The World Health Organization called Tuesday for greater research, recognition and rehabilitation for Long Covid sufferers as it brought experts together to share insights into the little-understood condition.
The WHO held the first in a planned series of seminars aimed at expanding understanding of post-Covid conditions, which heard not only from scientists and doctors but also from sufferers themselves.
Little is known about why some people, after coming through the acute phase of Covid-19, struggle to recover and suffer ongoing symptoms including tiredness and brain fog as well as cardiac and neurological disorders.
Studies suggest that potentially one in 10 cases may have prolonged symptoms one month after infection -- meaning millions may be suffering from ongoing illness.
WHO director-general Tedros Adhanom Ghebreyesus said that with attention turning in the coronavirus pandemic towards vaccination campaigns, "Long Covid should not fall through the cracks".
He said the impact of Long Covid on society and the economy was starting to become clear, and for those reasons, "people start to listen" beyond the medical community.
Though the level of research is growing, it is "still not enough", he said.
British doctor Gail Carson, from the International Severe Acute Respiratory and Emerging Infection Consortium, warned that "Long Covid could become the pandemic on the pandemic".
Presenting findings from a post-Covid support forum, she raised the plight of under-the-radar sufferers.
Even for many who never had to be hospitalised with the virus, their condition "has been life changing".
"People are losing jobs, they're losing relationships. There's a real urgency to try and understand this," she said.
Carson said that Long Covid in children was "even less well recognised or counted" than it is in adults.
She said it was "staggering" that only 45 out of more than 5,000 funded Covid-19 projects were looking at Long Covid.
Maria Van Kerkhove, the WHO's technical lead on Covid-19, said the organisation was continuing to learn about this aspect of the pandemic.
"We know that much more work needs to be done," she said.
"We need to show compassion with each other but we also need to be persistent in getting to the answers."