People in their 70s across the UK will be offered a vaccine against shingles from this week.
The government-led programme will initially offer the vaccine to those aged 70 and 79.
Shingles, or herpes zoster, is an infection of a nerve and the area of skin around it, and can cause a painful rash.
Around 800,000 people will be eligible for the vaccine in the first year of the programme.
In England, Scotland, Wales and Northern Ireland, those aged 70 and 79 will initially be invited to take up the vaccination.
Over the next few years, the programme will expand to include more of the 70-to-79 age group across the UK until it is fully covered.
After that, the jab should only need to be offered to people as they reach their 70th birthdays.
Shingles is caused by the same virus that causes chickenpox. Around 14,000 people develop it each year.
After someone has had chickenpox most of the virus is destroyed but some survives and lies inactive in the body in the nervous system.
It can then be reactivated later in life when the immune system is weakened by increasing age, stress or treatments that affect immunity.
In severe cases it can cause complications such as hearing loss or brain swelling.
Shingles is most common in the over-70s.
Someone who has not had chickenpox can catch it from someone with shingles - but it is not possible to catch shingles itself from someone with the condition.
Dr Paul Cosford, director for health protection and medical director at Public Health England, said having the vaccine would reduce the chances of having shingles by a third.
Health minister Lord Howe said: "Shingles can be a nasty disease for older people and can lead to long-term health problems for around 14,000 people each year.
"This new vaccine can prevent some of the most serious cases, giving people the chance to live without the discomfort and pain that shingles causes."