While monitoring of HIV prevalence among

While monitoring of HIV prevalence among pregnant women attending antenatal clinics has
consistently been the main approach for surveillance, countries have used different approaches to
select the antenatal clinic sites. Most countries have selected one or two sites in the majority of
the nation’s provinces or regions. Often one site is in the regional capital, the second site in a
semi-urban area within the same region or province. The surveillance systems in Ethiopia, Ghana,
Kenya, Nigeria, and Uganda are examples of this approach. Tanzania uses a similar system but
selected six of the country’s 20 regions for surveillance and established four sites in each region.
The surveillance system in Cote d'Ivoire also covers all regions with one urban site, but in four
regions three smaller rural clinics are included. While the urban site include 300 pregnant women
in a surveillance round, each of the three rural sites aims for a sample size of 100. The combined
data from the three clinics make up a rural site with 300 women. Countries like Botswana,Lesotho, Swaziland have selected clinics located in a city/large town as well as nearby smaller
health facilities in the same district to constitute a "sentinel site". South Africa uses probability
proportional to size sampling to select sentinel sites with each public health facility ion the
province acting as a sampling unit with about 400 sites participating in each round of survey.
Each site enrols a minimum of 40 pregnant women.