A study has found that 32% of people who tested positive for SARS-CoV-2 were still experiencing at least one symptom 6 weeks after their tests. The most common of these symptoms were fatigue, shortness of breath, and a loss of taste or smell.
People with relatively mild COVID-19 usually recover within 2–3 weeks of the symptoms arising.
However, many have reported debilitating symptoms that last for weeks or months, a health issue called long COVID. Common symptoms include breathlessness, a cough, heart palpitations, exercise intolerance, fatigue, difficulty concentrating, and brain fog.
Those who were never formally diagnosed with COVID-19 can have particular difficulty convincing healthcare professionals that they have long COVID.
The phenomenon appears to be more common among people who experienced more severe infections.
One study of people hospitalized with COVID-19 in Italy found that 87.4% reported experiencing at least one symptom, often fatigue or shortness of breath, 2 months after discharge.
Among people with milder infections, however, the prevalence of long COVID has been unclear. Data from the COVID Symptom Study app suggest that 1 in 10 people with the illness experience symptoms for 3 weeks or more.
Now, researchers in Switzerland have found that as many as 1 in 3 people who had milder COVID-19 were still experiencing symptoms after 6 weeks.
Their findings have been published in Annals of Internal Medicine.
Doctors and epidemiologists led by a team from Geneva University Hospitals followed up with 669 people who had tested positive for SARS-CoV-2. Most, 69%, had no underlying risk factors for the illness.
The participants’ average age was 42.8 years, and 60% were female. Over the course of the study, 40 people required hospitalization.
Healthcare professionals interviewed most of the participants by phone every 48 hours for the first 10 days after their diagnoses. They asked a standardized list of questions about symptoms.
If a person reported worsening symptoms, they received these calls every 24 hours. All participants were interviewed again between 30 and 45 days after their diagnosis.
At an average of 43 days, or 6 weeks, after diagnosis, at least 32% of all the participants reported that they were still experiencing at least one symptom of COVID-19.
The most commonly reported were fatigue, experienced by 14% of the participants, shortness of breath (9%), and a loss of taste or smell (12%). A further 6% reported a persistent cough, and 3% reported headaches.
“This has enabled us to better understand the evolution of the disease in people who generally suffer neither from specific risk factors nor from a serious form of the disease,” says study co-author Dr. Idris Guessous.
“In addition to the physical distress of their symptoms, many were very worried: How much longer would it last? Were some after-effects irrecoverable?” adds Dr. Mayssam Nehme, the co-lead author of the study.
The team call on healthcare providers, employers, insurance companies, and wider society to recognize that previously healthy people can experience the after-effects of COVID-19 for weeks or even months after developing the underlying infection.
In their paper, the authors conclude:
“Recognizing the persistence of symptoms could legitimize patients’ concerns in an unknown and new disease. Adequate communication can provide reassurance, reduce anxiety, and potentially optimize recovery.”
The researchers will continue to follow up with their study population for 3, 7, and 12 months after diagnosis.
They acknowledge some limitations to their published research. In particular, several people stopped participating during the follow-up, which could have led to ascertainment bias in the final results.
For example, people who experienced lingering symptoms may have been more willing to take part in the later stages of the study than those who had fully recovered.
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