- An analysis of Covid-19 patient data may predict who is likely to experience long-lasting illness.
- The study was based on the responses of more than 4 000 people.
- Symptoms, age, sex, and BMI were shown to be strong predictors of long Covid.
One in 20 people infected with Covid-19 is estimated to remain sick for at least eight weeks, a new study suggests.
Known by the unofficial medical term "long Covid" (also known as "long haul"), it involves cases in which patients suffer from symptoms of the illness for longer than the official World Health Organisation-endorsed two-week period.
Researchers from King's College London (KCL), whose study was published in medRxiv and is still awaiting peer review, analysed more than 4 000 Covid-19 patients across Sweden, the UK, and the US. They were asked to record their symptoms in a Covid Symptom Study app.
They found that older people, women, and those who experienced more than five symptoms during their first week of illness were more likely to develop long Covid.
The following five symptoms were identified as predictors of long Covid: fatigue, headache, difficulty breathing, a hoarse voice, and muscle or body aches.
These findings could serve as a warning and identify Covid-19 patients who need extra care.
The responses showed that around 20% of people reported that they did not feel better four weeks later. By eight weeks, around 190 patients reported lingering symptoms, and by 12 weeks, close to 100 patients said they hadn't recovered yet.
Almost 98% of patients who have long Covid reported fatigue, and 91% reported a headache. Around two-thirds of respondents said they had experienced muscle or body aches, and the same number said they had difficulty breathing. About 58% reported developing headaches.
"It's important we use the knowledge we have gained from the first wave in the pandemic to reduce the long-term impact of the second," the study's lead author, Dr Claire Steves, said in a university news release.
"Thanks to the diligent logging of our contributors so far, this research could already pave the way for preventative and treatment strategies for long Covid."
Other factors that predict long-Covid
Apart from the symptoms, age was also a strong predictor of long Covid. About 22% of respondents were aged 70 years and older, compared to 10% of respondents, who were between the ages of 18 and 49 years.
Body mass index (BMI) also played a role, the researchers noted, with a higher BMI showing a higher likelihood of developing long Covid.
Women in younger age groups were also found to be more likely to be long-haulers – a surprising finding, as men have been shown to be affected more severely by Covid-19 than women. Although sex was not a very strong predictor, they said.
However, the trend could possibly be explained by the fact that more women logged their symptoms onto the app.
"I've had the same experience where many more women who have long-term symptoms took my survey than men by a huge margin," Natalie Lambert, an associate professor of medicine at Indiana University, who wasn't involved in the study, told Business Insider US.
"Is it because more women are experiencing long-term symptoms? Is it because women are more likely to take these surveys and share their health experiences? We won't really know until we get enough data about everybody."
Professor Tim Spector, a professor of genetic epidemiology from KCL and co-author of the study, also commented that while Covid-19 might be a mild illness for most people, for one in 50 people, symptoms can persist for longer than 12 weeks.
"So it's important that, as well as worrying about excess deaths, we also need to consider those who will be affected by long Covid if we don't get the pandemic under control soon.
"As we wait for a vaccine, it is vital that we all work together to stem the spread of coronavirus, via lifestyle changes, and more rigorous self-isolating with symptoms or positive tests," he said.