Director-General Tedros Adhanom Ghebreyesus said countries needed to ensure they had adequate measures to control the spread of the COVID-19 before lockdown is lifted. This includes tracking systems and quarantine provision.
“The risk of returning to lockdown remains very real if countries do not manage the transition extremely carefully and in a phased approach,” he said at a virtual briefing in Geneva.
WHO epidemiologist Maria Van Kerkhove supported his concerns, explaining: “If lockdown measures are lifted too quickly, the virus can take off.”
Government-ordered lockdowns have become increasingly unpopular as time goes by.
Countries are suffering rising unemployment figures and economic activity has ground to a halt.
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The US has seen record numbers of people filing for unemployment since the outbreak hit America.
However, WHO official Mike Ryan said it was up to governments and sporting federations to decide how and when to restart.
He said WHO would offer risk management advice if needed.
The news comes as the Prime Minister prepares to update Britons on the lockdown situation on Sunday.
Boris Johnson has reportedly drafted a five-step plan to lift the UK out of lockdown over the next six months.
Mr Johnson has said the first steps will happen the next day “if we possibly can”.
However, officials fear a second wave of coronavirus or a seasonal flu outbreak this autumn could blow their plans off course.
“Nobody can quite agree what to do and when to do it. Somebody comes up with a bright idea, but the practicalities get in the way.
“We’re not South Korea.”
If all goes to plan the government will begin to relax certain restrictions as early as Monday, the Mirror reported.
According to the publication, unlimited exercise will be allowed from Monday.
From Monday employees are set to be encouraged to return to workplaces that have stayed open throughout the lockdown if it is deemed safe to do so.
Garden centres could also reopen.
However, there may be more guidance on the use of outdoor spaces including open-air markets, high streets and cemeteries.
By the end of May or beginning of June schools may begin the process of reopening starting with year six.
Households could also be allowed to expand “social bubble” to meet one other household of family or friends.