ANY LINGERING doubts about the severity of the AIDS tragedy were dispelled last week when Dr. Ruth Berkelman of the government's Centers for Disease Control announced that "the epidemic is here . . . and there's no let up in sight." As of the end of December, more than 100,000 Americans had died of AIDS. Federal health officials estimate that another million are infected by the HIV virus, and about 20 percent of them will die within the next two years. The disease continues to strike in the prime of life. Ninety percent of AIDS victims are male, and 75 percent are between the ages of 25 and 44. The disease is now the second most frequent cause of death, after injuries, among men in this age group, and by the end of the year it will be among the top five killers of women 25 to 44.

The news is not all bad. Until the illness can be cured, there will always be calls for more federal research money, but last year the amount appropriated was substantial. The Public Health Service now spends more on AIDS research, prevention, education and treatment than it does for these programs directed at cancer, though in terms of research dollars alone, cancer is still slightly ahead. The AIDS figure is just under $1.7 billion this year. There have also been changes in Food and Drug Administration procedures so that drugs showing promise in combating AIDS have been made available more quickly.

On the legal front, too, there has been progress. The Americans With Disabilities Act, passed last year, will protect those who have AIDS or who are HIV-positive from discrimination in employment, public services and public accommodations. And new immigration legislation gave the secretary of Health and Human Services the authority to remove AIDS from the list of contagious diseases that bar foreign visitors and immigrants. Secretary Sullivan took that step this month.

One aspect of the AIDS crisis that persists and grows worse involves the care and treatment of patients. The problem is most acute in the 13 metropolitan areas, including Washington, that have 55 percent of all AIDS cases. It is desperate for the 5 percent of the nation's hospitals that care for half of all AIDS patients. Last year, Congress responded by authorizing emergency relief to the cities hardest hit by the epidemic and grants to states for treatment and early intervention programs. But while $875 million has been authorized for these purposes, so far only $221 million has been appropriated. Overburdened municipal hospitals can no longer do this work without substantial federal help. It must be provided and states must be given the wherewithal to try less expensive and more sensible substitutes for hospital care, including home health services and hospices.