Victoria, Seychelles — The Seychelles’ Ministry of Health on Friday began a vaccination campaign against yellow fever, a response to an epidemic in mainland Africa, says a top official.

The campaign will last for three months. An estimated 55,000 Seychellois — a little over half of the Seychelles’ population — will be vaccinated during that period.

“Seychelles has never recorded any case of yellow fever but with climate change, and the mosquito types that we have anything is possible,” said Public Health Commissioner Dr. Jude Gedeon.

Gedeon said the Ministry of Health decided to carry out the programme following the World Health Organisation’s guideline that a yellow fever vaccine can provide lifelong protection.

Yellow fever virus is spread by the bite of an infected female mosquito. An infected person will have symptoms like fever, chills, loss of appetite and nausea, muscle pains, which usually improve within five days.

In some cases, the fever returns and can damage the liver, which in turn causes bleeding and kidney problems.

“Yellow fever can be fatal, and the virus is considered to be the most severe among mosquito-borne diseases. It is more severe than dengue, chikungunya and even the recent zika virus, so people need to protect themselves,” said Gedeon.

The Yellow fever vaccine has been part of children’s vaccination programs since 1995. Anyone over the age of 20 may not have received the vaccine. Before 1995 residents of Seychelles, an archipelago in the western Indian Ocean, were only vaccinated when travelling to high-risk countries.

Gedeon said the vaccine will not be administered to people over 60 as it may cause adverse side effects. He is, however, encouraging those between 21 and 59 to take part in the exercise.

The vaccine becomes effective 10 days after being administered and provides life-long protection.

The vaccinations cost around $300,000 (3.9 million Seychelles’ rupees) and is financed by the Seychelles’ government. It is being administered free of charge to Seychellois.

The vaccine is currently being administered to inhabitants on La Digue, the third most populated island.

The Ministry of Health will announce when other campaigns on Mahe, the main island, will get underway.