Experimental Zika Vaccine Clinical Testing Begins
The United States government has begun the first clinical testing of an experimental vaccine designed to guard against Zika virus.
The National Institute of Allergy and Infectious Diseases made the announcement earlier this week.
The experimental vaccine has already been tested in animals.
Anthony Fauci, the institute's director, said on Wednesday that investigators should know soon whether the vaccine is safe for use in human beings. He said the first human tests involve 40 human volunteers in the U.S.
"If we get a good immune response and there are no safety red flags by the end of December 2016, we should know if it's okay to move on to phase II." He said the second phase could begin early next year.
Those trials will be larger studies, involving more volunteers. They would be performed in countries where Zika has spread. There, researchers would look not only at the safety of the experimental vaccine, but its effectiveness in fighting infection.
Infected mosquitoes can pass the virus to people. It can also be passed through sexual contact.
Zika usually causes minor problems in healthy people. But there is a real danger if an infected insect bites a pregnant woman. The infection could spread to the fetus she is carrying.
If infected with the virus, women can give birth to babies with a severe condition known as microcephaly. The heads and brains of those babies are unusually small. Microcephaly can cause many mental and physical problems and even death.
At first, the vaccine's main target will be women of the age when many women give birth. Researchers would also be looking to prevent the disease in the general adult population.
The vaccine was developed with a relatively new technology. It was scientifically engineered to contain a small piece of DNA from the virus. DNA is short for deoxyribonucleic acid, which contains the biological commands for Zika. The piece is so small that it is not infectious. But it is big enough to produce a reaction from the body's natural defenses for fighting disease.
Fauci said the DNA method makes it easy to provide the vaccine quickly. "We cannot afford to delay the development of a safe and effective vaccine to prevent Zika virus infection," he added.
Zika infections have been reported in 50 countries and territories. Most cases are in Central and South America and the Caribbean. This week, U.S. officials announced that a number of people in the state of Florida have been infected. They said all the infections resulted from infected mosquitoes.
I'm Anne Ball.
1.experimental vaccine 实验性疫苗
Scientists say an experimental vaccine reduced the risk of infection in humans by 31% and was safe.
2.guard against 防止；提防
Every effort should be made to guard against them.
3.immune response 免疫反应
This effect may be related to direct cytotoxicity and immune response.
4.passed through 通过；传递
He had passed through many difficulties during the experiments.
1.This week, U.S. officials announced that a number of people in the state of Florida have been infected.
a number of 若干；一些
We had to face up to a number of seemingly contradictory concerns.
Monkeys are transmitters of a number of dangerous diseases.
2.They said all the infections resulted from infected mosquitoes.
result from 导致；由...造成
Anemia may result from esophagitis.
They are hoping for a positive result from the experiment.
周三，该研究所所长安东尼·福奇（Anthony Fauci）称，不久后研究人员便可知晓寨卡疫苗对人体是否安全 。他说，首次人体测试在美国征集了40名志愿者 。
福奇表示，“如果疫苗获得良好的免疫反应，且到今年年底未出现任何安全警示，我们就可以考虑展开二期临床试验了 。”二期临床试验可能将在明年年初进行 。
二期临床试验规模会更大，参与的志愿者数量也会增加 。临床试验将选择在寨卡肆虐的国家进行 。在那里，研究人员不仅要观察实验性疫苗的安全性，还有其抗感染的有效性 。
寨卡病毒通过蚊子进行传播 。此外，还可以通过性行为进行传播 。
寨卡对健康人群造成的影响甚微 。但被感染的蚊虫叮咬的孕妇就会十分危险 。因为，寨卡病毒可能会传染给腹中的胎儿 。
倘若感染寨卡病毒，孕妇将产下患有小头症的婴儿 。被感染的婴儿头部和大脑小于常人 。小头症还会引发多种心理和生理问题，甚至导致死亡 。
起先，该疫苗主要针对的是育龄女性 。研究人员希望，普通成人种群也能接种预防这类疾病 。
这种疫苗采用一种新型技术进行研发 。这种疫苗经过科学地设计，取一小片寨卡病毒的DNA纳入疫苗 。DNA是脱氧核糖核酸的简称，该疫苗包含了寨卡病毒的生物指令 。这片DNA十分微小，因此不具感染性 。但是足以引起人体对抗疾病的免疫反应 。
福奇表示，这种DNA方法可以快速引起免疫反应 。他补充说，“我们已经没有时间等待安全、有效、可预防寨卡病毒感染的疫苗开发出来 。”
据报道，先后有50个国家和地区出现寨卡感染的病例 。多数病例集中在中南美洲和加勒比海地区 。本周，美国官员宣布，佛罗里达州出现了寨卡感染病例 。他们表示，这些病例均为遭本地蚊子叮咬后感染引起 。