AIDS IS plainly a special problem in hospitals. The disease is transmitted through blood and other body fluids with which hospital workers routinely come in contact. Three workers are now known to have been infected through such contact. No hospital wants to shrink from the sick, but every hospital wants to protect its staff. What to do?

One answer that quickly occurs is to test every entering patient, the better to know where the risk lies. There are problems with this. Not every infected person will yet test positive, and an assortment of difficult issues arises when a person does. Public health authorities also fear that a checkpoint at the hospital door might deter people from seeking needed treatment and drive that part of the population at risk underground. Thus the Centers for Disease Control have said that the best approach is to act as if every entering patient has AIDS and to adopt "universal blood and body-fluid precautions."

But hospitals will test -- many already are -- so now the CDC has also issued guidelines as to how this can properly be done. The rules are both sensible and humane. The CDC says the decision should be left to individual hospitals if not individual doctors. It says tests should be given only with the consent of the patient; patients should be told of the results, and those found to be infected should be carefully counseled. It calls for "confidentiality safeguards . . . to limit knowledge of test results to those directly involved in the care of infected patients or as required by law." And above all it lays on hospitals that set up a testing program the burden of "assuring that identification of infected patients will not result in denial of needed care or provision of suboptimal care." A two-tier system of care in which to some extent AIDS patients might be written off is in some ways the most horrible prospect of all.

AIDS, more than any disease in recent memory, confronts the society not just with medical but with philosophical questions. The hardest of these have to do with the balancing of the rights and needs of the sick against the rights and needs of the society at large. Because there is no cure and because of the ways it is mostly transmitted, AIDS has provoked an unusual share of panicky and demagogic responses. The CDC has calmly resisted both. It is walking a difficult line, and so far is doing it wel