Health officials now know of 24 people who've fallen ill with a new strain of bird flu in China, seven of whom died, according to the World Health Organization. Of the three most recent cases, two occurred in Shanghai, and one in the eastern province of Jiangsu, WHO says.
The new strain, H7N9, is concerning because it has never before been seen in people, and so the general population presumably does not have immunity to it. So far, the virus does not appear to readily pass from person to person. WHO is monitoring 530 close contacts of those who fell ill and investigating the case of one contact who developed flu symptoms. No vaccine is available, but last week, the U.S. Centers for Disease Control and Prevention announced it had started work on a vaccine in case it's needed.