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Public health authorities said Friday they hoped to begin trials of Ebola vaccines in disease-ravaged West Africa as early as December and could know around April whether they were effective, clearing the way for possible mass inoculations to stem the epidemic.
“Vaccine is not the magic bullet,” Dr. Marie-Paule Kieny of the World Health Organization said at a news conference in Geneva. “But when ready, they may be a good part of the effort to turn the tide of this epidemic.”
Dr. Kieny, assistant director-general for health systems and innovation for the Geneva-based organization, spoke Friday about the conclusions of a meeting the day before at which government officials, drug companies and others discussed how best to test and possibly deploy vaccines.
Trials in December would be a month earlier than Dr. Kieny had indicated earlier this week. Manufacturers have committed to having millions of vaccine doses available in 2015, with hundreds of thousands ready by the first half of the year, she said.
“All previous plans are changing from week to week, and always to a greater involvement and a greater mobilization of all efforts to have more vaccine available more quickly,” Dr. Kieny said.
Some health experts say that an effective vaccine might now represent the best hope because it has been difficult to slow the spread of disease using only conventional public health measures like isolating patients and tracing their contacts. However, efforts are being made to intensify those conventional methods, such as by building new treatment centers to handle more patients.
Dr. Kieny said a decision to start mass vaccinations later in 2015 would depend on whether one or more vaccines proved safe and effective, whether there would be enough vaccine available and whether that strategy would be needed.
Two experimental vaccines are already being tested for safety in healthy volunteers in the United States and other countries outside the outbreak region. One is being developed by the National Institutes of Health andGlaxoSmithKline and the other by the Canadian government and NewLink Genetics.
At least five other vaccines could enter human testing in the first few months of 2015, Dr. Kieny said.
If the two most advanced vaccines prove safe in initial testing, trials would begin in Liberia and Sierra Leone to see if the vaccines can actually prevent people from getting Ebola.
Dr. Kieny’s announcement was light on details of the trials, which she said are still subject to change. But what she said was consistent with plans discussed Thursday by a United States government official who requested anonymity.
Participants in the trials would include health care workers, who are at high risk of getting infected. But a trial in Liberia is also likely to include others at high risk, such as burial workers or family members caring for those with Ebola.
The study in Liberia would randomize volunteers to receive either the Glaxo vaccine, or the NewLink vaccine, or a vaccine for some other disease — essentially a placebo in terms of preventing Ebola. About 9,000 volunteers would participate in each of the three arms of the study, the federal official said.
In the Sierra Leone trial, everyone at a particular site, such as a treatment center, would be offered vaccination. But different centers would receive the vaccines at different times, allowing comparison of disease rates between sites where patients were vaccinated earlier and those vaccinated later. In that trial no one would receive a placebo.
That trial, being planned by the Centers for Disease Control and Prevention, is expected to test the Glaxo vaccine but might be expanded to include others.
Dr. Kieny said that at some point there would also be a trial in Guinea, the third of the three countries most affected by the outbreak. But it is not clear yet what that trial would be.
Some critics have said it would be unethical to offer health care workers treating Ebola patients a placebo. But others have argued that since it is not known whether the vaccine works, there is no advantage of getting the vaccine instead of the placebo.
“If you knew the vaccine works, I absolutely agree it’s unethical to randomize,” said Dr. Ripley Ballou, who heads the Ebola vaccine effort at GlaxoSmithKline.
He said a randomized trial against a placebo “gets a definitive answer as quickly as possible” about whether a vaccine is effective, which would be in the best interest of the community as a whole. After that, he said, the vaccine could be made more widely available.
The meeting Thursday also discussed how to pay for the trials and possible vaccine deployment. Dr. Kieny said money could come from donor countries like the United States and Britain, from the World Bank and others.
“We haven’t talked about figures for the time being but there is a broad understanding that money will not be an issue,” she said.
Dr. Kieny said that discussions were also underway about indemnifying vaccine manufacturers, because the vaccines would be deployed with much less than the usual testing. That might be a fund to compensate people who suffer side effects from a vaccine, so that manufacturers would not bear that financial risk.
Conducting the trials in West African countries already devastated by the disease and with poor infrastructure could be a challenge. The vaccines need to be stored at minus 80 degrees Celsius, requiring special freezers.
Dr. Paul Stoffels, the chief scientific officer of Johnson & Johnson, who attended the meeting, said representatives of the affected countries told the participants that it would be hard for health care workers to do the administrative and record-keeping chores associated with a clinical trial.
“They say please come with the capabilities to do it because the people taking care of the patients today can’t do it; they don’t have the time,” Dr. Stoffels said.