Is everyone protected from disease by immunisation?
Even when all the doses of a vaccine have been given, not everyone is protected against the disease. Measles, mumps, rubella, tetanus, polio and Hib vaccines protect more than 95% of children who have completed the course. One dose of meningococcal C vaccine at 12 months protects over 90% of children. Three doses of whooping cough (pertussis) vaccine protects about 85% of children who have been immunised, and will reduce the severity of the disease in the other 15% if they do catch whooping cough. The protection levels provided by vaccines differ. For example, if 100 children are vaccinated with MMR, 5-10 of the fully immunised children might still catch measles, mumps or rubella (although the disease will often be milder in immunised children). However, if you do not immunise 100 children with MMR vaccine, and the children are exposed to measles, most of them will catch the disease with a high risk of complications like lung infection (pneumonia) or inflammation of the brain (encephal
