VOA慢速英語(yǔ):尋求可在常溫下保存的疫苗

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By VOA

05 May, 2014

Hello, and welcome back. I'm Jim Tedder in Washington. Today we will help you improve your American English while giving you some new information about medicines. This is the kind of thing that may save lives.

Then we turn to the world of American politics. The United States has never had a woman President. Could Hillary Clinton become the first one? Stay with us and hear what the experts are saying.

Looking for Vaccines Outside the Cold Chain

As It Is is coming your way from Washington.

Most vaccines must be kept in a cool place all during the time when they are being transported and used. That is a big problem in some developing countries where electricity and transportation are not always available.

Some non-governmental organizations are urging drug makers to investigate whether their vaccines can be shipped safely at room temperature. One such group, Doctors Without Borders, believes that room temperature vaccines – vaccines that are outside what has been called the "cold chain" – will reach more people. Anna Matteo has the story.

The "cold chain" requires that vaccines be kept in a cool environment, with no changes in temperature, until they reach the end user. This "cold chain" is supposed to keep the medicine effective and stop it from going bad.

But the group Doctors Without Borders says the cold chain leads to vaccine shortages. And it warns these shortages result in 20 percent of children below the age of one going without their vaccinations each year.

Kate Elder serves as a vaccine advisor to the group. She says that because most vaccines are produced by Western drug makers, keeping them cold is not a problem in developed countries. The problems start, she adds, when you try to provide these medicines in other countries.

"But when you get into context like Chad and Democratic Republic of the Congo and South Sudan, where electricity is scarce and where roads are very poor and transportation very difficult, it becomes a huge challenge to keep these relatively fragile commodities cold all the way through to areas where kids need them."

So Doctors Without Borders is urging drug makers to test vaccines to see whether they can be kept at temperatures up to 40 degrees Celsius.

One vaccine that stays effective at higher temperatures is MenAfriVac. It is used to prevent meningitis-A in children in African countries where meningitis is a big problem. MenAfriVac is effective without refrigeration equipment for up to four days.

Another such vaccine is the tetanus toxoid vaccine from the Serum Institute of India. A research group from France recently tested the tetanus toxoid vaccine in Chad. The researchers found that it too worked outside the "cold chain." It stayed effective for up to one month at temperatures up to 40 degrees. And it gave the same level of protection as the vaccine kept in a strict "cold chain."

Kate Elder says the results suggest that more immunization drugs probably do not need refrigeration all the time to be safe and effective.

"The number of these vaccines might actually be more thermo-stable than what they are labeled for at refrigeration requirements of two to eight degrees Celsius. So, what we are doing is pushing the manufacturers - the companies that make these products - to make sure that we can use them to that utmost thermo-stable potential."

Doctors Without Borders is urging drug makers to lead this effort – an effort that shows some vaccines may be safely transported and used when stored outside the "cold chain." This effort will lead to vaccines that can be approved for use in parts of the world that do not have dependable refrigeration – places that usually have the greatest need.

I'm Anna Matteo.