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Şifremi Unuttum

Ebola Aşısı Yüzde Yüz Etkili!


Ebola aşısı yüzde yüz etkili!


2 Ağustos 2015

Korkulu rüya Ebola'nın çaresi bulundu
Uzmanlar Gine’de yaşanan salgın sırasında test edilen yeni Ebola aşısının %100 etkili olduğunu tespit ettiklerini açıkladı.

VSV-EBOV isimli aşının Merck isimli ilaç şirketi liderliğinde geliştirildiği ve Dünya Sağlık Örgütü tarafından düzenlenen deneylerde Aşının etkinliğinin test edildiği belirtildi.

Gine’de 4000 kişi üzerinde denenen aşının başarısının geçen yıl Batı Afrika’da on binden fazla kişinin hayatını kaybetmesine yol açan bulaşıcı hastalığın tarihe karışmasını sağlayacağı belirtildi.

Uzmanlar aşının Dünya’nın dört bir yanından doktorlar, araştırmacılar ve ilaç şirketlerinin 12 aylık ortak çalışmalarının ürünü olduğunu söyledi. Aşı geliştirme çalışmalarına fon sağlayan ülkelerden Norveç’in Başbakanı Borge Brende konuyla ilgili yaptığı basın açıklamasında “Bu hastalığın toplumları nasıl etkilediğini gördüğüm için bugün gelen haberler beni çok mutlu etti” dedi.

Gine’de yapılan deneme sonucu aşının etkinliği ile ilgili elde edilen sonuçlar Lancet dergisinde yayınlandı.

Aşının Ebola virüsü ile daha az zararlı bir virüs kombine edilerek üretildiği ve bu sayede aşılanan kişinin bağışıklık sistemini Ebola’yla savaşacak şekilde eğittiği belirtildi.

 

 

Sarah Boseley

Health editor

Friday 31 July 2015 16.44 BST

Rapid development and testing of drug may bring current epidemic in west Africa to an end and control future outbreaks, experts say


The 100% success rate of a vaccination trial against Ebola in Guinea is very promising, says the World Heatlh Organisation

A vaccine against Ebola has been shown to be 100% successful in trials conducted during the outbreak in Guinea and is likely to bring the west African epidemic to an end, experts say.

The results of the trials involving 4,000 people are remarkable because of the unprecedented speed with which the development of the vaccine and the testing were carried out.

Scientists, doctors, donors and drug companies collaborated to race the vaccine through a process that usually takes more than a decade in just 12 months.

“Having seen the devastating effects of Ebola on communities and even whole countries with my own eyes, I am very encouraged by today’s news,” said Børge Brende, the foreign minister of Norway, which helped fund the trial.

“This new vaccine, if the results hold up, may be the silver bullet against Ebola, helping to bring the current outbreak to zero and to control future outbreaks of this kind. I would like to thank all partners who have contributed to achieve this sensational result, due to an extraordinary and rapid collaborative effort,” he said on Friday.

There have been a total of 27,748 cases of Ebola in Guinea, Liberia and Sierra Leone up to 26 July, with 11,279 reported deaths, although the outcome of many cases is unknown and the toll will be significantly higher. In the week ending 26 July, there were just four new cases in Guinea and three in Sierra Leone.

Because of the diminishing number of Ebola cases in west Africa and the shifting nature of the epidemic, with many sudden small outbreaks occurring across the region, researchers hit on a novel design for the trial.

The “gold standard” approach would be to take a population at risk of Ebola and vaccinate half of them while giving the other half a placebo. Instead, the researchers used a “ring” design, similar to that which helped prove the smallpox vaccine worked in the 1970s.

When Ebola flared up in a village, researchers vaccinated all the contacts of the sick person who were willing – the family, friends and neighbours – and their immediate contacts. Children, adolescents and pregnant women were excluded because of an absence of safety data for them. In practice about 50% of people in these clusters were vaccinated.


Ebola virus: how it spreads and what it does to you

To test how well the vaccine protected people, the cluster outbreaks were randomly assigned either to receive the vaccine immediately or three weeks after Ebola was confirmed. Among the 2,014 people vaccinated immediately, there were no cases of Ebola from 10 days after vaccination – allowing time for immunity to develop – according to the results published online in the Lancet medical journal (pdf). In the clusters with delayed vaccination, there were 16 cases out of 2,380.

In another precedent-breaker, the trial was sponsored by the World Health Organisation because “nobody wanted to step into this role so we took the risk”, said assistant director-general, Dr Marie-Paule Kieny.

Funding came from the Wellcome Trust and other partners, including the governments of Norway and Canada. Others involved included Médecins sans Frontières, whose volunteer doctors were on the front line, and the London School of Hygiene and Tropical Medicine. About 90% of the trial staff were from Guinea, a country where no clinical research had been carried out before. The vaccine is made by Merck.

