This is the VOA Special English Health Report.

In 1987, H.I.V./AIDS joined a list of diseases that could keep a person out of the United States. The government later tried to cancel its decision. But Congress made the travel ban a part of immigration law. People with H.I.V., the virus that causes AIDS, could seek an exception, but that meant extra work.

Last year, Congress and President George W. Bush began the process of ending the travel ban. Now President Obama is finishing that process.

BARACK OBAMA: "We talk about reducing the stigma of this disease, yet we have treated a visitor living with it as a threat. We lead the world when it comes to helping stem the AIDS pandemic, yet we are one of only a dozen countries that still bar people with H.I.V. from entering our own country."

A final rule published Monday will end the travel ban effective January 4th. H.I.V. will no longer be a condition that can exclude people. And H.I.V. testing will no longer be required for those who need a medical examination for immigration purposes.

AIDS has killed more than 25 million people since the early 1980s.

In September, there was news that a vaccine showed some ability to prevent H.I.V. infection in humans for the first time. The full results of the vaccine study were presented in late October at an international conference in Paris. They were also reported in the New England Journal of Medicine. The researchers confirmed that the study in Thailand produced only "modest" results.

The United States Army sponsored the vaccine trial. The study combined two vaccines, using versions of H.I.V. common in Thailand. Neither vaccine alone had shown success in earlier studies.

Thai researchers tested the combination in more than 16,000 volunteers. Half of the volunteers got the vaccine. The others got a placebo, an inactive substance. All were givencondoms and counseling on AIDS prevention for three years. The study found 31 percent fewer cases of infection in the vaccine group than in the placebo group.

But critics said the findings could possibly have resulted from chance. The announcement in September was based on all 16,000 volunteers. Almost one-third of them, however, did not follow all the required steps in the study. Results just from those who did were similar to the larger group, but the influence of chance was more of a possibility.

Still, the researchers said the study produced enough valuable information to offer new hope for AIDS research.

And that's the VOA Special English Health Report. I'm Bob Doughty.

placebo: something of no intrinsic remedial value that is used to appease or reassure another 安慰劑

condom: a sheathlike covering of thin rubber worn on the penis or in the vagina during sexual intercourse to prevent conception or infection 避孕套

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（Source: VOA 英語點津編輯）