Cases of measles, mumps and whooping cough have risen steadily over the last several years while the percentage of young children receiving vaccines has dropped, according to a recent report by the Children's Defense Fund.

Public health officials have become worried that if the trend continues, childhood diseases that are now considered minor problems in the United States could return in force.

"Anytime you have a disease that can be prevented by a vaccine, the effort of the nation should be to eliminate it," said Surgeon General C. Everett Koop. "Compare the cost of the vaccine -- in pain as well as money -- to the cost of the disease. We need to reach the children we are missing."

Health experts say that diminished federal funds have been responsible for at least part of the problem. As funds have been cut during the past five years, it has become increasingly difficult for poorer children to gain access to vaccines, according to the report.

The surgeon general has set as a health objective for 1990 that at least 90 percent of the nation's children have vaccines before they are 2 years old. But general levels of immunization for preschool children worsened between 1980 and 1985, according to federal statistics.

Progress toward the surgeon general's vaccination goals slowed or fell off for most major childhood diseases in the past five years, the Children's Defense Fund report says. For polio, measles, rubella, mumps and DPT (diphtheria, pertussis and tetanus), the percentage of children under two who received full immunization declined between 1980 and 1985.

During those years, the last for which there are complete statistics, the proportion of one- to four-year-olds receiving no doses of polio vaccine rose by 40 percent for children of all races and 80 percent for nonwhite children, according to the report. In addition, cases of mumps rose in 1986 after a 15-year decline, and in 1985 there were 3,589 reported cases of whooping cough, or pertussis, the highest number since 1970.

"This is becoming a very serious problem," said Dr. Richard Narkewicz, president of the American Academy of Pediatrics. "The immunization program in this country is a bulwark for the future health of our children. It has been built over years and it is beginning to erode."

Narkewicz cited several reasons for the drop in the percentage of children seeking immunization. The liability risks have driven the costs of vaccines up and pushed many drug companies out of the business. Also, because vaccines pose an inherent -- but incredibly small -- risk to children under two, some parents decide to avoid them.

"Many American pediatricians have never even seen whooping cough," Narkewicz said. "Because the disease is so rare a certain complacency begins to settle in. But as long as the disease is still out there, it cannot be ignored."

Many health officials believe that parental fears about bad reactions to vaccines have been blown out of proportion. Nearly 11 million children are immunized in America each year and about 30 to 50 -- at most one out of 220,000 -- have reactions that cause permanent damage.

But health officials agree that benefits of vaccines far outweigh possible risks. The Children's Defense Fund report, which used figures compiled by the federal Centers for Disease Control, said the number of measles cases reported has risen dramatically since 1983 and that more than 80 percent could have been prevented through adequate immunization.

The development of successful vaccines for most major childhood diseases have been regarded as a hallmark of modern medicine. Vaccines routinely protect children against seven diseases: polio, measles, mumps, rubella, diphtheria, tetanus and pertussis.

Statistics suggest that the decline in vaccinations can at least partially be attributed to access problems rather than parental decisions to avoid the shots. Poor and minority children consistently had the biggest drop in vaccination rates.

Vaccines against DPT give some illustration of the small but growing problem. The percentage of children from 1 to 4 years old with no reported dosages rose only slightly from 0.7 to 0.8 percent between 1980 and 1985, according to the report.

Complete protection requires a series of shots. The number of children younger than 1 only partially immunized against DPT climbed by 10 percent, from 15.8 to 17.3, while the percentage of nonwhite infants not fully immunized climbed 68 percent from 21.0 to 35.2 percent.

"The data suggests clearly that we are not providing immunizations for all the children who want them," said Kay Johnson, the analyst who wrote the report. "Funding has failed to keep pace with the needs."

She said that the costs of vaccines deterred many low-income parents, and added that more money is needed to fund the Childhood Immunization Program.

Final appropriation for the program in fiscal 1988 has been set at $86 million, $8 million below the full authorization level. That figure is slightly higher than current levels, but the price per dose of vaccine for measles, mumps and rubella has risen sharply over the past decade from $2.42 in 1975 to $8.47 last year, according to the report.

"By 1986 it took three times as many federal immunization grant dollars to purchase the same number of vaccine doses that were purchased in 1981," the report says.

The number of children younger than 6 has also increased over the past several years, from 18.8 million in 1979 to 21.7 million in 1986, and the number of poor and uninsured children rose dramatically. Between 1982 and 1985 the number of uninsured children increased by more than 16 percent.

"It all boils down to dollars," Narkewicz said. "But this makes sense economically as well as medically. No physician wants to let a child get a preventable disease."

-------------------------------------------------------------

HOW MANY CHILDREN ARE IMMUNIZED?

PERCENTAGE OF CHILDREN AGE TWO AND YOUNGER

-------------------------------------------------------------

-------------------------------------------------------------

Year.........Polio.....Measles.....Rubella.....Mumps.....DPT*

--------------------------------------------------------------

1980.........80.7%....83.0%....83.2%....80.2%....87.0%

1981.........80.9.....81.5.....83.9.....79.1.....87.6

1982.........78.6.....84.3.....81.1.....79.0.....88.4

1983.........78.6.....83.9.....81.9.....78.1.....88.4

1984.........74.2.....81.7.....76.7.....78.4.....85.8

1985.........76.7.....81.7.....77.3.....78.9.....85.8

-------------------------------------------------------------

1990

Objective....90.0.....90.0.....90.0.....90.0.....90.0

-------------------------------------------------------------

*Diphtheria, pertussis and tetanus

NOTE: Full immunization for DPT and polio at this age is defined as three or more vaccinations.

SOURCE: Centers for Disease Control