THE USE OF VACCINES to reduce disease -- especially in young children -- has been one of the most dramatic triumphs of modern medicine. In 1960, there were 14,809 cases of pertussis, or whooping cough. Childhood vaccinations reduced the number to 1,248 by 1981. But people have begun to take that success for granted and are getting careless about seeing to it that all children are protected by shots.

The U.S. surgeon general, for example, set a 1990 goal of no more than 1,000 cases of pertussis, but the trend is now moving in the opposite direction. The federal government slowed the increase of funds to pay for public health programs, despite sharp increases in the cost of vaccines. The Children's Defense Fund says that the number of young children receiving vaccines has dropped and that disease is on the rise.

Some 3,589 children contracted pertussis in 1985. Half of them had to be hospitalized. There were 9,000 cases of mumps in the first half of 1987, four times the number during the same period in 1986. Most of those who have not received vaccines are poor or minority children, the same groups that suffer the highest rates of infant mortality.

Some vaccines have severe, although rare, side effects. Parents sue the drug companies, and the cost of liability insurance has soared, driving many drug manufacturers out of the market. Those that remain have raised the price of vaccines high enough to cover liability risks and more. Federal funding has not kept pace. It now takes $3 to purchase the same amount of vaccine bought with $1 in 1981. The poor cannot afford them.

That means less vaccine protection of the kind that is really crucial. There is a rising risk of epidemics on a scale that this country has not seen for a generation. What should be done? The federal Childhood Immunization Program is set to receive $86 million in fiscal year 1988, $8 million below full authorization. More than that $8 million is needed. Bills pending in Congress would grant immediate Medicaid coverage for the poorest youths. More federal funding would allow the Centers for Disease Control to stockpile vaccines.

There are many ways to hold down federal spending. Limiting funds for vaccinations is perhaps the worst way to do it.