Pertussis in infants in Nordic countries

Aim: A life-course immunisation approach is required to prevent and control pertussis. We aimed at reviewing pertussis incidence among infants in Denmark, Finland, Norway and Sweden, and at putting these data in the context of national surveillance systems and vaccination schedules. Methods: We collected 2014-2018 data on pertussis incidence, on pertussis vaccination schedules and on coverage of the third dose of the diphtheria toxoid, tetanus toxoid and acellular pertussis vaccine from publicly available sources. We gathered opinions on national surveillance systems from public health and paediatrics experts of the relevant countries. Results: The pertussis vaccination schedules and coverage in infancy were similar across countries. All countries except Denmark recommended an additional booster vaccine dose for adolescents. None of the countries had maternal immunisation recommendation. Mean pertussis incidence in Denmark, Sweden and Finland was 168, 76 and 35 per 100,000 infant-years, respectively. Data were insufficient to derive a mean incidence in Norway. There were no systematic differences in the national surveillance systems across the countries. Conclusion: The higher mean pertussis incidence in Denmark may be explained by the lack of recommendations for adolescent pertussis booster vaccination. Further investigations are warranted.