The World Health Organisation chief has warned "the worst is yet ahead of us" in the coronavirus outbreak as many countries ease restrictive measures aimed at reducing its spread.
WHO Director-General Tedros Adhanom Ghebreyesus did not specify why he believes the outbreak that has infected some 2.5 million people and killed more than 166,000 could get worse.
He and others, however, have previously pointed to the likely future spread of the illness through Africa, where health systems are far less developed.
"Trust us. The worst is yet ahead of us," Tedros told reporters from WHO headquarters in Geneva on Monday.
"Let's prevent this tragedy. It's a virus that many people still don't understand."
The WHO warned a large proportion of the public remains susceptible to COVID-19.
Early results from sero-epidemiologic surveys from around the world - which monitor levels of immunity within a population - suggest that a relatively small percentage of the population may have been infected, the WHO said.
WHO's technical lead for COVID-19 Maria van Kerkhove urged vigilance, saying a large proportion of the population who hadn't been infected remained susceptible.
"So that means that the virus can take off again," she said.
"And so we need to ensure that the measures that are put in place (to transition out of lockdown) are done carefully."
Some Asian and European governments have gradually eased or started relaxing lockdown measures such as quarantines, school and business closures and restrictions on public gatherings, citing a decline in the growth of COVID-19 case counts and deaths.
Tedros and his agency have been on the defensive after US President Donald Trump last week ordered a halt to his country's funding of the agency, alleging it botched the early response to the outbreak.
Trump said the WHO failed to adequately share "in a timely and transparent" way information about the outbreak after it erupted in China late last year, which Tedros disputed.
"There is no secret in WHO because keeping things confidential or secret is dangerous. It's a health issue," he said.
"This virus is dangerous. It exploits cracks between us when we have differences."
Tedros said US Centers for Disease Control and Prevention staffers have been seconded to work with his agency, suggesting that was a sign of WHO's transparency.
"Having CDC staff (at WHO) means there is nothing hidden from the US from day one" Tedros said.
"Our CDC colleagues also know that we give information immediately to anyone."
© AP 2020