Mesenchymal stem cells for medical purposes for use in the treatment and prevention of Covid-19 and Coronaviruses; Pharmaceutical preparations for human use, namely, Mesenchymal stem cells for medical or clinical use for the treatment and prevention of Covid-19 and Coronaviruses; Pharmaceutical preparations featuring Mesenchymal stem cells for the treatment and prevention of infectious diseases, namely, COVID-19 and Coronaviruses