Clinical management of a Nigerian patient affected by sickle cell disease with rare blood group and persistent SARS‐CoV‐2 positivity. Issue 1 (4th July 2020) - Quaresima, Micol; Quaresima, Virginia; Naldini, Matteo Maria; Cirillo, Daniela Maria; Ferrari, Angela; Mazzi, Angela; Tesini, Ester Maria Carla; Leone, Maria Cristina; Merli, Francesco