WASHINGTON, March 27: Top US health officials have suspended smallpox vaccination for people with heart problems, according to reports Wednesday.

The move follows reports from around the United States of severe heart problems in seven newly vaccinated medical staff, including one who died and one who is on life support.

The US Centres for Disease Control and Prevention (CDC), based in Atlanta, Georgia, has been administering a smallpox vaccination programme for health care workers in preparation for a potential terrorist-related outbreak of the eradicated viral disease.

The agency late Tuesday issued a temporary medical deferral for people diagnosed with heart disease, calling it a “precautionary step” while it investigates “whether there is any association between smallpox vaccination and reports of heart problems”.

Amid the buildup to the ongoing war in Iraq, coalition troops, media and other people heading to the region were also vaccinated over fears that the regime in Baghdad might have biological weapons that include smallpox.

“We promised to closely monitor this programme and to put safety first, so we are exercising exceptional caution,” said CDC director Julie Gerberding. “If our investigation shows this precautionary measure should become permanent or the need for other changes or enhancements in the civilian smallpox vaccination programme, we will take immediate action.”

The agency said that it detected the possible problem through its real-time monitoring system for smallpox vaccinations, which showed “a small number” of heart-related incidents after exposure to cowpox, a closely related virus that conveys immune system resistance to smallpox with usually only mild symptoms.

It was not clear whether the rate of heart problems was greater than would have been expected from the population of 25,645 vaccinated civilians, CDC scientists said.

The programme was controversial because smallpox vaccination in rare cases can cause serious side effects and even death.

“We continue to believe that it is important and necessary to vaccinate health care workers to prepare our nation in the event we have to respond to a smallpox outbreak,” Gerberding said.

Reports of heart inflammation after smallpox vaccinations were recorded in the 1960s and ‘70s, before routine smallpox vaccinations were suspended because the virus had been eradicated in the wild.—dpa