Kieny said: “We believe that the world is on the verge of an efficacious Ebola vaccine.”

The trial will continue, but without randomisation, which means that in Guinea, where there have been 3,786 cases and 2,520 confirmed deaths, every contact of a person who develops Ebola – and their contacts – will be offered it. Work in Gabon has now established that the vaccine is safe for children and adolescents, so they will be offered it, too.

In terms of vaccines, which are usually trialled in hundreds of thousands of people, Kierny said the numbers were small but highly promising. It is likely when larger numbers are collected that efficacy will be between 75% and 100%.

The future of two other potential Ebola vaccines, one from GlaxoSmithKline and the other from Johnson & Johnson, is now in question, because there are too few cases of Ebola for their trials to be completed.

The authors of the research said the ring design made it “logistically feasible” to conduct trials even in poor countries in the middle of a fading epidemic and it was a promising strategy for the future.

“This trial dared to use a highly innovative and pragmatic design, which allowed the team in Guinea to assess this vaccine in the middle of an epidemic,” said Jeremy Farrar, director of the Wellcome Trust and one of the world’s leading experts on infectious disease. “It is a remarkable result which shows the power of equitable international partnerships and flexibility.

“Our hope is that this vaccine will now help bring this epidemic to an end and be available for the inevitable future Ebola epidemics. This partnership also shows that such critical work is possible in the midst of a terrible epidemic. It should change how the world responds to such emerging infectious disease threats.”

John-Arne Røttingen, the head of infectious disease control at the Norwegian Institute of Public Health and chair of the trial’s steering group, said it had been a race against time in the most challenging circumstances.

“We are really pleased with the interim results,” he said. “It is really important to add the vaccine to the traditional hygiene measures we have used in the response so far. I believe this will be an important contribution to getting down to zero cases.”

Médecins sans Frontières said it was keen for the vaccine to be used in Sierra Leone and Liberia, where there were still cases.

Bertrand Draguez, MSF’s medical director, said: “In parallel with the ring vaccination we are also conducting a trial of the same vaccine on front-line workers. These people have worked tirelessly and put their lives at risk every day to take care of sick people. If the vaccine is effective, then we are already protecting them from the virus.

“With such high efficacy, all affected countries should immediately start and multiply ring vaccinations to break chains of transmission and vaccinate all front-line workers to protect them.”

Margaret Chan, the director general of of the WHO, said the vaccine trial’s success was a promising development. “The credit goes to the Guinean government, the people living in the communities and our partners in this project.”

The British government contributed £1m of the trial funding and has said it will increase that amount to help allow the testing to continue.

“Ebola has claimed thousands of lives and devastated communities across west Africa,” the international development secretary, Justine Greening, said. “The results of these UK-backed vaccine trials are hugely promising and represent a significant breakthrough in our battle against this deadly disease. The vaccine offers hope for a future where we never have to face an Ebola epidemic like this again.”

Trial data will now go to regulatory agencies in the hope of getting a licence for the vaccine that will allow it to be stockpiled for future Ebola epidemics. It is likely to be used only for people at risk in outbreaks and not given to whole populations.

The rVSV-ZEBOV vaccine is sometimes known as the Canadian vaccine as it was originally developed by the Public Health Agency of Canada before being sold to Merck to conclude the testing.

 

Successful Ebola vaccine provides 100% protection in trial


Ewen Callaway

31 July 2015

Study also demonstrates ability to develop a vaccine quickly during an outbreak.

Cellou Binani/AFP/Getty Images

A man gets vaccinated on 10 March 2015 at a health centre in Conakry, Guinea.

An experimental Ebola vaccine seems to confer total protection against infection in people who are at high risk of contracting the virus, according to the preliminary results of a trial in Guinea that were announced today and published in The Lancet. They are the first evidence that a vaccine protects humans from Ebola infection.

“We believe the world is on the verge of an efficacious Ebola vaccine,” Marie-Paule Kieny, the World Health Organization‘s assistant director-general for health systems and innovation, said during a press conference in Geneva, Switzerland, today.

The results also have implications for outbreak response in general. “This is illustrating that it is feasible to develop vaccines much faster than we’ve been doing,” says Adrian Hill, a vaccine scientist at the University of Oxford, UK, who is involved in testing a different Ebola vaccine. “We just need to go on and develop them and get on with them before outbreaks appear.”

An estimated 11,280 people have died during the current West African Ebola epidemic, according to WHO data as of 30 July.

Ring strategy

The Guinea trial — called ‘Ebola, ça suffit‘ in French (‘Ebola, that’s enough’) — tested a ring vaccination design, a strategy that was borrowed from successful smallpox eradication efforts in the 1970s. After one patient contracts the disease, their close contacts are vaccinated in the hope of stemming the onward spread of the virus.

