The New York Times reports: “For this reason, it’s very urgent that we get into the field very quickly to do these clinical trials, because if there are very, very, very few cases of Ebola, as I’m sure you understand, it’s going to be difficult to test whether the vaccines work or not,” Dr. Helen Rees, an adviser to the World Health Organization, said during a news conference on Friday at the organization’s headquarters in Geneva.
Dr. Marie-Paule Kieny, an assistant director general of the W.H.O., said two vaccines had been found safe enough in early testing in countries outside the outbreak zone to justify wider testing in the affected countries. But she said it would take two to four weeks more to determine the proper doses.
She said a clinical trial in Liberia could begin as soon as the end of this month, with studies in Sierra Leone and Guinea starting in February.
Dr. Kieny said it could take up to six months to determine if the vaccines are effective. Production has already begun, so if any of the vaccines proves safe and effective, millions of doses could be quickly made available.
Vaccine effectiveness is determined by how many vaccinated people come down with a disease compared with those who are not vaccinated, or vaccinated later. If few new cases of the disease are occurring, it would be harder to see any difference. Dr. Kieny said plans were being made to increase the size of the trial in Liberia if needed.
In Liberia, there were eight confirmed new cases and 40 probable new cases recorded in the five days ending Jan. 2, down from a peak of 300 confirmed new cases a week in August and September, according to the W.H.O. The number of new cases has been falling in Sierra Leone, but it remains the most heavily affected country. In Guinea, it is not clear if case numbers are falling, the health organization said.
If the epidemic continues to ebb, it may be too late for the vaccines to make a difference in this outbreak. Dr. Rees said that a working group had been formed to discuss how to deploy the vaccines, should they prove safe and effective, but that the situation was changing too rapidly to make such a decision now.
“Hopefully, we will have broken the back of this epidemic by the time we finish these trials,” she said.
Even if that is the case, she and Dr. Kieny said, sporadic cases would most likely occur, and vaccinations might be given to people nearby to protect them and help prevent further spread of the disease — a strategy known as ring vaccination. And it might be wise to vaccinate health workers for long-term protection, they said.
The two vaccines that are most advanced in testing are being developed by GlaxoSmithKline and Merck. The Glaxo vaccine is being developed with theNational Institutes of Health; Merck’s was originally developed by the Public Health Agency of Canada and licensed to a small Iowa company, NewLinkGenetics, which in turn enlisted Merck.
Testing of the Merck vaccine at a hospital in Switzerland was suspended in December after a number of patients developed pain in the joints of their fingers and toes. Testing resumed this week using a lower dose. Dr. Kieny said the pain was generally transient and mild and “not of sufficient concern to stop the development of this vaccine.”
A third vaccine, being developed by Johnson & Johnson, began early safety testing in volunteers this month. That company is also planning tests in West Africa.
There has been debate over how to conduct the studies. Some experts say testing the vaccines against a placebo would be the surest way to determine whether they work. Others counter that it would be unethical to administer a placebo during a deadly epidemic.
The trials will cover all the approaches, with different designs in each country. In Liberia, the Merck and Glaxo vaccines will be tested against each other and against a control, with about 9,000 people in each of the three arms of the study.
In Sierra Leone, vaccine doses will be given to health care workers and others directly involved in responding to the disease. There will be no placebo, and effectiveness will be determined by looking at whether there are fewer cases of Ebola among workers who are vaccinated earlier compared with those who are vaccinated later. Which vaccine is used will depend on which one appears to be the best after data on immune responses is analyzed, Dr. Kieny said.
Guinea will test using the ring vaccination strategy, vaccinating communities when a case of Ebola occurs. Some communities will be given vaccine right away, and others will receive it later, based on random assignment."
Dr. Marie-Paule Kieny, an assistant director general of the W.H.O., said two vaccines had been found safe enough in early testing in countries outside the outbreak zone to justify wider testing in the affected countries. But she said it would take two to four weeks more to determine the proper doses.
She said a clinical trial in Liberia could begin as soon as the end of this month, with studies in Sierra Leone and Guinea starting in February.
Dr. Kieny said it could take up to six months to determine if the vaccines are effective. Production has already begun, so if any of the vaccines proves safe and effective, millions of doses could be quickly made available.
Vaccine effectiveness is determined by how many vaccinated people come down with a disease compared with those who are not vaccinated, or vaccinated later. If few new cases of the disease are occurring, it would be harder to see any difference. Dr. Kieny said plans were being made to increase the size of the trial in Liberia if needed.
In Liberia, there were eight confirmed new cases and 40 probable new cases recorded in the five days ending Jan. 2, down from a peak of 300 confirmed new cases a week in August and September, according to the W.H.O. The number of new cases has been falling in Sierra Leone, but it remains the most heavily affected country. In Guinea, it is not clear if case numbers are falling, the health organization said.
If the epidemic continues to ebb, it may be too late for the vaccines to make a difference in this outbreak. Dr. Rees said that a working group had been formed to discuss how to deploy the vaccines, should they prove safe and effective, but that the situation was changing too rapidly to make such a decision now.
“Hopefully, we will have broken the back of this epidemic by the time we finish these trials,” she said.
Even if that is the case, she and Dr. Kieny said, sporadic cases would most likely occur, and vaccinations might be given to people nearby to protect them and help prevent further spread of the disease — a strategy known as ring vaccination. And it might be wise to vaccinate health workers for long-term protection, they said.
The two vaccines that are most advanced in testing are being developed by GlaxoSmithKline and Merck. The Glaxo vaccine is being developed with theNational Institutes of Health; Merck’s was originally developed by the Public Health Agency of Canada and licensed to a small Iowa company, NewLinkGenetics, which in turn enlisted Merck.
Testing of the Merck vaccine at a hospital in Switzerland was suspended in December after a number of patients developed pain in the joints of their fingers and toes. Testing resumed this week using a lower dose. Dr. Kieny said the pain was generally transient and mild and “not of sufficient concern to stop the development of this vaccine.”
A third vaccine, being developed by Johnson & Johnson, began early safety testing in volunteers this month. That company is also planning tests in West Africa.
There has been debate over how to conduct the studies. Some experts say testing the vaccines against a placebo would be the surest way to determine whether they work. Others counter that it would be unethical to administer a placebo during a deadly epidemic.
The trials will cover all the approaches, with different designs in each country. In Liberia, the Merck and Glaxo vaccines will be tested against each other and against a control, with about 9,000 people in each of the three arms of the study.
In Sierra Leone, vaccine doses will be given to health care workers and others directly involved in responding to the disease. There will be no placebo, and effectiveness will be determined by looking at whether there are fewer cases of Ebola among workers who are vaccinated earlier compared with those who are vaccinated later. Which vaccine is used will depend on which one appears to be the best after data on immune responses is analyzed, Dr. Kieny said.
Guinea will test using the ring vaccination strategy, vaccinating communities when a case of Ebola occurs. Some communities will be given vaccine right away, and others will receive it later, based on random assignment."
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