In China, only patients showing symptoms and positive results in nucleic tests are included in the official tally of confirmed cases. Asymptomatic patients who have tested positive are monitored and placed under quarantine until they develop symptoms or turn negative in later tests.
The World Health Organization, however, says in its guideline that "a person with laboratory confirmation of COVID-19 infection, irrespective of clinical signs and symptoms" should be counted as a confirmed case.
The risk posed by asymptomatic cases has drawn significant attention in China in recent days. Addressing these concerns, Wu Zunyou, a spokesman for the Chinese Center for Disease Control and Prevention, said at a news conference Tuesday that the asymptomatic patients had all been found when monitoring those who had come into close contact with confirmed cases.
"Will they cause the spread (of the virus)? No they won't," Wu said.
"Why? Because in China, under our current measures, all close contact (patients) have been placed under quarantine and isolated medical observation, and will be sent to hospital for diagnosis and treatment once they develop symptoms. So they won't cause any spread in society," he added.