This study evaluates the impact of Zimbabwe's program for the prevention of mother-to-child HIV transmission (PMTCT) on vertical transmission of HIV infection and HIV-free survival among infants exposed to HIV. The study will test the hypothesis that the accelerated PMTCT program in Zimbabwe will result in fewer new HIV infections in infants and will increase infant survival.

The World Health Organization (WHO) recommends that all pregnant women receive antiretroviral therapy (ART) during pregnancy and breastfeeding ("Option B") or ideally throughout their lives regardless of clinical stage ("Option B+"). In February 2013, Zimbabwe's Ministry of Health and Child Welfare (MoHCW) declared that Zimbabwe would begin implementing Option B+ in October of 2013. This impact evaluation utilizes serial population-based, community-level surveys to comprehensively assess the prevention of mother-to-child HIV transmission strategy (PMTCT) 'Option B+' among mother-infant pairs in Zimbabwe. The investigators will assess the population-level impact of Option B+ in Zimbabwe using serial community-based cross-sectional serosurveys with data from three time points: 2012 (pre-Option A standard of care), 2014 (post-Option A / pre-Option B+), and 2017 (post Option B+ implementation) in order to monitor population-level trends in MTCT and HIV-free infant survival.

The investigators will compare outcomes among infants from 2017 to outcomes among mother-infant pairs who participated in similar surveys conducted in 2012 and 2014. These community-level data, along with in-depth facility survey data, will also allow the investigators to examine impact heterogeneity by the extent of integration of PMTCT and ART services at the facility. Together with effectiveness data from the serosurveys, facility-level resource utilization and cost data will allow assessment of Option B+ cost-effectiveness. In addition, this study will also include a population-based, community-level survey conducted in 2017 to assess retention of mothers in ART services after weaning (19-36 months postpartum). These data will allow the investigators to assess HIV-infected mothers' retention in care at the time of the survey, when most mothers will have stopped breastfeeding

Inclusion Criteria Mothers-Infant pairs:

• Mother or caregiver is 16 years of age or older
• Delivered or provides care for an infant (alive or deceased) who is or who would have been 9-18 months of age at the time of the survey
• Able and willing to provide written informed consent

Exclusion Criteria Mothers-Infant pairs:

• Mother or caregiver is younger than 16 years of age
• Infant (alive or deceased) is not/would not have been 9-18 months of age at the time of the survey

Inclusion Criteria Mothers/Caregivers:

• At least 16 years of age or older
• Delivered an infant (alive or deceased) who is or who would have been 19-36 months of age at the time of the survey
• Able and willing to provide written informed consent

Exclusion Criteria Mothers/Caregivers:

• Mother or caregiver is younger than 16 years of age
• Infant (alive or deceased) is not/would not have been 19-36 months of age at the time of the survey

Inclusion Criteria Healthcare Staff:

• At least 18 years of age or older
• Currently providing PMTCT services at one of the 157 selected facilities
• Able and willing to provide written informed consent

Exclusion Criteria Healthcare Staff:

• Health care staff is younger than 18 years of age
• Health care staff is not currently providing PMTCT services at one of the 157 selected facilities

Inclusion Criteria Providers:

• At least 18 years of age or older
• Currently providing ANC or ART care directly to clients at one of the 20 purposefully selected facilities
• Splitting time as a provider between one or more of the following HIV services: HIV testing and counseling (HTC), prevention of mother-to-child transmission (PMTCT), and male circumcision (MC)
• Able and willing to provide written informed consent

Exclusion Criteria Providers:

• Provider is younger than 18 years of age
• Currently not providing ART care directly to clients at one of the 20 purposefully selected facilities
• Does not split time as a provider between one or more of the following HIV services: HIV testing and counseling (HTC), prevention of mother-to-child HIV transmission (PMTCT), and male circumcision (MC)

Inclusion Criteria Patients:

• At least 18 years of age or older
• Received HIV testing and counseling (HTC), prevention of mother-to-child HIV transmission (PMTCT), or male circumcision (MC) services at one of the 20 purposefully selected facilities on the day of the interview
• Able and willing to provide verbal consent

Exclusion Criteria Patients:

• Patient is younger than 18 years of age
• Did not receive HIV testing and counseling (HTC), prevention of mother-to-child HIV transmission (PMTCT), or male circumcision (MC) services at one of the 20 purposefully selected facilities on day of interview

All study participants will be enrolled from 157 health facilities and health facility catchment areas in Harare, Mashonaland West, Mashonaland Central, Manicaland, and Matabeleland South provinces in Zimbabwe. In Zimbabwe, the catchment area of a health facility has a radius of approximately 10 km (allowing for variation due to geography).

Healthcare staff, providers, and patients will be sampled from health facilities, while mother-infant pairs and mothers/caregivers will be sampled from health facility catchment areas.