Two studies analyzing data from 14 countries in three continents found that symptoms of long-term COVID-19 occur in 25–30 percent of those who recovered from the acute form of the infection. One of these studies, conducted by John Eikelboom of McMaster University and colleagues, included 4,697 people participating in anti-coronavirus therapy trials in 13 countries. Long-term COVID-19 was detected in 25.1 percent of them, with the most common symptoms being sleep disturbances, joint pain, fatigue, and headache. This condition was more common among residents of low- and middle-income countries, people of Arab/North African descent, and those requiring hospitalization. The results of this study were published in the journal BMJ Global Health.
Another multicenter, cross-sectional study was conducted by Guoqing Qian of Ningbo University and colleagues. They included 3,693 people who completed questionnaires on symptoms of long-term COVID-19 according to the World Health Organization criteria. At least one symptom was present in 30.2 percent of them, with 10.7 percent experiencing a negative impact on daily life. The most common symptoms were increased fatigue, cough, and sputum production. The risk of long-term COVID-19 increased with older age, women, and reinfection, and decreased with increasing doses of the coronavirus vaccine. The study was published in the journal BMC Public Health.
