As many as 2 million children under the age of 5 - about 8 percent of the population - are not getting shots for measles, tuberculosis and other illnesses, said Bernard Krisher, who runs the Internet Appeal for North Korean Children.
Krisher's assessment underscores the damage North Korea's economic collapse has wrought on the communist country's health system. He said shortages of fuel, electricity and money have slowed distribution of drugs and forced the closure of factories that produce vaccines.
"They just don't have the equipment and the material," Krisher told reporters in Beijing.
Krisher said he has visited hospitals in North Korea three times, most recently in 1997, and is in contact with UNICEF officials in Pyongyang, on whose behalf he raises donations.
He said UNICEF needs $2.8 million to immunize all affected children but only has about $450,000 of that amount.
The grim picture of children suffering in the secretive Stalinist regime coincides with similar accounts by other aid agencies.
The head of the U.N. World Food Program warned last week that food supplies probably will run out in North Korea by the end of this month, leaving many of the country's 23 million people to fend for themselves until the summer harvest begins in July.
Droughts, floods and tidal waves since 1995 have devastated North Korea's economy, which already was reeling from the collapse of the Soviet Union. The loss of barter trade with Moscow and other East Bloc partners cut off Pyongyang from such vital materials as fertilizer and tractor fuel.
Aid officials have warned that malnutrition is widespread among children, leaving the possibility of an entire generation whose growth has been stunted. Aid workers in North Korea report children aged 5 to 15 looking half their age.
Malnutrition has caused a drop in resistance against diseases. Krisher said UNICEF has found that children are more prone to lung and digestive infections.
"It's not starving like in Somalia. It's a slow starvation," said Krisher. "People are getting one-quarter to one-fifth of the rations of 5 or 6 years ago."
By Martin Fackler