Government health officials announced yesterday that an experimental treatment effectively reduces the number of serious bacterial infections in children carrying the AIDS virus, improving their quality of life.

The treatment does not cure the disease, nor does it appear to prevent death from bacterial infection, they noted.

At a news conference yesterday, National Institutes of Health officials issued a clinical alert about the treatment. This is a controversial new way of highlighting research results considered so important that the information should be channeled immediately into the hands of physicians.

Normally, such research is released in a scientific journal, but that process can take months even after a study is completed.

Since March 1988, researchers at the National Institute of Child Health and Human Development, and at 28 medical research centers around the country, have been treating 372 children under age 13 with intravenous immunoglobulin (IVIG). The preparation contains many different types of infection-fighting antibodies collected from thousands of blood donors.

Antibodies are a normal part of the body's defenses against infection. The IVIG treatment gives the children a type of artificial immunity from bacteria that cause such illnesses as pneumonia, meningitis and deadly infections of the blood.

Normally, the AIDS virus slowly destroys a person's immune system, eventually leaving the patient vulnerable to any passing virus or bacterium. In the children who still had some natural immunity, the IVIG treatment prolonged the time they were free of bacterial infections by more than 2 1/2 times, from 221 days in the children not receiving the drug to 583 days for those who did.

For children who had little immunity remaining because of the AIDS infection, however, the IVIG treatment made no difference in how often a bacterial infection developed. There also was no difference in the number of deaths among those receiving IVIG and those who did not.

Still, the treatment was considered so effective that an independent review panel recommended stopping the study a year early and announcing the positive results.

In a prepared statement, Health and Human Services Secretary Louis W. Sullivan called it a "significant advance in the treatment of children with HIV infection."

Ann Willoughby, chief of the child institute's pediatric, adolescent and maternal AIDS branch and the study's director, said it is not clear what significance the results have for adults with the disease. There is no research to suggest that giving IVIG to adults with AIDS will prevent the secondary infections that often kill them.

The current study has been controversial because most of the AIDS-infected children were not also receiving AZT, the only drug approved for use against the AIDS virus. The National Institute of Allergy and Infectious Disease is comparing children on both AZT and IVIG to children receiving AZT alone, to see if the combination not only reduces the number of bacterial infections but also prolongs the child's life.