The World Health Organization on Thursday urged national authorities to make a priority of understanding the consequences of long-term coronavirus infections to help those suffering from worrying symptoms after many months.

"It's a clear priority for WHO, and of the utmost importance. It should be for every health authority," Hans Kluge, regional director for WHO Europe, told a press conference.

While some studies have begun to shed light on the illness, it is still unclear why some patients with Covid-19 continue to show symptoms for months, including tiredness, brain fog, and cardiac and neurological disorders.

"The burden is real and it is significant. About one in 10 Covid-19 sufferers remain unwell after 12 weeks, and many for much longer," Kluge said.

According to WHO Europe, about a quarter of Covid-19 patients suffer from symptoms four to five weeks after testing positive.

Noting that reports of long-term symptoms came soon after the disease was first discovered, Kluge said that some patients were "met with disbelief or lack of understanding".

He stressed that those patients "need to be heard if we are to understand the long-term consequences and recovery from Covid-19".

Speaking at the same press conference, professor Martin McKee of the European Observatory on Health Systems and Policies acknowledged that much of the knowledge of the condition was the result of mystified sufferers reaching out and connecting the dots themselves.

"We owe a debt to those who were suffering... who came together to raise awareness of this condition," McKee said.

WHO Europe called on European countries and institutions to "come together as part of an integrated research agenda", coordinating their data collection tools and study protocols.

The regional director also said he would bring together the 53 member countries of the WHO's European region, including several countries in Central Asia, "to set out a regional strategy".

In early February, WHO organised the first virtual seminar devoted to so-called "Long Covid", in order to properly define it, give it a formal name and coordinate methods for studying it.

On Thursday, the regional branch also published a policy brief for member states calling for, among other things, the creation of appropriate services for recovering Covid sufferers, such as rehabilitation and online support tools.

The brief also called for governments to tackle "the wider consequences of post-Covid conditions" such as employment rights, sick pay policies, and access to disability benefits.