TORONTO — Health Canada has approved a vaccine that helps prevent painful shingles outbreaks in older people who had chickenpox earlier in life.

Zostavax is made by Merck Frosst Canada and should be available through doctors and pharmacies starting sometime next year.

The virus that causes chickenpox remains in a portion of the nervous system after infection, lying dormant for years and sometimes indefinitely.

But later in life the virus can reactivate, causing an outbreak of shingles.

The disease starts with a painful skin rash that can clear up within a couple of weeks, but can also leave a legacy of pain that lasts for months and even years.

Merck has not yet said how much the vaccine will sell for in Canada.