Clinical characteristics of COVID-19
The clinical scenarios of COVID-19 are diverse and range from asymptomatic to critical illness and even fatal outcomes5. The symptoms of COVID-19 include dry cough, fatigue, fever, myalgia, headache, diarrhea, and even respiratory failure1. Olfactory and gustatory dysfunctions have been also identified as distinct symptoms of SARS-CoV-2 infection, especially in the western countries13. Thus, the respiratory symptoms of COVID-19 may be confused with those of allergic rhinitis (AR) and the common cold14. Skin manifestations of COVID-19 include vesicular, urticarial, and maculopapular eruptions and livedo, necrosis, and other vasculitis forms15 and are more common among European and North Americans than among Asians16. The heterogeneity of COVID-19 warrants the elucidation of the phenotypes and endotypes of COVID-19 that will benefit from precision medicine17,18. In addition, persistent symptoms such as fatigue, brain fog, body aches, and loss of smell may persist for months following acute infection and are referred as post-acute COVID-19 syndrome or long-COVID19,20. After a 1-year follow-up, most COVID-19 recovered patients regain their physical and functional status, although it remains lower than individuals without infection21.
Children at all ages appear to be susceptible to SARS-CoV-2 infection, although most of them are asymptomatic or develop mild symptoms22. Multisystem inflammatory syndrome in children (MIS-C) has been described in COVID-19 patients with an overall 2% mortality23. MIS-C predominantly affects children between 6 and 12 years. Most MIS-C children were critically ill, mostly from shock and/or left ventricular dysfunction, with less severe or no respiratory involvement24. Regarding the treatment of MIS-C, intravenous immune globulin (IVIG) plus glucocorticoids was associated with a lower risk of cardiovascular dysfunctions but not the recovery from disease when compared to IVIG treatment alone25,26.