骆驼是元凶

中东呼吸综合症冠状病毒（MERS-CoV）是一种新出现的人畜共患病，即可以从动物传染给人类的疾病。2012年首次在阿拉伯半岛（Arabian Peninsula）在人群中发现这种病毒，到2014年已传播到美国。人类一旦受到感染，可以通过密切接触将疾病传播给其他人。因为感染起源于动物，国家过敏症和传染病研究所的科学家们首先研究了该病毒在动物体内的形态。单峰骆驼被确定为主要的疾病源头。科学家们还发现骆驼具备MERS病毒的抗体，这可能是开发治疗方法和疫苗的关键[请见英文资料]。

基孔肯雅热

与MERS一样，基孔肯雅热（chikungunya）是一种正在传播的严重疾病，目前尚没有有效的疫苗。近年来，基孔肯雅热已经从非洲和亚洲蔓延到加勒比海以及西半球其他地区。所幸的是一种基孔肯雅热疫苗已经在研发中，福奇表示在第一阶段研究中，即确定疫苗对人类是否安全的小规模临床试验之后，疫苗“看起来是安全的”。规模更大的第二阶段试验将在2015年后期进行。福奇说：“它看起来真的很有潜力，但是只有在进行临床测试之后，才能真正确定它的效力。”

疟疾和结核病

能够防治全世界最根深蒂固、最有害的两种疾病——疟疾和结核病——的疫苗目前尚未研发成功。[请见防治疟疾行动计划力争根除这一导致儿童死亡的疾病以及国际防治结核病日力争治愈每一位结核病患者]

国家过敏症和传染病研究所与制药公司葛兰素史克（GlaxoSmithKline）合作研发了一种疟疾疫苗，但它所提供的保护不够广泛。不过，福奇说：“这是研发疟疾疫苗的重要的第一步。现在我们有了初步显示出一些效果的候选疫苗，2015年我们的疫苗研究工作进展会顺利很多。”

有些疫苗并不是对每个人、或者每一种病毒株都有效。例如，BCG疫苗可以保护儿童，但不能保护成年人，并且只对一些、而不是所有结核病毒株有效。福奇说：“结核病是一种非常特殊的疾病，因为发病机理和免疫系统在结核病中的作用在某种程度上仍是一个谜。”这也是他认为开发一种广泛适用的结核病疫苗“将相当具有挑战性”的原因之一。结核病每年导致大约150万人死亡，并且三分之一的世界人口患有潜伏性结核病。

我们的目标是将那些通过世界各地的免疫计划挽救了无数生命的疫苗的成功经验加以推广。[请见将免疫保健落实到所有人和所有地方]

New vaccines can take the bite out of diseases

Vaccines have helped control and even eradicate many deadly diseases, including polio and smallpox, which is why Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health (NIH), calls vaccines “one of the greatest tools in medicine.” Through the Vaccine Research Center, established in 2000, the NIH collaborates with universities, pharmaceutical companies and governments worldwide to pioneer and test new vaccines to combat a wide variety of communicable diseases.

Camels are the culprits

The Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging zoonotic — a disease that can be transmitted from animals to humans. It was first reported in humans in the Arabian Peninsula in 2012 and had spread to the United States by 2014. Once infected, humans can transmit the infection to others through close contact. Because the infection originated in animals, NIAID scientists first studied how the virus behaves in animals. The dromedary camel was identified as the chief disease reservoir. Scientists also found that thecamels had antibodies to the MERS virus, which could be a key to developing treatments and a vaccine.

Chikungunya

As with MERS, chikungunya is a serious disease that is on the move and for which there is no proven vaccine — yet. In recent years, chikungunya has spread from Africa and Asia to the Caribbean and other parts of the Western Hemisphere.  Fortunately, a chikungunya vaccine is in the works, which Fauci says “looks safe” after a Phase I study — a small-scale clinical trial to determine if a vaccine is safe for humans. A larger, Phase II trial will be conducted later in 2015. “It really looks quite promising,” Fauci says, “but you never really know until you test it in the field to see that it actually does protect.”

Malaria and TB

Vaccines to counter two of the world’s most persistent and pernicious diseases, malaria andtuberculosis (TB) , remain elusive.

NIAID collaborated with pharmaceutical company GlaxoSmithKline on a malaria vaccine, but the protection was not as broad as needed. Nevertheless, “it’s an important first step toward a malaria vaccine. So we are much better off in 2015 with the malaria vaccine now that we have one candidate that has shown some modest effect,” Fauci says.

Some vaccines don’t work for everyone — or against every strain of virus. For example, the BCG vaccine protects children, but not adults, against some — but not all — strains of TB. “TB is a very interesting disease because the pathogenesis and the role of the immune system in TB are still somewhat of a mystery,” Fauci says, one reason he thinks developing a broad TB vaccine “is going to be quite challenging.” TB causes about 1.5 million deaths per year, and one-third of the world’s population has latent TB.

The goal is to replicate the success of vaccines that, through immunization programs around the world, have saved countless lives.