Liberia has released its last confirmed Ebola patient, with no new cases reported for more than a week, just as neighboring Guinea is gearing up for vaccine trials to begin Saturday.
A Chinese-run Ebola treatment center in the Liberian capital, Monrovia, released Beatrice Yardolo on Thursday. She told the Associated Press she is "one of the happiest persons on Earth today."
The World Health Organization said Liberia, for the first time since last May, reported no new confirmed cases last week. The country must complete 42 days with no new cases reported – twice the standard length of quarantine – before it can be declared Ebola-free.
Meanwhile, the number of new Ebola cases in Sierra Leone and Guinea has increased. Guinea reported 51 new confirmed cases last week, with Sierra Leone reporting 81.
WHO officials said the numbers suggest the need for isolating and treating Ebola patients is not yet understood, accepted or acted upon in those countries.
Final-stage testing to begin
In related news, the WHO, the United Nations’ health agency, said it will carry out the final stage of testing an experimental Ebola vaccine in Guinea later this week.
The agency issued a news release Thursday saying it will begin vaccinations Saturday in Basse Guinee, an area including the capital, Conakry, and surrounding prefectures. It currently has the most Ebola cases in the West African country.
"If a vaccine is found effective, it will be the first preventive tool against Ebola in history," said WHO Director-General Margaret Chan.
More than 23,900 confirmed and suspected cases of Ebola have been reported since the outbreak began in December 2013, including some 9,800 deaths. Nearly 500 health workers have been among the dead in the worst Ebola epidemic ever.
But recent steep declines in new Ebola cases will make it far harder to prove whether experimental vaccines work, as the vaccine's effect will be difficult to establish.
The WHO, however, said it was committed to pushing ahead.
"The Ebola epidemic shows signs of receding but we cannot let down our guard until we reach zero cases," said Marie-Paule Kieny, head of the WHO's Ebola research and development effort.
"An effective vaccine to control current flare-ups could be the game-changer to finally end this epidemic and an insurance policy for any future ones."
Health workers will vaccinate people who have had contact with someone recently diagnosed with Ebola, a strategy known as "ring vaccination" which was used to eradicate smallpox in the 1970s.
The VSV-EBOV vaccine was developed by Canada’s Public Health Agency and licensed to NewLink Genetics, a U.S. company in Iowa that is collaborating with the pharmaceutical firm Merck & Co. Another promising vaccine, cAd3-ZEBOV, was developed by GlaxoSmithKline PLC with support from the U.S. National Institutes of Health.
All three worst-hit countries – Guinea, Liberia and Sierra Leone – aim to conduct final-stage trials of vaccines. Liberia already testing is the GlaxoSmithKline and Merck-NewLink shots, while Sierra Leone is expected to announce plans soon.