Michael Ryan, the WHO's emergencies director, said there was a balance to be struck between the science and the economic and social factors.
There are eight contenders for the director general of World Trade Organization as Roberto Azevedo steps down on Monday.
Announcing the assessment, which will be presented next May, WHO chief said it should help the world understand how to prevent such crises in the future.
Top infectious diseases expert Anthony Fauci has said re-opening too soon risks triggering uncontrollable outbreaks.
IFPMA director-general Thomas Cueni said the industry was putting on an unprecedented united front to conquer the virus.
Any early release would be subject to a risk assessment from the Parole Board.
Nigel Farage described Brexit as "the greatest moment in the modern history of our great nation".
The Duke and Duchess of Sussex are bowing out entirely from representing the British monarchy, in a crisis that has shaken the centuries-old institution.
The Duke and Duchess of Sussex, rocked the monarchy on Wednesday with an announcement made without consulting any senior royals from the sovereign downwards.
Thursday's snap general election has been called in a bid to break the Brexit deadlock.
The state-run National Health Service (NHS) provides free taxpayer-funded treatment for all, which is often criticised but fiercely defended.