Geneva, Switzerland --- The quest to unravel the mysteries behind Long COVID took a step forward on Thursday with the launch of an internationally coordinated attempt to capture standardized data on the condition.

The World Health Organization and the International Severe Acute Respiratory and Emerging Infection Consortium announced a project to amass a so-called core outcome set (COS) to help build up a better picture of post-COVID conditions.

In a statement via the WHO, ISARIC said Long COVID, which remains one of the lesser-understood aspects of the pandemic, was an "emerging global healthcare crisis"

Little is known about why some people, after coming through the acute phase of infection, struggle to recover and suffer ongoing symptoms including shortness of breath, extreme fatigue and brain fog as well as cardiac and neurological disorders.

Despite a "significant portion" of COVID-19 cases going on to suffer from Long COVID, "the evidence for this condition is limited and based on small patient cohorts with short-term follow-up," ISARIC said.

"There is an urgent need for the development of a COS to optimize and standardize clinical data collection and reporting across studies (especially clinical trials) and clinical practice for this condition."

An international group of COS and post-COVID experts have put together a research program alongside the WHO and ISARIC, the statement said.

The project, entitled Post-COVID Condition Core Outcomes, will start by surveying people living with Long COVID.

The first phase, to be completed in the coming months, will focus on what outcomes should be measured; the second, to be completed in 2022, will look at how to measure these outcomes.

Unknown number of sufferers

Nearly 205 million cases of coronavirus have been registered since the outbreak emerged in China in December 2019, according to a tally from official sources compiled by AFP.

The true figure, including unrecorded cases, will be far higher, while the number of people suffering from Long COVID is simply unknown.

The WHO said last week it was working to have better rehabilitation programs for Long COVID sufferers.

The organization has held a series of seminars this year aimed at expanding understanding of post-COVID conditions, hearing not only from scientists and doctors but also directly from sufferers themselves.

Janet Diaz, the WHO's lead on Long COVID, said last week there had been more than 200 reported symptoms.

Diaz said some patients had symptoms that dragged on from the acute phase; others got better and then relapsed, with conditions that could come and go; while others had symptoms that only appeared after recovering from the acute phase.

A small proportion of patients suffer symptoms for nine months and even longer.