Canada has approved a vaccine to prevent Ebola in non-pregnant and otherwise healthy adults aged 18 and older.

The Public Health Agency of Canada (PHAC) says the single-dose Ervebo vaccine should be offered to persons who have been exposed to the Ebola virus in Canada.

The agency says the shot is not meant for routine immunization, nor for vaccination before travel.

It adds that it may be considered for use in pregnant or immunocompromised people who have been exposed to the virus in a lab or health-care setting, or to infants and children after exposure.

PHAC says the vaccine may also be used in exceptional situations when a team of health-care workers expects to directly care for people with confirmed symptoms, which include diarrhea, vomiting, fever and internal bleeding.

The highly infectious disease starts with flu-like symptoms after contact with bodily fluids such as blood and saliva and has infected people in several African countries since the 1970s.

While a small number of cases outside Africa have been reported in the last two decades, none have been diagnosed in Canada.

Patients are isolated to prevent spread and given fluids to prevent dehydration but there is no cure.

PHAC says the risk of exposure in Canada is "very low" but those working in labs or health-care settings are at higher risk, especially if there are breaches in infection prevention and control measures.

The United States approved Ervebo in 2019, and at least one case has been reported there since then.

The Merck vaccine has also been approved in some African countries.