For the general public, changing a new mask after each use is unnecessary, Feng Zijian, deputy director general of the Chinese Center for Disease Control and Prevention (CCDC), said at a press conference on Wednesday.

The guideline released by the National Health Commission regarding the prevention of the novel coronavirus recently suggests the public wear medical surgical or N95 masks when going out to public places or taking public transportation.

"This disease (novel coronavirus pneumonia) is transmitted through close human-to-human contact via droplets," said Feng, adding that when people are by themselves, for example, driving private vehicles or taking a walk at a park alone, wearing masks is not necessary.

For those who show respiratory symptoms, Feng suggested that they should wear masks during home observation and when going out to public places.

The CCDC official introduced during the press conference that the severe cases were mainly among middle-aged and elderly, and those with chronic underlying diseases have a higher risk of serious illness or even death.

"We have confirmed cases in children and infants, these cases are relatively mild," he said.

Feng said that proper crowd control measures are necessary within communities, and called on the public to actively participate in prevention and control of the outbreak.