The Guinea trial included two arms: one in which adults who had been in contact with someone infected with Ebola and their subsequent contacts were vaccinated shortly after the original patient developed Ebola, and a second in which contacts instead received the vaccine three weeks later2. The trial tested a vaccine called rVSV-ZEBOV, which is composed of an attenuated livestock virus engineered to produce an Ebola protein. The vaccine was developed by the Public Health Agency of Canada and then licensed to the drug companies NewLink Genetics and Merck.

Of the 2,014 people who received the vaccine immediately as part of the first arm, none developed Ebola ten days after getting the vaccine. The 10-day window allows the vaccine to summon an immune response and accounts for any pre-existing Ebola infection. (A few people in the immediate vaccination group, however, did develop the disease between 1 and 10 days after vaccination.) That compares with 16 infections among the 2,380 people in the second arm.

The findings mean that the vaccine provided 100% protection from the virus, though the study’s small size means that the vaccine’s true protection rate may be slightly lower, Kieny says. The authors of the paper put its true effectiveness at between 75% and 100%.

Hill describes the results as “excellent”. “This vaccine works very well for three weeks. That’s good news for an outbreak situation,” he says. However, it remains to be seen how long the protection against Ebola lasts. “Will it work at six months? This trial doesn’t tell us that. That’s the next stage,” he says.

Immediate vaccination

The results come from data up to 20 July, but Kieny said that no new infections have since been detected in people who got the vaccine immediately. On the basis of these results, she said the delayed vaccination arm would be ended, and all contacts would receive the vaccine immediately. Adolescents and children are now also likely to receive it.

Guinea’s outbreak is waning — just 4 cases were detected in Guinea during the week of 26 July — but Kieny said that the rVSV-ZEBOV vaccine should help to bring the outbreak to an end. “We will continue as long as there are cases,” she said.

Health officials began vaccinating patients in Guinea in April 2015, when dozens of patients there were still being diagnosed each week. At that time, Ebola was all but gone from Liberia and cases were down drastically in Sierra Leone, the two West African nations where different Ebola vaccine trials were being planned.

With case numbers waning, many experts saw the Guinea trial as the best hope of determining whether an effective Ebola vaccine was even a possibility. The ring vaccination design it used was more likely to return a statistically meaningful result, compared with other trial designs now being conducted in Liberia and Sierra Leone, because the patients enrolled in the Guinea trial were at a high risk of infection.

“A vaccine that didn’t exist in the clinic a year ago has shown not only to be effective in a phase III trial but to control an outbreak, which is a fantastic result,” says Hill. (Phase III is the stage of a clinical trial which determines whether a vaccine works and is generally required for regulatory approval.)

“This trial dared to use a highly innovative and pragmatic design, which allowed the team in Guinea to assess this vaccine in the middle of an epidemic,” said Jeremy Farrar, director of the Wellcome Trust in London, which helped to fund the trial, in a statement. “Our hope is that this vaccine will now help bring this epidemic to an end and be available for the inevitable future Ebola epidemics,” he said.

Stockpile excitement

In the wake of the trial results, the WHO has decided that the rVSV-ZEBOV vaccine will continue to be used in the current outbreak in Guinea as part of the clinical trial, Kieny said in the press conference. She also said that the WHO is now considering whether to approve the vaccine for general use. That could set the stage for establishing stockpiles to quell future outbreaks — which have tended to flare up in remote communities — and perhaps even for use in this epidemic, should the case numbers in Sierra Leone or Liberia flare up again.

“From a public health point of view, this is a really, really exciting finding,” says Seth Berkley, chief executive of Gavi, the vaccine alliance in Geneva, Switzerland, which funds vaccine access in low-income countries. His organization previously announced that it would pay for production and roll-out of an Ebola vaccine during the current outbreak, should one become available.

He notes that rVSV-ZEBOV is a ‘first-generation’ vaccine that is not ideal for stockpiling: it must be stored at –80° C and it protects against a limited number of species of the Ebola virus. He says that Gavi will work with researchers and industry to support the development of second-generation Ebola vaccines that target other Ebola virus species, as well as the closely related Marburg virus, and which do not require storage in expensive, laboratory-grade freezers.

In the meantime, however, he says, Gavi will consider buying one of the current first-generation vaccines.

Nature | doi:10.1038/nature.2015.18107

Updates & Corrections

Updated: This story has been modified since it was first posted to include further information from the press conference and a quote from Seth Berkeley.
Corrected: An earlier version of this story said that the results came from data up to 3 July; they in fact come from data up to 20 July.
Updated: The story has been modified since it was first posted with further information about the trial.
Updated: The story has been modified since it was first posted with quotes from Jeremy Farrar.

 

References

  1. Henao-Restrepo, A. M. et al. Lancet http://dx.doi.org/10.1016/S0140-6736(15)61117-5 (2015).
  2. Camacho, A. et al. Br. Med. J. 351, h3470 (2015).