THE GOVERNMENT has now made a settlement with June Roberts, the McLean woman who contracted Guillain-Barre syndrome in 1976 when swine flu vaccine was urged on the whole population to prevent a major epidemic. Instead, the program turned into a nightmare, inflicting paralysis on some of those it was supposed to help and presumably implanting widespread suspicion of future similar campaigns. As one result, much effort was put into studying what had gone wrong, so that there would be no recurrence of the unfortunate aspects of the swine flu program.

In fact, the incident involving Mrs. Roberts does seem to be an exception -- a tragic one -- to a very impressive history of success in federally sponsored immunization programs. Viral vaccines like swine flu are tricky to deal with, and flu viruses themselves change rather quickly, so that making sure that this year's shot is for this year's flu turns out to be no easy matter, even apart from the possibility of malevolent side effects. For diseases like flu, it is difficult to be sure that the benefits of immunization outweigh the risks.

But one can be more certain in the case of childhood immunization, where efforts have been notably successful. The massive immunizations against polio in earlier years were dramatic and effective, and the clear-cut success of that campaign is taken not only as an occasion for nostalgia but as a model of what such a campaign can be.

A particular problem, however, has appeared in recent years. Either through lethargy or lack of understanding, the rate of systematic immuniation of children has gotten alarmingly low. In 1977 only 45 percent of the nation's children were being immunized against mumps, and about 75 percent for diphtheria, pertussis and tetanus. About 20 million children had not received a full range of shots. The significance of this is that, unless about 90 percent of the population is immunized, the diseases now rarely seen will begin to reappear.

Since 1978 the Center for Disease Control has coordinated a highly effective campaign to remedy this shortfall. By the end of 1979, the center's work with states and schools had raised the percentage of schoolchildren fully immunized above 90 percent. Moreover, reported cases of measles, rubella, tetanus, diphtheria and mumps were at an all-time low. It is a happy result, and it leaves the challenge now to keep up the good work.