2.1 Study design and setting
This was a cross-sectional study that included 164 individuals who were
rejected for blood donation at the Instituto Nacional de Sangue (INS), a
reference health unit, located in Luanda, the capital city of Angola,
between March to May 2022. The study was carried out at Centro de
Investigação em Saúde de Angola (CISA), a research institution supported
by the Instituto Nacional de Investigação em Saúde (INIS), also located
in Luanda. The INIS is a public institution of the Angolan Ministry of
Health (MoH), which develops research in the most diverse areas of
health and its determinants, to contribute to the strengthening of
public health policies in Angola. This study was approved by the
National Ethics Committee of the Angolan MoH (nr. 39/2021) and the
direction board of the INS (nr.128/GDG/INS/2022). Participants were
informed about the objectives of the study and verbal consent was
obtained from all enrolled even before they were considered part of the
study.