A picture of millions of Americans bursting with health while others are dying for lack of medical attention was drawn yesterday by the Department of Health, Education and Welfare.

A similar picture -- of millions with adequate health insurance but others who have little or none -- was simultaneously drawn by the Congressional Budget Office.

The contrasts are contained in two new reports -- HEW's "Health, United States, 1978," and CBO's "Profile of Health Care Coverage: the Haves and Have-Nots."

"Americans are among the healthiest people in the world," said HEW Secretary Joseph A. Califano Jr. in addressing the first report to President Carter, but "serious health problems" remain. For example, he said:

"The nation's death rate in 1978, as in 1977, was 8.8 per 1,000 persons, a record low, yet one death in every eight might have been prevented "had there been the appropriate medical intervention."

Infant mortality in 1976 (all figures are the latest available) was just 15.2 per 1,000 live births, compared with 16.1 in 1975. But one-fourth of all women who had babies did not see a doctor during the first three months of pregnancy, when prenatal care should begin in order to give the babies the best chance.

Thirty-five of every 100 teen-agers were sexually active in 1976 -- compared with 27 in 1971 -- but only 30 of the 100 used contraceptives.

Thirty-six percent of persons over 40 have never had an electrocardiogram to check their hearts. Half of all Americans did not see a dentist in 1977, and 20 percent of adults and school-age children had not seen a dentist in at least five years.

On the plus side: life expectancy is slowly rising. In 1976 it was 69.7 years for a newborn white male, 64.1 for a nonwhite; 77.3 years for a white female, 72.6 for a nonwhite. A 65-year-old man, white or black, could expect to live nearly 14 years more, on the average; a woman, 65, about 18 years.

On the negative side: health care costs have been rising far faster than any payoffs in increased health or life.

Califano called for efforts to increase the health care establishment's "productivity."

The Congressional Budget Office offered no recommendations. But it said that in 1978 more than 90 percent of Americans either had private health insurance or were eligible for public programs that protect them from illness "to some degree," while 5 to 8 percent had no protection.

A larger but hard-to-calculate number, said CBO, had "inadequate" or "shallow" insurance that offers some coverage but not enough. For example, "at least 15 percent" of the supposedly insured lacked protection last year against high-cost health "catastrophes," and "roughly 9 percent of all families had out-of-pocket medical expenses" amounting to more than 15 percent of their income.