defects in, or deficiency of, complement components, including factor H, factor D or properdin deficiency
people with acquired complement deficiency due to receipt of complement inhibitor therapy (including but not limited to eculizumab, ravulizumab or pegcetacoplan)
functional or anatomical asplenia, including sickle cell disease or other haemoglobinopathies, and congenital or acquired asplenia
HIV, regardless of disease stage or CD4+ cell count
