Babies who have colds when they get their measles shots appear less likely to develop protection against the potentially deadly disease than infants who are healthy, researchers reported this week.

A study of 98 babies ages 15 to 18 months found about one-fifth of infants who had colds or mild upper respiratory infections at vaccination time did not develop a protective immune response against measles.The vaccine failed to work in 11 of the 47 babies with the sniffles, compared with just one - about 2 percent - of the 51 healthy babies.

Researchers measured vaccination success, called seroconversion, by looking at whether the children produced disease-fighting proteins, called antibodies, against the measles virus.

"We conclude that infants with colds have significant seroconversion failure rate associated with measles vaccine administration and that this may be the cause of some primary measles vaccine failures," Dr. Marvin Krober of Madigan Army Medical Center in Tacoma, Wash., and his colleagues wrote in the Journal of the American Medical Association.

The study did not look at the mechanism by which colds boosted the risk of vaccine failure.

Measles is caused by a virus. The disease, which usually affects children, is characterized by rash, fever and cold-like symptoms. Most patients get better after about a week, but some develop potentially deadly complications like pneumonia and brain infection.

About 500,000 cases of measles occurred annually in the United States until a vaccine was developed in 1963. Health officials once had hoped the vaccine would enable them to eradicate the disease from the United States by 1982.

But there has been a recent explosion of measles in the United States, with more than 26,000 cases reported in 1990, mostly among preschool children living in the inner city. Vaccine failure, along with unvaccinated preschool children, are thought to play significant roles in the troubling resurgence of measles.