The measles epidemic is something that "everyone should be concerned about," the president said today Joseph Biden.

He added that US health officials are considering potential therapies and vaccines.

"We are very engaged and trying to find ways to act," Biden told reporters in South Korea before leaving for Japan, the next stop on his Asian tour.

Meanwhile, the World Health Organization says it is working on additional guidelines regarding the outbreak of the disease.

"The WHO is working on additional guidelines to mitigate the spread of smallpox, due to concerns that the number of cases may increase further during the summer months," said David Hayman, chairman of the WHO Strategic and Technical Advisory Group on Infectious Diseases with Pandemic and epidemic potential.