-year olds increased nearly four-fold, however the hazard in infants did not significantly change. The seasonality of cases in pre-school-aged children differed from that of school-aged children. The introduction of a childhood booster vaccine provided indirect protection for unvaccinated members of the cohort, but little protection to neighboring cohorts. Additionally, we found evidence for increasingly rapid infection after three doses of vaccine, potentially caused by significant and heterogeneous loss of immunity. An estimated 15% of vaccinated individuals lost their immunity within five years after vaccination. CONCLUSIONS: Immunity induced by the acellular pertussis vaccine prevents both disease and transmission, but is short-lived and heterogeneous. The age-mixing patterns lead to little contact between teenagers and infants. Therefore, while a teenage booster vaccine campaign would likely provide strong protection for cohorts of teenagers, it would provide little protection for infants.
Authors: S Salmaso; P Mastrantonio; S G Wassilak; M Giuliano; A Anemona; A Giammanco; A E Tozzi; M L Ciofi degli Atti; D Greco Journal: Vaccine Date: 1998-08 Impact factor: 3.641
Authors: F Simondon; M P Preziosi; A Yam; C T Kane; L Chabirand; I Iteman; G Sanden; S Mboup; A Hoffenbach; K Knudsen; N Guiso; S Wassilak; M Cadoz Journal: Vaccine Date: 1997-10 Impact factor: 3.641
Authors: Kristine M Bisgard; F Brian Pascual; Kristen R Ehresmann; Claudia A Miller; Christy Cianfrini; Charles E Jennings; Catherine A Rebmann; Julie Gabel; Stephanie L Schauer; Susan M Lett Journal: Pediatr Infect Dis J Date: 2004-11 Impact factor: 2.129
Authors: Abdolreza Advani; Hans O Hallander; Tine Dalby; Karen Angeliki Krogfelt; Nicole Guiso; Elisabeth Njamkepo; Carl Heinz Wirsing von Könnig; Marion Riffelmann; Frits R Mooi; Per Sandven; Anna Lutynska; Norman K Fry; Jussi Mertsola; Qiushui He Journal: J Clin Microbiol Date: 2012-11-21 Impact factor: 5.948
Authors: Didrik F Vestrheim; Martin Steinbakk; Martha L Bjørnstad; Amir Moghaddam; Nils Reinton; Mette L Dahl; Nils Grude; Per Sandven Journal: J Clin Microbiol Date: 2012-10-03 Impact factor: 5.948
Authors: Erinn Sanstead; Cynthia Kenyon; Seth Rowley; Eva Enns; Claudia Miller; Kristen Ehresmann; Shalini Kulasingam Journal: Am J Public Health Date: 2015-07-16 Impact factor: 9.308
Authors: A Wensley; G J Hughes; H Campbell; G Amirthalingam; N Andrews; N Young; L Coole Journal: Epidemiol Infect Date: 2017-01-09 Impact factor: 4.434