People in their 70s are offered a vaccination on the NHS to protect against shingles.
Shingles is an infection caused by the same virus that causes chickenpox, the herpes varicella-zoster virus. It results in a rash that can be mildly itchy to intensely painful.
There's also the risk of long-term nerve pain, called post-herpetic neuralgia.
The shingles vaccine
The vaccine, called Zostavax, is given as a single injection under the skin (subcutaneously). It can be given at any time in the year. Unlike with the flu jab, annual injections are not needed.
The vaccine has been tested for safety in clinical trials.
In rare cases there may be an allergic reaction to the vaccine and one of its components, neomycin. This includes skin rash or contact dermatitis.
Shingles and ageing
Elderly people are at particular risk of shingles. The Department of Health says the vaccination programme will prevent 38% of the 30,000 cases seen every year in people over 70.
A large US study involving more than 760,000 people aged 65 and over found vaccination halved the chances of developing shingles.
The study published in PLoS Medicine found than without the jab, 10 in 1,000 people a year would develop shingles. After vaccination, that fell to five in 1,000.
Even if the vaccine doesn't stop a person developing shingles, a 55% reduction in symptoms is possible.
The Shingles Support Society is campaigning for shingles vaccination to begin earlier, at 60. The charity says this is because shingles can occur at any age.
The vaccine is licensed in Europe for adults over 50.