More than 1,700 Chinese medical workers have been infected by the new virus that has killed nearly 1,400 people and spread to other parts of Asia and as far as the U.S. and Europe, a senior Chinese official announced today.

Six of the workers have died, Zeng Yixin, vice director of the National Health Commission, said at a news conference.

The health commission is “highly concerned about this issue” and has issued guidelines for the prevention and control of infection within medical institutions, he said.

Medical workers account for about 3.8% of confirmed cases as of several days ago, Zeng said.