Article human 244 female 208 male 208 adult 182 Humans 179 controlled study 159 major clinical study 148 Female 127 Male 123 middle aged 109 aged 92 Middle Aged 86 Adult 78 disease severity 61 Aged 57 Severity of Illness Index 55 severity of illness index 55 body mass 53 priority journal 48 clinical article 44 cohort analysis 44 questionnaire 41 risk factor 40 follow up 38 adolescent 37 retrospective study 37 cross-sectional study 36 coronavirus disease 2019 32 child 31