By Kate Kelland

LONDON, Dec 5 (Reuters) – – A stockpile of 500,000 doses of Ebola vaccine for emergency use in outbreaks of the deadly fever is being established by the global vaccine alliance GAVI.

The plan is for poor and middle-income countries to access the $178 stockpile free of charge, GAVI said on Thursday, while other countries will need to refund the costs.

The stockpiling will start with Merck’s newly developed Ervebo vaccine, which won regulatory approval last month.

GAVI is a public-private partnership backed by the Bill & Melinda Gates Foundation, the World Health Organization, the World Bank, UNICEF and others, which arranges bulk buys to reduce vaccine costs for poor countries.

The price paid for the Ebola vaccines will be agreed in a tender process led by the U.N. children’s fund UNICEF, GAVI’s procurement agency.

Merck’s Ervebo is the first Ebola vaccine to successfully complete clinical trials and win a marketing license. It target’s the Zaire strain of Ebola – the one that has caused most of the known outbreaks.

It has proven highly effective in clinical trials and in an ongoing epidemic in the Democratic Republic of Congo, where more than 250,000 people have received it since the outbreak started in August 2018.

“The Ebola vaccine has shown extraordinary efficacy in tackling the outbreak in the DRC,” said Seth Berkley, GAVI’s chief executive officer. “Now that funding has been approved, we will get to work with manufacturers and our alliance partners to build the stockpile.”

Another seven potential Ebola vaccine candidates – also designed to target the Zaire strain – are in various phases of development, including a two-dose preventative shot from Johnson & Johnson currently being trialled in Congo.

Berkley said the Ebola stockpile could include these vaccines if and when they passed full clinical testing and gained marketing license.

Jason Nickerson, a humanitarian affairs expert for the international charity Medecins Sans Frontieres, welcomed GAVI’s move, but urged it to allow a “thorough, independent and transparent estimate” of the vaccines’ cost of manufacture to “ensure that the price paid is fair and reasonable”.

GAVI also manages emergency stockpiles of meningitis, cholera and yellow fever vaccines.

(Reporting by Kate Kelland; Editing by Kevin Liffey and Alison Williams)