CD4 and infection: When the CD4+ T-cell count falls below 200 cells/uL, a person is at increased risk of opportunistic infections and malignancies (Egger et al., 2002; Institute of Medicine (US) Committee on Social Security HIV Disability Criteria, 2010; Opportunistic Infections Project Team of the Collaboration of Observational Hiv Epidemiological Research in Europe (Cohere) in EuroCoord, Young et al., 2012; Merci et al., 2017).