CDC begins preparations for H7N9 vaccine NHK The US Centers for Disease Control and Prevention says it is gathering more information and beginning preparations to develop a vaccine for the H7N9 strain of avian flu, which has killed 2 people in China. This is the first time the H7N9 virus was detected in humans. Chinese health authorities say 5 more people have been infected and all are in critical condition. In a comment issued on Tuesday, the CDC stressed the need to assess the infectivity of the new virus. It also said it has begun to take steps for developing a vaccine, such as reviewing the genetic sequencing of the virus. The CDC added that such actions are routine preparedness measures taken whenever a new flu virus is detected in humans. The CDC said the situation is still evolving, and it is too soon to speculate regarding the significance of the virus, but it will provide updated information as soon as it becomes available.