The Centers for Disease Control and Prevention says there is a reported spike in human metapneumovirus (HMPV) in China, and they are monitoring it closely.

The CDC’s actions come in response to China's government-run media confirming that positivity rates of HMPV hare rising in children under the age of 14, despite respiratory illnesses being down overall since last year.

As cases of the HMPV virus continue to increase in the U.S. and in China, here's what you need to know about the virus.