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CAPS Methods Core Presents: How far will it be necessary to travel to eliminate HIV: the case of Malawi by Professor Sally Blower

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Professor Sally Blower

April 19 @ 12:00 pm - 1:00 pm PDT


Background: Malawi has a severe HIV epidemic: prevalence is 11%. Currently, treatment coverage is 67%; the governments’ goal is to reach UNAIDS’ target of 90% coverage by 2030 and eliminate HIV. The majority of the population live in rural communities at a low population density. We determine how long it will take all (i.e., diagnosed and undiagnosed) HIV-infected individuals in Malawi to travel to access treatment.

Methods: We construct a geographic accessibility map based on travel-time. To perform this analysis, we integrate three maps: a spatial map of the healthcare infrastructure, a density of infection (DoI) map, and a friction-surface map. We generated the DoI map by using geo-referenced HIV-testing data from ~16,000 individuals (15-49 years old) who participated in the 2015 Malawi Demographic and Health Survey, and demographic data from the WorldPop database. We generated the friction-surface map by overlaying a map of road and river networks with spatial data on land cover and topography. The friction-surface map shows the time it takes to travel across one grid of the map. Using the accessibility map, we calculated the functional relationship between the HIV epidemic and travel-time to access treatment.

Results: We find that, nation-wide, 90% of HIV-infected individuals can access treatment by traveling for ~80 minutes or less. However, healthcare in Malawi is decentralized into 28 healthcare districts; we find considerable inequities in access to treatment. In the most urban districts (Blantyre and Lilongwe) the travel-time for 90% of HIV-infected individuals is 35 minutes or less. In one of the most rural districts, Chitipa, travel-time is 160 minutes or less. Notably, we also find considerable differences among districts in the spatial distribution of their HIV epidemics: in the most urbanized districts the DoI is ~1,000 infected individuals/km2, in the most rural district there is only one infected individual/km2.

Conclusions: In order to reach UNAIDS’ target of 90% coverage, healthcare districts will need to address different challenges. Clinics in rural districts will need to employ strategies to minimize travel-times. Clinics in the most urbanized districts, due to their accessibility and the high DoI, may be overburdened in their ability to provide services.


Sally Blower, PhD, is a Professor in the David Geffen School of Medicine at the University of California at Los Angeles. She is a biomathematician and evolutionary biologist whose research focuses on developing models of transmission dynamics. She uses these models as health policy tools: to design epidemic control strategies for a variety of infectious diseases, to understand and predict the emergence of antibiotic and antiviral drug resistance, and to develop vaccination strategies. The main focus of her research is to develop the study of infectious diseases into a predictive science. Recently her work has focused on HIV, Syphilis, Genital Herpes, Smallpox, MRSA, Tuberculosis, Leprosy, Trachoma, and Influenza.

Please RSVP to Stuart Gaffney; also let him know if you are coming from outside Mission Hall and need to be put on the building security list. 


AmfAR Conference room MH-3700

550 16th Street (at 4th Street), 3nd Floor

Mission Bay, SF 94158


April 19
12:00 pm - 1:00 pm
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Estie Hudes, PhD, MPH
Stuart Gaffney


Center for AIDS Prevention Studies
550 16th St, 3rd Floor, Rm 3700
San Francisco, CA 94158 United States
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(415) 476-6288