Infections such as measles, mumps and rubella are more severe in adults than in children. Therefore, there is some concern that adults might be at risk if immunity from childhood vaccination wears off. Natural infections with measles, mumps and rubella do induce lifelong immunity. Vaccination also produces very long-lasting immunity. Immune memory resulting from vaccination seems to persist even if there is no antibody detectable in the blood. The occurrence rate of measles, mumps and rubella among those who were the first to be vaccinated has not been affected by the passage of time. Diphtheria and tetanus are somewhat different. Protection against these diseases requires the actual presence of antibody in the blood at the time a person is exposed to the toxin. Even though immune memory lasts 40 years or more after vaccination, antibody levels decrease over time. These infectious toxins are so potent that disease can occur before the immune system has time to respond. Adults must receive boosters every 10 years to be protected against diphtheria and tetanus.

This document was published by the Canadian Paediatric society, 1997.

Posted by the Canadian Paediatric Society, July 1997.

---