Those last vials of smallpox, tucked away by the U.S. and Russia and due for destruction, have won at least another three years in existence -- suggesting other countries concur with the U.S. about their value, one leading health official said.

Delegates at the annual meeting of the World Health Organization agreed on Tuesday to wait until 2014 to decide on a firm deadline for the final destruction of the lethal virus, Reuters reports.

The World Health Organization has called for the destruction of such stockpiles since the disease was declared eradicated in 1980. The U.S., meanwhile, has argued that researchers need time to develop safe vaccines and antivirals in case other sources of smallpox are discovered.

The latest decision indicates that other countries agree with the U.S. position, says Nils Daulaire, director of the Office of Global Health Affairs at the U.S. Department of Health and Human Services.