The world is now at a critical juncture in the COVID-19 pandemic and some countries are on a dangerous path, facing the prospect of health services collapsing under the strain, the head of the World Health Organization said on Friday.

"We are at a critical juncture in the COVID-19 pandemic, particularly in the Northern hemisphere," WHO Director-General Tedros Adhanom Ghebreyesus told a news conference. "The next few months are going to be very tough and some countries are on a dangerous track."

"We urge leaders to take immediate action, to prevent further unnecessary deaths, essential health services from collapsing and schools shutting again. As I said it in February and I'm repeating it today: This is not a drill."

Tedros said too many countries were now seeing an exponential increase in infections, "and that is now leading to hospitals and intensive care units running close or above capacity -- and we're still only in October".

He said countries should take action to limit the spread of the virus quickly. Improving testing, tracing of contacts of those infected and isolation of those at risk of spreading the virus would enable countries to avoid mandatory lockdowns.