GENEVA (REUTERS) - 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 Organisation said on Friday (Oct 23).

"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.

Meanwhile, WHO is preparing its guidelines on the use of antiviral drug remdesivir to treat Covid-19, and should be able to release it in three to four weeks, the organisation's top official for clinical care responses said.

"We would anticipate that the guidelines will be available within three to four weeks," Janet Diaz told a news conference.

A WHO panel "will convene next week to look at the totality of the evidence" of the effectiveness of the drug, made by Gilead Sciences.

The US Food and Drug Administration on Thursday approved remdesivir for treating patients hospitalised with Covid-19, making it the first and only drug approved for the disease in the United States.

Remdesivir, given intravenously, was one of the drugs used to treat US President Donald Trump during his bout with Covid-19.

Remdesivir has been available under an FDA emergency use authorisation since May, after a study led by the National Institutes of Health showed it reduced hospital stays by five days. However, the WHO last week said its global trial of Covid-19 therapies found that remdesivir did not have a substantial effect on patients' length of hospital stay or chances of survival.

That study has not been reviewed by outside experts. Gilead has questioned the potential for bias in the WHO study, which was not "blinded", meaning that patients and their doctors were aware of which treatments were being used.

WHO chief scientist Soumya Swaminathan said the US FDA drug regulator does not appear to have taken the results of the global health body's study into account in giving approval.

"We believe our results are very robust," Swaminathan said.

"We hope that people who are doing treatment guidelines in other countries as well as regulators around the world will take note of our study results, in addition to the other evidence," she said. "Because you need to look at the global evidence for a drug, before you make decisions."