They include wearing face coverings, social distancing, hand-washing and testing.
Asked about the USA outbreak, which White House coronavirus experts say is entering a "new phase", he said officials seemed to have set out the "right path" and it was not the WHO's job to do so.
Speaking on Sunday, August 2, World Health Organization director-general, Tedros Adhanom Ghebreyesus, said there may not be a "silver bullet" when the vaccines come out as many countries have been savaged.
A number of vaccines for the novel coronavirus have already reached various clinical trial stages but, according to the World Health Organization, only six projects have got to phase three, which is an efficacy test with thousands of human subjects.
"We have seen around the world, that it's never too late to turn this pandemic around, " he said. The rules also apply to foreigners who enter Belgium for at least 48 hours. "There are concerns that we may not have a vaccine that may work, or its protection could be for just a few months, not more".
Meanwhile, some 30,000 volunteers are taking part in a large-scale trial of an experimental vaccine in the U.S. which got under way last Monday.
Dr Ryan said countries with high transmission rates, including Brazil and India, needed to brace for a long battle.
The WHO leader also announced during the briefing that an advanced team in China studying the origins of COVID-19 has recently concluded its groundwork. The mission, demanded by the United States, was to search and identify the start of the virus.
"Once you understand where that the barrier was breached, then you move into the studies in a more systematic way on the animal side", The WHO press office, contacted by The Associated Press after the news conference, did not provide details of the terms of reference, say whether they would be made public, or indicate how big the global team would be or when it could be sent to China.
At the time of COVID-19, especially when there is disruption to health services; WHO recommends that mothers with suspected or confirmed COVID-19 should be encouraged, the same as all other mothers, to initiate or continue to breastfeed.
Ryan said China had already given some information but knowledge gaps remained.
Michael Shields and Emma Farge reported on this story for Reuters. Hai Do was the editor.
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