Many patients with long Covid have been unable to return properly to work six months after infection, a study suggests.
New research examined the impact on people months after their initial infection.
While some seemingly return to normal health, others are left with debilitating fatigue and so-called "brain fog" among other symptoms.
The study, which has not yet been peer-reviewed, examined symptoms as well as other factors.
Researchers from Patient-Led Research for Covid-19 conducted a survey of more than 3,700 long Covid patients from 56 different countries.
A third were in their 40s, 27% in their 50s and 26% were aged 30 to 39. The majority of respondents (79%) were women.
Just 8% were admitted to hospital for their Covid symptoms and only a quarter reported a lab-confirmed case of Covid-19.
Most (96%) reported that their symptoms lasted more than 90 days.
The paper, published as a pre-print on MedRxiv, found that symptoms affected 10 different "organ systems".
The most frequent symptoms reported after six months were fatigue, cognitive dysfunction and post-exertional malaise – the worsening of symptoms following even minor physical or mental exertion.
Those who reported symptoms six months after infection reported that they experienced relapses which were often triggered by exercise, physical or mental activity and stress.
Overall, 45% of people living with long Covid had a "reduced" work schedule compared with pre-illness.
And 22.3% were not working due to their health conditions.
"Patients with Long Covid report prolonged multisystem involvement and significant disability," the researchers wrote.
"Most had not returned to previous levels of work by six months.
"Many patients are not recovered by seven months, and continue to experience significant symptom burden."