Influenza A H7N9 viruses are a subgroup of influenza viruses that normally circulate among birds. Recently in China there have been reports of human infections for the first time from these viruses. However, there is no evidence to date that H7N9 can be transmitted human-to-human, and there have been no reported cases in the United States. Any time a new influenza subtype is discovered in humans it is a public health concern. The Center for Disease Control (CDC) is monitoring the situation closely. For more information, and new developments, click here.