Shenzhen has confirmed 207 novel coronavirus cases as of Sunday at noon, and epidemiological investigation for three of them is still underway. Experts suspect the three cases were community transmissions.

Among the three was a delivery man working until onset of the virus, who had no clear record of contact with infected persons; a woman who refused to cooperate with the epidemiological investigation, and another woman who had visited restaurants and a gym.

The three did have some things in common. None left Shenzhen over 14 days, the longest incubation period of the virus, before being diagnosed. They had not been to affected areas, nor had close contact with infected people or those suspected to be infected.

The Shenzhen Center for Disease Control and Prevention announced the three cases are scattered, and warned that during the transmission of infectious diseases it is common for community transmission to occur.

Experts also stressed the importance of wearing masks, avoiding crowded places and washing hands frequently and correctly.