Women aged 50-60 are at greatest risk of developing “long Covid”, analysis suggests. Older age and experiencing five or more symptoms within the first week of illness were also associated with a heightened risk of lasting health problems.
The study, led by Dr Claire Steves and Prof Tim Spector at King’s College London, analysed data from 4,182 COVID Symptom Study app users who had been consistently logging their health and had tested positive for the virus.
In general, women were twice as likely to suffer from Covid symptoms which lasted longer than a month, compared with men – but only until around the age of 60, when their risk level became more similar.
Increasing age was also associated with a heightened risk of long Covid, with about 22% of people aged over 70 suffering for four weeks or more, compared with 10% of 18- to 49-year-olds.
For women in the 50-60 age bracket, these two risk factors appeared to combine: They were eight times more likely to experience lasting symptoms of Covid-19 compared with 18- to 30-year-olds. However, the greatest difference between men and women was seen among 40- to 50-year-olds, where women’s risk of developing long Covid was double that of men’s.
“This is a similar pattern to what you see in autoimmune diseases,” said Spector. “Things like rheumatoid arthritis, thyroid disease and lupus are two to three times more common in women until just before menopause, and then it becomes more similar.” His guess is that gender differences in the way the immune system responds to coronavirus may account for this difference.
The study, which was published as a preprint and has not yet been peer reviewed, also found that experiencing five or more symptoms during the first week of developing Covid-19 was associated with a heightened risk of lasting health problems.
Here too, differences in the immune response may be involved: “There’s certainly a group of long Covid sufferers that have this multi-system immune–like disease, where they get gastrointestinal problems, skin rashes, nerve problems and brain fog – so the whole body is involved rather than just one bit,” said Spector. Probably, the immune system is working differently in such people, which may manifest as symptoms in multiple body systems being experienced from week one.
Other factors which the study associated with heightened risk of developing lasting Covid-19 symptoms included being overweight, or having asthma.