The race to develop Ebola vaccines will soon be entering a new phase that can provide answers to the most important question: Is they actually work? In as little as 4 weeks, testing could begin in West Africa in people at risk of contracting Ebola virus with one of two vaccines that moved forward at an unprecedented pace, said, Marie-Paule Kieny, Assistant Director-General of the World Health Organization (WHO), at a press conference today in Geneva, Switzerland But.
a new question complicates studies. The number of new cases of Ebola fell unexpectedly fast in recent months, particularly in Liberia. That's good news, but it will be difficult to show that a vaccine works, because studies require a minimum number of new infections to prove that offers protection against the disease.
So far, called Phase I trials have given experimental vaccines Ebola in healthy volunteers are not likely to Ebola, the evaluation of the safety and immune responses. Last year, a panel of WHO decided that given the huge threat, it would be ethical to jump directly from these small studies in Phase III trials, which test efficiency. Phase II studies, which evaluate the safety and immune responses in more people-begin simultaneously.
At a WHO meeting held yesterday on the Ebola virus vaccines, an international group of experts discussed the latest developments, which described in the Kieny press conference:
-
vaccine manufactured by GlaxoSmithKline (GSK) -which contains a chimpanzee adenovirus laced with a gene that codes for the protein Ebola surface has registered all the volunteers in his essay phase I; the company is currently analyzing data to determine the best dose for the Phase III and whether to give it one or two times. This analysis should not take more than 4 weeks and Phase III trials could begin soon after. The company could have "a few million doses" of vaccine produced in mid-2015, Kieny added, although this number will depend on the required dose.
-
An initially made by NewLink vaccine gene but now manufactured by Merck must still register more volunteers in the study phase I. This vaccine uses a virus called livestock VSV, rather than the chimpanzee virus as a vector for transporting the Ebola gene. a study was halted after several participants developed arthritislike symptoms, but he returned later. the company can produce tens of millions of doses in 2015, Kieny said.
Kieny also discussed test plans adopted for each of the three countries most affected by the Ebola virus. the methodology and ethics of vaccine studies have been debated at length, and in the end, the three countries will each use separate models
-
Liberia will be a randomized, controlled trials-the gold standard in drug and vaccine test with three arms, each comprising about 9,000 people. We will receive the GSK vaccine, the second Merck vaccine, and the third will form a control group that received neither. Although the original plan was to target the Ebola frontline workers such as doctors, nurses and paramedics, researchers are now looking to recruit among the Liberian population in general. (Very few health care workers have been infected with Ebola recently virus.)
-
Sierra Leone will be a so-called stepped-wedge design in which groups receive the vaccine more earlier than others, and efficiency is displayed if the first group had fewer infections than this one. (This design takes longer to produce statistically significant responses, but is considered more ethical by some because all participants may receive the vaccine.) Kieny said the study will enroll about 6,000 frontline workers and Ebola will probably test the vaccine that elicits the strongest immune responses in the study phase I.
-
Guinea will test the vaccine-ring a strategy used to help eradicate smallpox- in which a group of people around a patient, Ebola is vaccinated. This variation on the stepped design area will have two arms, each with a 0 "rings", with an average of 50 vaccinated by cycle, which means a total of 9,000 participants in the trial. In one arm, the vaccine is given at the beginning, so that the rings in the other arm receive the vaccine later. Furthermore, the front-line workers will receive the vaccine in a so-called observational study that has no control group.
Tuesday, a third company, Johnson & Johnson, announced the launch of its own vaccine trial against Ebola. the phase I trial, conducted by the University of Oxford in the UK, is testing two shots in what is called a prime-boost strategy. the first shot, developed by Crucell in the Netherlands, using a human adenovirus vector. the boost that participants will receive 1 or 2 months later, is produced by Bavarian Nordic in Denmark and uses a modified version of the vaccine against the old smallpox, MVA as a vector. The company began scouting for the Phase III trial sites in the affected countries, Kieny said.
A third candidate is welcome, she added. Based on results to date, the vaccine twofold Johnson & Johnson would take longer to trigger robust immunity, but the protection may last longer; which could make it appropriate to vaccinate people potentially exposed to Ebola in the future, such as health care workers. Interim fastest vaccines could be useful in quenching homes, where the long-term protection is not as important.
While two other vaccines should be frozen, Johnson & Johnson products keep at temperatures between 2 ° C and 8 ° C, she said, a major advantage in remote areas. Tens of millions of doses of the two components of the vaccine can be produced in 2015, Kieny said.
First results for Phase III studies can be expected after 6 months or more. independent data and safety monitoring boards keep an eye on the tests and consider blind data as they come in; apart from side effects, a board can stop a study early if large areas of success or it becomes clear that the trial did not provide the statistical power of a clear answer.
But the dramatic drop in Liberia, of reason to celebrate, could throw a spanner in the works because it is more difficult to demonstrate that a vaccine to protect people when fewer people are at risk. If other virus control efforts are making significant progress, it could further undermine the power of the study. Kieny acknowledged that the risk and said that Liberia, where new cases have slowed to a trickle-decided to recruit more participants to increase the chances that the trial ends with a firm conclusion.
* The Ebola virus files: Given the current Ebola outbreak unprecedented in terms of the number of people killed and the rapid geographic spread, science and science Translational Medicine made a collection of research articles and news on the virus disease available for researchers and the general public.
0 Komentar