葛兰素史克开发埃博拉病毒疫苗即将进入临床阶段

随着非洲遭遇了极其严重的埃博拉疫情大爆发，世界各国和WHO都开始慎重对待埃博拉病毒特效药物开发这一问题。而制药巨头葛兰素史克公司则早在去年就已经开始未雨绸缪，"悄悄"研制埃博拉病毒疫苗。葛兰素史克公司最近宣布公司正在开发一种新型埃博拉病毒疫苗可能对今后防控埃博拉疫情起到重要贡献。这一疫苗是公司2013年以3亿2千5百万美元的价格收购Okairos公司时获得的。目前葛兰素史克公司正在和NIH合作进行这一疫苗的早期开发研究，并希望在今年使其进入临床一期研究。

然而，埃博拉病毒疫苗可不是那么容易研制的，目前摆在开发者面前的有几大难题。首先就是很难招募到患有这种疾病的患者，甚至很难取得患者身上的样本。因为尽管此次埃博拉疫情非常严重，但整体而言，埃博拉病毒的传播都是十分有限的；此外埃博拉患者一旦死亡，其遗体会被迅速活化以免病毒的进一步扩散。这些都给疫苗的测试带来困难。另一个问题就是，目前埃博拉病毒的起源仍不清楚，尽管大多数科学家认为蝙蝠是其源宿主，但是如果无法确定其源宿主，将很难划分适用人群。本月早些时候，NIH曾表示希望加速埃博拉病毒的临床研究，希望有项目可以在9月份就进入临床阶段。

截止到8月13日，非洲共有1975名埃博拉患者，其中1069人已经死亡，死亡率约为55%，远低于之前的平均死亡率90%。

详细英文报道：

As Africa continues to experience the most severe Ebola outbreak in the disease's short history, the World Health Organization has deemed it ethical to offer unregistered interventions as potential treatments or preventive therapies, including investigational vaccines.

The announcement comes on the heels of news that GlaxoSmithKline ($GSK) may be able to deliver one such vaccine by 2015.

GSK acquired the vaccine candidate in the $325 million buyout of Okairos in May 2013. Now, Glaxo says it is working with the U.S. National Institutes of Health's Vaccine Research Center (VRC) to advance the development of the early-stage vaccine, which Glaxo says it has already evaluated in preclinical studies. In collaboration with the VRC, the drugmaker is now in talks with regulators to advance the vaccine to a Phase I clinical trial later this year.

"It is difficult to accelerate this process because of the many important steps that a candidate vaccine must go through to ensure that it is safe and effective," the company says in a statement on its website.

There are other huge clinical hurdles to testing Ebola drugs, especially a vaccine. For one, the disease is relatively rare and when an outbreak does strike, it tends to kill people quickly and burn out fast. This presents logistical problems for clinical trials, because it takes time to design and set up a trial and then enroll patients.

With Ebola, under no circumstances would researchers infect people with the disease to test a vaccine's protection in a clinical trial. Therefore, any clinical trial data would be based solely on safety in healthy volunteers.

Then there's the question of who would receive a vaccine. Scientists don't yet know where the Ebola virus originates--though the likely reservoir is believed to be bats--and it's also unclear how widespread the Ebola reservoir is. With zoonotic diseases like Ebola, a reservoir refers to a nonhuman animal in which a virus lives while waiting for new hosts to infect. What's more, experts have said that it's difficult to know whether an Ebola vaccine would be effective until years after it's administered.

Earlier this month, NIH said it expects to launch a clinical trial for an Ebola vaccine as early as September. The agency has revealed few details about the trial, and it's not clear whether the Glaxo vaccine is the jab in question.

According to WHO's latest numbers, released Aug. 13, the number of Ebola cases has climbed to 1,975, killing 1,069 of those--a 54% mortality rate.