Geneva, Mar 4 (IANS): Different from SARS, MERS or influenza, COVID-19 is "a unique virus with unique characteristics," the chief of the World Health Organization (WHO) said here on Tuesday.

"We are understanding this virus and the disease it causes more and more," said WHO Director-General Tedros Adhanom Ghebreyesus.

COVID-19 does not transmit as efficiently as influenza, according to the data collected so far, Tedros said, noting those people who are infected but not sick are not major drivers of COVID-19 transmission, the Xinhua news agency reported.

He stressed that evidence from China showed that most of the reported cases develop symptoms within two days and only one percent have no symptoms.

The ongoing studies on examing COVID-19 antibodies in large numbers of people will provide further insight into the extent of infection in populations over time, said Tedros.

Although no vaccine and no specific treatment are available for COVID-19 so far, Tedros noted that more than 20 vaccines are in development globally, and several therapeutics are in clinical trials.

Tedros reiterated that COVID-19, rather than seasonal flu, can be contained by a comprehensive approach.

He urged countries to adapt their existing healthcare systems to contain COVID-19. "They are not starting from scratch," he said.