TY - JOUR
T1 - Short-lived immunity against pertussis, age-specific routes of transmission, and the utility of a teenage booster vaccine
AU - Lavine, Jennie S.
AU - Bjørnstad, Ottar N.
AU - de Blasio, Birgitte Freiesleben
AU - Storsaeter, Jann
N1 - Funding Information:
We thank Inger Cappelen, Venelina Kostova, Synne Sandbu, and Audun Aase at the Folkehelseinstituttet in Oslo for supplying the data and providing comments on the manuscript. This work was supported by funding from the Norwegian Research Council (BFB: Projects 166056/V50 ) the RAPIDD program of the Science and Technology Directorate, Department of Homeland Security , and the Fogarty International Center, National Institutes of Health (ONB) and a grant from the Bill and Melinda Gates Foundation (ONB).
PY - 2012/1/11
Y1 - 2012/1/11
N2 - 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.
AB - 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.
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U2 - 10.1016/j.vaccine.2011.11.065
DO - 10.1016/j.vaccine.2011.11.065
M3 - Article
C2 - 22119924
AN - SCOPUS:84355166192
SN - 0264-410X
VL - 30
SP - 544
EP - 551
JO - Vaccine
JF - Vaccine
IS - 3
ER -
