Two studies, analyzing data from 14 countries in three continents, found that symptoms of long Covid occur in 25-30 per cent of people who had the acute form of the infection. One, led by John Eikelboom of McMaster University and colleagues, included 4,697 people who took part in anti-coronavirus therapy trials in 13 countries. Long Covid was detected in 25.1 per cent of them, with the most common symptoms being sleep disturbances, joint pain, fatigue and headache. The condition was more common in people from low- and middle-income countries, people of Arab/North African descent and those who required hospitalization. The results of this study are published in the journal BMJ Global Health.
Another multicenter cross-sectional study was conducted by Guoqing Qian from Ningbo University and colleagues. It involved 3,693 people who filled out questionnaires on symptoms of long Covid according to the criteria of the World Health Organization. At least one symptom was present in 30.2 percent of them, and in 10.7 percent it had a negative impact on daily life. The most common manifestations were increased fatigue, cough and expectoration of sputum. The likelihood of long Covid increased in old age, in women and with repeated infection and decreased with an increase in the number of doses of the anti-coronavirus vaccine. An article about this appeared in the journal BMC Public Health.