Up until Saturday, when Beijing officials reported the capital's first case of H7N9, all cases had been in Shanghai and other areas of eastern China. On Sunday, officials announced the first two cases in central Henan province, which is next to Beijing.
It's not the case that everyone confirmed to be infected with H7N9 was "clustered in one small area with the same source of exposure," said Michael O'Leary, head of WHO's office in China. "So we've been expecting new cases to occur. ... Furthermore, we still expect that there will be other cases."
A 7-year-old girl was Beijing's first confirmed case of H7N9. Four more cases were reported Sunday in eastern Zhejiang province and two more in Jiangsu, bringing to 57 the number of people sickened from the virus. Eleven of the victims have died.
Health officials believe the virus, which was first spotted in humans last month, is spreading through direct contact with infected fowl.
O'Leary said "the good news" was that there was still no evidence that humans had passed on the virus to other humans.
"As far as we know, all the cases are individually infected in a sporadic and not connected way," he said, adding that the source of infection was still being investigated.
The girl, whose parents are in the live poultry trade, was admitted to a hospital Thursday with symptoms of fever, sore throat, coughing and headache, the Beijing Health Bureau said.
O'Leary said early treatment can be effective, as demonstrated by the girl, who was in stable condition.
In the only other reported cases outside of eastern China, health officials in Henan province said tests on two men Thursday had later revealed they had the virus.
They said a 34-year-old restaurant chef who had displayed flu symptoms for about a week was in critical condition in a hospital, while a 65-year-old farmer who was in frequent contact with poultry was in stable condition after receiving treatment.
They said 19 people who had been in close contact with the two men did not show any flu symptoms.
China has been more open in its response to the new virus than it was a decade ago with an outbreak of SARS, when authorities were highly criticized for not releasing information.