Abstract
Background: Long-term suppression of SARS-CoV-2 transmission will require context-specific strategies that recognize the heterogeneous capacity of communities to undertake public health recommendations, particularly due to limited access to food, sanitation facilities, and physical space required for self-quarantine or isolation. We highlight the epidemiological impact of barriers to adoption of public health recommendations by urban slum populations in low- and middle-income countries (LMICs) and the potential role of community-based initiatives to coordinate efforts that support cases and high-risk contacts.
Methods: Daily case updates published by the National Public Health Institute of Liberia were used to inform a stratified stochastic compartmental model representing transmission of SARS-CoV-2 in two subpopulations (urban poor versus less socioeconomically vulnerable) of Montserrado County, Liberia. Differential transmission was considered at levels of the subpopulation, household versus community, and events (i.e., funerals). Adoption of home-isolation behavior was assumed to be related to the proportion of each subpopulation residing in housing units with multiple rooms, access to sanitation facilities, and access to basic goods like water and food. Percentage reductions in cumulative infection counts, cumulative counts of severe cases, and maximum daily infection counts for each subpopulation were evaluated across intervention scenarios that included symptom-triggered, community-driven efforts to support high-risk contacts and confirmed cases in self-isolation following the scheduled lifting of the state of emergency.
Results: Modeled outbreaks for the status quo scenario differed between the two subpopulations, with increased overall infection burden but decreased numbers of severe cases in the urban poor subpopulation relative to the less socioeconomically vulnerable population after 180 days post-introduction into Liberia. With more proactive self-isolation by mildly symptomatic individuals after lifting of the public health emergency, median reductions in cumulative infections, severe cases, and maximum daily incidence were 7.6% (IQR: 2.2%-20.9%), 7.0% (2.0%-18.5%), and 9.9% (2.5%-31.4%) for cumulative infections, severe cases, and maximum daily incidence, respectively, across epidemiological curve simulations in the urban poor subpopulation and 16.8% (5.5%-29.3%), 15.0% (5.0%-26.4%), and 28.1% (IQR: 9.3%-47.8%) in the less socioeconomically vulnerable population. An increase in the maximum attainable percentage of behavior adoption by the urban slum subpopulation, with the provision of support to facilitate self-isolation or quarantine, was associated with median reductions in cumulative infections, severe cases, and maximum daily incidence were 19.2% (IQR: 10.1%-34.0%), 21.1% (IQR: 13.3%-34.2%), and 26.0% (IQR: 11.5%-48.9%), respectively, relative to the status quo scenario.
Conclusions: Broadly supported post-lockdown recommendations that prioritize proactively monitoring symptoms, seeking testing and isolating at home by confirmed cases are limited by resource constraints in urban poor communities. Investing in community-based initiatives that determine needs and coordinate needs-based support for self-identified cases and their contacts could provide a more effective, longer-term strategy for suppressing transmission of COVID-19 in settings with prevalent distrust and socioeconomic vulnerabilities.
Coordinated support for local action: Modeling strategies to facilitate behavior adoption in urban-poor communities of Liberia for sustained COVID-19 suppression
