Abstract
The Public Health Agency of Sweden carried out a literature review on diphtheria vaccinations for seronegative people above 6 years of age with an uncertain vaccine history. The aim was to harmonise national Swedish recommendations with the current World Health Organization recommendations. There was no firm conclusion about dosage. Some low-dose vaccines used in the past had suboptimal potency, while others evoked adequate levels of antitoxin after three primary doses. We concluded that low-dose diphtheria vaccines that have been approved by a national medical products agency can be used for primary vaccination against diphtheria for individuals above 6 years of age.