Immunity to Tetanus, Diphtheria and Poliomyelitis in the Adult Population of Sweden in 1991

Background: During 1990 and 1991 a survey of immunity was carried out in Sweden. The main purpose was to estimate the level of immunity to diphtheria, tetanus and polio in the adult population. In total, 4800 people, randomly selected according to a stratified, two-stage, sampling plan, were contacted and asked to contribute a blood sample. Of those selected, 70.6% gave a blood sample.

Methods: Estimates and confidence intervals of the proportion of the population with antibodies exceeding some titre was calculated. The population was divided according to sex, year of birth (five age groups) and residence (four regions).

Results: In age groups that were born after the introduction of childhood vaccination, > or =90% and 75-90% of people have demonstrable antibodies at a protective level against tetanus and diphtheria respectively. Those born earlier, especially women, are poorly protected with less than 50% having protective antibody levels for both tetanus and diphtheria. Differences between men and women were particularly seen in the age groups born between 1930 and 1950. Less than 5% of the Swedish population lacked the protective level antibodies against polio types 1, 2 and 3 respectively.

Conclusions: Vaccination against tetanus, which can be combined with vaccination against diphtheria, can be recommended especially to women born before 1950 and with no documented previous vaccination. The same recommendation can be given for men born before the 1930s. As regards poliomyelitis, general booster vaccination of the adult population does not appear to be necessary at present.