MEASLES AND RUBELLA SEROLOGICAL SURVEILLANCE IN ZAMBIA: DESIGN, IMPLEMENTATION, AND ANALYSIS

Measuring population immunity to infectious diseases is an important metric to assess the potential for outbreaks and target interventions. Vaccination coverage is typically used to approximate population immunity levels, but the most direct measure is to collect biospecimens and test antibody levels in the population. This method of conducting serological surveillance can monitor progress towards measles and rubella elimination and flag immunity gaps to target for vaccination. Serosurveys have been conducted for both measles and rubella viruses, primarily in developed countries due to the costs, logistics, laboratory requirements, and analysis techniques that make serological surveillance complex. This dissertation addresses serosurvey design topics including community acceptance, cost estimates, and data analysis issues when estimating seroprevalence from different survey designs. We use the context of two serosurveys conducted to monitor population immunity before and after a measles-rubella vaccination campaign in Zambia. First, we evaluated barriers and facilitators to serosurvey participation using quantitative and qualitative data. Qualitative data from data collectors who participated in a measles-rubella serosurvey and caregivers at health facilities identified interpersonal relationships and serosurvey design issues as key barriers and facilitators to participation. Provision of information ahead of the serosurvey to answer questions related to blood collection and communicating through a trusted source, such as the community health worker, were particularly important. In the second aim, we captured the cost of implementing serosurveys. We estimated that up to two-thirds of costs could be saved by nesting a serosurvey in an already planned vaccination coverage survey. Identifying what contributes to serosurvey costs can help identify ways to reduce cost to make them more accessible to low- and middle-income countries. Finally, in the third aim we evaluated the impact of the vaccination campaign in Southern province, Zambia. The pre and post-campaign serosurveys demonstrated significant increases in seroprevalence of antibodies to measles and rubella, highlighting the impact of the vaccination campaign. Comparing the serosurveys required survey weighting and direct adjustments to account for selection bias, specimen types and laboratory test kits. Characterizing the acceptability, cost and analytic challenges can help improve the design and implementation of serological surveys to meet programmatic goals