Coronavirus lockdowns being lifted only for the virus to break out again is the “last thing” that countries need, the head of the World Health Organization warned Wednesday.

Director-General Tedros Adhanom Ghebreyesus said the current lockdowns provide countries a “second window of opportunity” to tackle outbreaks.

“We understand that these countries are now trying to assess when and how to ease these measures,” Tedros said at a press briefing. “The answer depends on what countries do while these wide measures are in place.”

Tedros said the countries need to implement measures such as expanding and training the health workforce, as well as ramping up the speed and production of testing before considering ending lockdowns.

“These measures are the best way to suppress and stop transmission so that when restrictions are lifted, the coronavirus doesn’t resurge,” he said. “The last thing any country needs is to open schools and businesses, only to be forced to close them again because of a resurgence.”

COVID-19 has spread now to more than 450,000 people worldwide with the death toll climbing past 20,000, according to the latest figures from Johns Hopkins University.