The study says nothing about the symptoms being psychological. It says that people who self-diagnosed as having COVID-19 attributed those symptoms to COVID-19 w

The study says nothing about the symptoms being psychological. It says that people who self-diagnosed as having COVID-19 attributed those symptoms to COVID-19 whether or not they showed antibodies for the virus. The symptoms and symptom clusters mentioned - like fatigue, body ache, breathlessness, headache, and strained attention or focus - have many causes both physical and psychological. What the study is saying is that people think they've had COVID-19 because they experience these symptoms or that they've had these symptoms in addition to COVID-19 and have perhaps mistakenly attributed these symptoms to the disease. In the words of the article itself, from the Discussion section: Two main mechanisms may account for our findings. First, having persistent physical symptoms may have led to the belief in having had COVID-19, especially in the context of a growing concern regarding long COVID. Although adjusting for self-rated health before the pandemic did not affect our results, another disease may underlie symptoms attributed to COVID-19 infection. Second, the belief in having had COVID-19 infection may have increased the likelihood of symptoms, either directly by affecting perception19,20 or indirectly by prompting maladaptive health behaviors, such as physical activity reduction or dietary exclusion. These mechanisms are thought to contribute to the long-described persistence of physical symptoms after acute infections.