Ebola
Health workers in November 2015 with Mibemba Soumah, infected by Ebola, at a treatment center in Conakry, Guinea. Credits: New York Times




In a scientific triumph that will change the way the world fights a terrifying killer, an experimental Ebola vaccine tested on humans in the waning days of the West African epidemic has been shown to provide 100 percent protection against the lethal disease.

The vaccine has not yet been approved by any regulatory authority, but it is considered so effective that an emergency stockpile of 300,000 doses has already been created for use should an outbreak flare up again.

Since Ebola was discovered in the former Zaire in 1976, there have been many efforts to create a vaccine. All began with a sense of urgency but then petered out for lack of money. Although only about 1,600 people died of Ebola over those years, the grotesque nature their deaths — copious hemorrhaging from every orifice — has lent the disease a frightening reputation.

Ultimately, only the huge, explosive 2014 outbreak that took 11,000 lives in Africa and spread overseas, reaching a handful of people in Europe and the United States, provided the political and economic drive to make an effective vaccine.

The vaccine was not ready in time to stop the outbreak, which probably began in a hollow, bat-filled tree in Guinea and swept Liberia and Sierra Leone before being defeated. But the prospect of a vaccine stockpile now has brought optimism among public health experts.

“While these compelling results come too late for those who lost their lives during West Africa’s Ebola epidemic, they show that when the next outbreak hits, we will not be defenseless,” said Marie-Paule Kieny, the World Health Organization’s assistant director-general for health systems and innovation and the study’s lead author. “The world can’t afford the confusion and human disaster that came with the last epidemic.”

The vaccine opens up new, faster, more efficient ways to encircle and strangle the virus. The many small Ebola outbreaks that occurred between 1976 and 2014 were all stopped in remote villages by laborious methods: medical teams flew in, isolated the sick, and donned protective gear to treat them and bury the dead.

The new vaccine has some flaws, experts said. It appears to work only against one of the two most common strains of the Ebola virus, and it may not give long-lasting protection. Some of those who get it report side effects like joint pain and headaches.

“It’s certainly good news with regard to any new outbreak — and one will occur somewhere,” said Dr. Anthony S. Fauci, director of the National Institute for Allergy and Infectious Diseases, which makes many vaccines and did some early testing on this one. “But we still need to continue working on Ebola vaccines.”

The Lancet study was done in 11,841 residents of Guinea last year. Among the 5,837 people who got the vaccine, none came down with Ebola 10 or more days later. There were 23 Ebola cases among the thousands of others not immediately vaccinated.

The Ebola trial was led by the World Health Organization, the Guinean Health Ministry, Norway’s Institute of Public Health and other institutions. The vaccine, known as rVSV-ZEBOV, was developed over a decade ago by the Public Health Agency of Canada and the United States Army and is now licensed to Merck.

Its genetic “spine” is that of a vesicular stomatitis virus, which sickens cattle but usually does not infect humans. Spliced into the spine is the gene coding for an Ebola virus surface protein that prompts the immune system to make antibodies.

Tests in monkeys showed that one shot protected all of them when it was given at least a week before they were given a high dose of Ebola. The shot even protected a few monkeys who received it a day after being infected with Ebola.

New York Times







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