U.N. to Commit Funds for ‘Children’s Vaccine’ Search : Health: World organization seeks a single-dose immunization against all major infectious diseases.

WASHINGTON —  The United Nations is expected to announce today that it will commit $150 million to begin development of a universal “children’s vaccine” that would provide protection against all major childhood infectious diseases with a single dose.

“We have taken a giant step toward harnessing the biotechnology revolution for the child survival revolution,” said James P. Grant, executive director of the United Nations Children’s Fund (UNICEF), one of three U.N. agencies sponsoring the project. The others are the World Health Organization (WHO) and the United Nations Development Programme.

“We can now begin to redirect our . . . objectives to protecting children against killer diseases with vaccines designed to meet the rigorous delivery requirements of the developing world,” Grant said in a statement.

Officials from the three agencies, which were scheduled to announce the program in New York today, predicted that the combined vaccine could save the lives of at least 8 million children in the developing world who die annually from these diseases, as well as prevent some 900 million episodes of severe illness.

International health experts have long believed that vaccine immunization programs represent the most cost-effective way to protect the world’s children from the major killers, which include polio, measles, tuberculosis, whooping cough, tetanus and diphtheria. But the programs are constrained by the need to administer multiple injections and follow-up booster shots, causing costs to increase and participation to fall off.

Despite the limitations, vaccination programs already have achieved a remarkable degree of success. In 1974, for example, only 5% of children in the developing world received vaccines for the major diseases, said Dr. Barry Bloom, a professor of microbiology at Albert Einstein College of Medicine in the Bronx. By 1990, however, the figure had jumped to 60% to 70%, “which is an extraordinary achievement,” he said.

“The vaccines have made an enormous impact,” said Bloom, who also serves as a consultant to the U.N. agencies. “Two million lives are saved each year that would have been lost in 1974. But we know we’re going to have great trouble--even with existing vaccines--getting from where we are now to all kids. That’s why we need new kinds of vaccines.”

A “dream” children’s vaccine would be designed to overcome the two biggest obstacles to successful immunization: It would require no refrigeration and would minimize a child’s contacts with the health delivery system, Bloom said.

“It would be a single-dose vaccine that contains all the substances required to protect children against the major infectious diseases, that is given once orally and that would remain stable without refrigeration,” Bloom said.

Most vaccines require refrigeration, a problem in the hot climates of many developing nations, and also require booster shots. With existing vaccines, complete immunization against the six major diseases now requires between seven and 14 contacts between a child and health providers, Bloom said.

For example, DPT, the combination vaccine that protects against diphtheria, pertussis (whooping cough) and tetanus, requires an initial shot followed at separate intervals by two boosters.

“For each booster in the Third World, about 15% of the kids drop out,” Bloom said.

He noted that only 14% of the expense of vaccinating a child is the cost of the vaccine itself. “The rest is the cost of getting it out there,” he said.

U.N. officials characterized a universal children’s vaccine as “a distant but achievable goal,” and would not predict when one might be available. Bloom speculated that such a vaccine could be developed within a decade, particularly as a result of advances in genetic and molecular engineering.

Work is under way on vaccine technology that can deliver booster shots with only one injection. The technique is called microencapsulation and involves administering antigens--substances that produce antibodies and provide immunity--in a biodegradable, “time released” delivery system.

Such a one-shot, controlled-release vaccine is now being developed for neonatal tetanus, which afflicts children in developing countries at the time of birth and kills an estimated 750,000 newborns annually. Currently, immunization for tetanus requires three injections.

U.N. officials said that another priority will be to develop vaccines for diseases for which vaccines are now lacking.

Such diseases include rotavirus, which kills 800,000 children annually from acute diarrhea; respiratory syncytial virus, an infectious disease of the lower respiratory tract that accounts for 40% of all acute respiratory infections in children under the age of 1; meningococcal meningitis, which afflicts between 600,000 and 1 million children annually, with a mortality rate of 20%, and dengue, a viral disease spread by mosquitoes that infects 30 million to 60 million people every year.

“New and improved vaccines will help us to save millions of young lives by extending the effective reach of preventive medicine,” Grant said.