The PHIA Project conducts HIV-focused, cross-sectional, household-based, nationally representative surveys of adults and adolescents age 15 years and above, as well as children ages 0 to 14 years, in 13 PEPFAR countries. Participation in PHIA surveys is voluntary, and data collection consists of household interviews, individual interviews, and diagnostic testing.

Questionnaire data are collected by trained survey staff via computer-assisted personal interviews (CAPI), using Android-based tablet computers and Open Data Kit (ODK) software. Interviews are conducted in pre-selected households, where eligible participants first provide informed consent and then answer questions regarding household membership and characteristics, individual sociodemographic characteristics, and HIV-related risk factors.

Diagnostic data are collected by trained survey staff via in-home and laboratory-based testing. Venous blood (capillary blood for infants) is collected from consenting participants, followed by home-based HIV testing and counseling. Individuals who test positive for HIV are provided with in-home CD4 testing, and referred to care and treatment. All blood samples are transported to laboratory facilities for processing into plasma and freezing within 24 hours, as well as subsequent quality control testing. HIV-positive samples undergo additional analysis, including quantitative assessment of viral load, qualitative evaluation for antiretroviral metabolites, and drug resistance testing.

PHIA surveys may also include diagnostic testing for other diseases, including syphilis and hepatitis B, among others.