Geneva: The World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus has said that more research needs to be done to better understand the extent to which COVID-19 is being spread by people who don’t show symptoms.

“Since early February, we have said that asymptomatic people can transmit COVID-19, but that we need more research to establish the extent of asymptomatic transmission,” the WHO chief said at a virtual press conference on Wednesday.

“That research is ongoing, and we’re seeing more and more research being done,” he added.

Saying that the world has been achieving a lot in knowing the new virus, the WHO chief told reporters that “there’s still a lot we don’t know”, Xinhua reported.

“WHO’s advice will continue to evolve as new information becomes available,” he said.

Tedros stressed that the most critical way to stop transmission is to find, isolate, and test people with symptoms, and trace and quarantine their contacts.

“Many countries have succeeded in suppressing transmission and controlling the virus doing exactly this,” Tedros said.

Meanwhile, Michael Ryan, executive director of the WHO Health Emergencies Program, said that the COVID-19 pandemic is still evolving.

“If we look at the numbers… this pandemic is still evolving. It is growing in many parts of the world,” he said. “We have deep concerns that health systems of some countries are struggling, under a huge strain and require our support, our help, and our solidarity,” he added.