A new report says vaccines are the cheapest way to control the spread of infectious diseases, but they are not reaching people in the developing world.

While the latest vaccines are available to children in the developed world, the situation is very different in poorer countries. According to a joint report by the World Health Organization, the World Bank and the U.N. Children's Fund, just 50 percent of children in sub-Saharan Africa are immunized in their first year of life against diseases like tuberculosis, measles, tetanus, and whooping cough.

The report says in some developing countries fewer than one in 20 children are vaccinated.

Dr. Paul Fife of UNICEF said many developing countries are not able to buy vaccines that are widely available, and even discounted, in the industrialized world. He said UNICEF, the single largest buyer of vaccines for children, is also finding difficulty locating the needed medicines.

"Today we are basically buying for some of these vaccines anything that we can get our hands on," he said.

Dr. Fife said that next year the demand for vaccines will likely outstrip supply.

The head of the World Health Organization's vaccine program, Dr. Daniel Tarantola, has said one way to address the vaccine shortage is for more production in the developing world. "There are tremendous efforts, ongoing, which I think are successful to stimulate vaccine production in developing countries that will gradually make at least the large countries, China, India, Brazil, Indonesia self-sufficient in the key vaccines to be produced. That would contribute to both bridging the gap in terms of global vaccine supply, but also lowering the cost, we hope," he said.

The report said that although the market for vaccines in developing countries is potentially huge, with more than 130 million children born there each year, drug companies target most of their vaccines to the countries of the developed world.