MAHUOB, Abdulaleem; ALKHALI, Khaled; IRAWATI, Lyna. COVID-19 Pandemic: Factors Contributing to Persistent Infection and Severe Cases . Journal of 21 September university for medical and applied sciences, Sana,a Yemem, v. 5, n. 1, p. 1–15, 2026. DOI: 10.65693/j21umas.2026.v5i1.369. Disponível em: https://ojs.21umas.edu.ye/masj/article/view/369. Acesso em: 15 sep. 2026.