GENEVA -- The World Health Organization's emergencies chief said Friday that widespread testing for the new coronavirus is crucial and countries should not be faulted for reporting higher numbers of cases. He also appealed for a shift toward public health strategies that allow us 鈥渢o live with this virus鈥 until a vaccine emerges.

The comments from Dr. Michael Ryan suggested a change in mindset at WHO and the U.N. health agency's increased resignation that the virus first identified in China late last year will be around for a while. The number of people infected worldwide exceeded 585,000 by Friday night.

鈥淎t this point, no one can predict how long this epidemic is going to last,鈥 Ryan said during a WHO news conference. 鈥淲e are entering and moving to an uncertain future. ... Many countries around the world are just beginning the cycle of this epidemic.鈥

For weeks, WHO officials spoke during daily briefings in Geneva of a 鈥渨indow of opportunity鈥 to try to contain the spread of the virus. But lately there have been indications that the containment window has closed.

Ryan called Friday for moving from measures designed to 鈥渢ake the heat鈥 out of the pandemic to ones aimed at 鈥渕uch more precise targets, directed targets, that will allow us, at the very least, to live with this virus until we can develop a vaccine to get rid of it.鈥 A vaccine against the virus isn't expected for at least 12 to 18 months.

The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death.

WHO officials continue to caution that much remains unknown about the virus including why people who aren't elderly or have preexisting conditions become seriously ill with COVID-19.

Ryan said 10 per cent to 15 per cent of people under age 50 will have a 鈥渕oderate to severe infection.鈥

At the same time, WHO officials emphasized the importance of testing widely for the virus, saying it would enable health officials to get a better grasp on outbreaks even if increasing numbers of people testing positive may stir unease.

鈥淲e should not punish countries for getting larger numbers,鈥 Ryan said. 鈥淚f we create a situation where we overreact to the daily number, then there's a disincentive to actually test.鈥

鈥淗aving a larger number means I know where the virus is better,鈥 he said.

With the governments in many countries imposing nationwide lockdowns, WHO Director-General Tedros Adhanom Ghebreyesus acknowledged that limits on travel or leaving the house 鈥渋nfluences individual human rights.鈥

鈥淏ut this is a choice that we should make,鈥 he said. 鈥淢eaning, in order to have collective security, to be a better society and to fight the virus, we give our freedom, you know, for a while.鈥