The polio vaccine is one of the primary childhood vaccinations. It is given at two, four, and six months in conjunction with the diphtheria, tetanus, whooping cough and HIB vaccines.
These are given by injection while the polio vaccine is given orally in droplet form. A booster dose is usually given before the child starts primary school.
Polio is a live vaccine, containing three different strains of the virus. It was introduced in 1962 and resulted in a huge drop in the number of cases of poliomyelitis.
Polio infection dropped by a factor of 100 in the UK between 1955 and 1975 as a result of vaccination.
The vaccine works by introducing polio virus into the intestine. It promotes antibody formation both in the gut and in the bloodstream, so that the immune system is primed to resist any subsequent infection by natural polio virus.
Polio attacks the nervous system and can cause permanent paralysis in the arm or leg muscles. If it affects the chest muscles, it can kill.
Natural polio is highly infectious. Households with young children can have infection rates of 100 per cent.
Polio is transmitted by both oral secretions and faecal material. While infection may produce no symptoms, it can range in severity from a simple fever to meningitis and severe muscle paralysis.