VACCINATION OF small children is an indispensable part of the public health system that protects them. But some vaccinations -- particularly for pertussis, or whooping cough -- carry a risk of a severe reaction. Statistically it is a very small risk, but in the care of children, no risk is negligible. Since the reaction, in extreme cases, can lead to brain damage or even death, the necessity for vaccination poses an urgent question to society: who bears responsibility for the rare but dire injury? Rep. Henry Waxman's health subcommittee is working on a compensation bill, and a hearing this week took up the full range of difficult choices here.

If there were an automatic compensation program outside the court system, should the families of injured children also have a right to go to court and sue? One parents' group, Dissatisfied Parents Together, argues that they should; these suits, it says, are the public's most effective weapon to force reform. These parents ask three pointed questions. First, is the present vaccine the most effective and safest that science can provide? Second, does the present spotty reporting of reactions give an accurate measure of the present risks? Third, should all children be vaccinated without exception -- including those whose own medical histories, or their families', indicate a possible allergy? Dissatisfied Parents Together believes that the answer to all three questions is no. It supports general vaccination for whooping cough, but concludes that the risks currently are higher than they need to be.

There the parents make a persuasive case. It is less clear that product liability suits are the right instrument to produce the necessary changes. Recently the suits seem to have been producing another and less welcome response. The price of whooping cough vaccine is now something like 20 times higher than it was two years ago, and the producers say that liability litigation is the principal reason. One major manufacturer dropped out of the business several months ago, and the American Academy of Pediatrics says that shortages have appeared in a dozen states. There are now only two producers of whooping cough vaccine in the country -- and only one producer of each of several other widely needed vaccines, including those for polio, measles and mumps. The Department of Health and Human Services is beginning to stockpile vaccines against the possibility that one or another of these manufacturers might discontinue production.

Mr. Waxman's hearing drew a portrait of a health protection program that is not working as well as a lot of people -- parents, doctors, drug manufacturers, public health administrators -- think it can be made to work. The legislation now taking shape will constitute an importnt redefinition of social responsibility. Vaccination is crucial to children's health, and effectiveness does not require sacrificing equity.