Secretary of Health and Human Services Richard S. Schweiker, who was accused earlier this year of underfunding child-immunization grants, has reversed position and asked the Office of Management and Budget to approve an additional $6 million in fiscal 1982 and $5.5 million in fiscal 1983.

Two of those who criticized the administration on the issue earlier this year--Rep. Henry Waxman (D-Calif.), chairman of the House subcommittee with jurisdiction over the grants, and Sen. Edward M. Kennedy (Mass.), senior Democrat on the Senate committee with jurisdiction--praised Schweiker's request for added funds when asked for comment yesterday.

"We cannot allow children to die of diseases that should never occur, and we cannot afford to treat children for crippling conditions that we can prevent," Waxman said. But he said that the program could use still another $5 million this year.

Kennedy said, "At long last the myth that the president's budget did not underfund childhood immunizations has been punctured . . . . It would be shameful" for the Office of Management and Budget "not to approve this request."

Schweiker, in a letter to budget director David A. Stockman, a copy of which was obtained by The Washington Post, said that when his department first proposed cuts in funds for immunization grants last year, it believed the requested amounts could fund all needs, despite the criticism from many on Capitol Hill and in the medical community.

However, price increases for vaccines, including a May increase for measles-mumps-rubella vaccine, had raised the cost of vaccines by 40 percent in fiscal 1982, Schweiker wrote, "and there is likelihood of further vaccine price increases later in the year."

He asked Stockman to boost the fiscal 1982 funding for immunization grants to the states from the $21.8 million appropriation to $27.8 million, with the extra money to come from other programs or dormant accounts. For fiscal 1983, the Reagan administration request of $21.9 million should be boosted to $27.4 million by an added appropriation, he said. The program had been funded at more than $24 million a year for the two years before President Reagan took office.