The adult prevalence of HIV in Zambia: results from a population based mobile testing survey conducted in 2013-2014.

OBJECTIVE: To estimate the adult prevalence of HIV among the adult population in Zambia and determine whether demographic characteristics were associated with being HIV positive. METHODS: A cross sectional population based survey to asses HIV status among participants aged 15 years and above in a national tuberculosis prevalence survey. Counselling was offered to participants who tested for HIV. The prevalence was estimated using a logistic regression model. Univariate and multivariate associations of social demographic characteristics with HIV were determined. RESULTS: Of the 46,099 individuals who were eligible to participate in the survey, 44,761 (97.1 %) underwent pre-test counselling for HIV; out of which 30,605 (68.4 %) consented to be tested and 30, 584 (99.9 %) were tested. HIV prevalence was estimated to be 6.6 % (95 % CI 5.8-7.4); with females having a higher prevalence than males 7.7 % (95 % CI 6.8-8.7) versus 5.2 % (95 % CI 4.4-5.9). HIV prevalence was higher among urban (9.8 %; 95 % CI 8.8-10.7) than rural residents (5.0 %; 95 % CI 4.3-5.8). The risk of HIV was double among urban dwellers than among their rural counterparts. Being divorced or widowed was associated with a threefold higher risk of being HIV positive than being never married. The risk of being HIV positive was four times higher among those with tuberculosis than those without tuberculosis. CONCLUSIONS: HIV prevalence was lower than previously estimated in the country. The burden of HIV showed sociodemographic disparities signifying a need to target key populations or epidemic drivers. Mobile testing for HIV on a national scale in the context of TB prevalence surveys could be explored further in other settings.

Changes in mobility patterns during the COVID-19 pandemic in Zambia: implications for the effectiveness of NPIs in Sub-Saharan Africa

The COVID-19 pandemic has impacted many facets of human behavior, including human mobility partially driven by the implementation of non-pharmaceutical interventions (NPIs) such as stay at home orders, travel restrictions, and workplace and school closures. Given the importance of human mobility in the transmission of SARS-CoV-2, there have been an increase in analyses of mobility data to understand the COVID-19 pandemic to date. However, despite an abundance of these analyses, few have focused on Sub-Saharan Africa (SSA). Here, we use mobile phone calling data to provide a spatially refined analysis of sub-national human mobility patterns during the COVID-19 pandemic from March 2020-July 2021 in Zambia. Overall, among highly trafficked intra-province routes, mobility decreased up to 52% from March-May 2020 compared to baseline, which was also the time period of the strictest NPIs. However, despite dips in mobility during the first wave of COVID-19 cases, mobility returned to baseline levels and did not drop again suggesting COVID-19 cases did not influence mobility in subsequent waves.

COVID-19 vaccine effectiveness during a prison outbreak when the Omicron was the dominant circulating variant, Zambia, December 2021

During a COVID-19 outbreak in a prison in Zambia from 14th to 19th December 2021, a case control study was done to measure vaccine effectiveness (VE) against infection and symptomatic infection, when the Omicron variant was the dominant circulating variant. Among 382 participants, 74.1% were fully vaccinated and the median time since full vaccination was 54 days. There were no hospitalizations or deaths. COVID-19 VE against any SARS-CoV-2 infection was 64.8% and VE against symptomatic SARS-CoV-2 infection was 72.9%. COVID-19 vaccination helped protect incarcerated persons against SARS-CoV-2 infection during an outbreak while Omicron was the dominant variant in Zambia.