Evaluating social protection mitigation effects on HIV/AIDS and Tuberculosis through a mathematical modelling study

Abstract

The global economic downturn due to the COVID-19 pandemic, war in Ukraine, and worldwide inflation surge may have a profound impact on poverty-related infectious diseases, especially in low-and middle-income countries (LMICs). In this work, we developed mathematical models for HIV/AIDS and Tuberculosis (TB) in Brazil, one of the largest and most unequal LMICs, incorporating poverty rates and temporal dynamics to evaluate and forecast the impact of the increase in poverty due to the economic crisis, and estimate the mitigation effects of alternative poverty-reduction policies on the incidence and mortality from AIDS and TB up to 2030. Three main intervention scenarios were simulated-an economic crisis followed by the implementation of social protection policies with none, moderate, or strong coverage-evaluating the incidence and mortality from AIDS and TB. Without social protection policies to mitigate the impact of the economic crisis, the burden of HIV/AIDS and TB would be significantly larger over the next decade, being responsible in 2030 for an incidence 13% (95% CI 4-31%) and mortality 21% (95% CI 12-34%) higher for HIV/AIDS, and an incidence 16% (95% CI 10-25%) and mortality 22% (95% CI 15-31%) higher for TB, if compared with a scenario of moderate social protection. These differences would be significantly larger if compared with a scenario of strong social protection, resulting in more than 230,000 cases and 34,000 deaths from AIDS and TB averted over the next decade in Brazil. Using a comprehensive approach, that integrated economic forecasting with mathematical and epidemiological models, we were able to show the importance of implementing robust social protection policies to avert a significant increase in incidence and mortality from AIDS and TB during the current global economic downturn.

Figure 1

Structure of the compartmental models for HIV/AIDS and Tuberculosis. (a) HIV/AIDS transmission model: (S) those susceptible to HIV infection via sexual contact, (I) HIV-positive individuals who are infectious, (A) individuals with full-blown AIDS, (T) individuals being treated and who therefore have an undetectable viral load, (R) individuals who are not yet sexually active or have changed their sexual habits, so they are no longer part of the susceptible population. (b) Tuberculosis transmission model: (S) susceptible, (P) primary infection, (L) latent infection, (I) active tuberculosis disease.

Figure 2

Time series of the poverty rates in Brazil between 2003 and 2019, and potential scenarios between 2020 and 2030. Poverty Rates are expressed as proportion (from 0 to 1).

Figure 3

Incidence and mortality rates due to AIDS and Tuberculosis from 2003 to 2030 according to different social protection scenarios. (a) AIDS incidence under different scenarios of social protection between 2003 and 2030, (b) AIDS-related mortality under different scenarios of social protection between 2003 and 2030, (c) Tuberculosis incidence under different scenarios of social protection between 2003 and 2030, and (d) Tuberculosis mortality under different scenarios of social protection between 2003 and 2030. Shaded bands represent 95% of simulated predictions by social protection level.