Length of secondary schooling and risk of HIV infection in Botswana: evidence from a natural experiment

De Neve, J-W; Fink, G; Subramanian, SV; Moyo, S; Bor, J The Lancet Global Health, 2015; www.thelancet.com/journals/langlo/article/PIIS2214-109X(15)00087-X/fullte...

In 1996, Botswana shifted Grade 10 from senior- to junior-secondary school, leading to a large increase in educational attainment for girls in that cohort. Exploiting this policy change as a natural experiment, this study identifies protective effects on HIV infection, with the largest effects for women. From these findings, the authors aim to identify the causal effect of length of schooling on new HIV infection.

HIV continues to be a major global health challenge with an estimated 2.1 million new infections each year. Formal education, particularly of girls, is seen as a social vaccine to reduce the spread of HIV. But previous studies – both cross-sectional and longitudinal – have reported conflicting evidence for the association between education and HIV risk. No randomised trial has identified a causal effect for education on HIV incidence. This study presents the first causal evidence (from a natural experiment or trial) that formal schooling reduces HIV infection risk. The results are consistent with evidence from prior association studies and trials with HIV risk factors as endpoints.

The analysis concludes that secondary schooling is highly cost effective as an HIV prevention intervention. Of relevance to all involved in STRIVE, this work supports further investment in structural interventions.

Findings

Additional years of secondary schooling had a large protective effect against HIV risk in Botswana, particularly for women. Increasing progression through secondary school could be a cost-effective HIV prevention measure in HIV-endemic settings, in addition to yielding other societal benefits.

  • The crude association between HIV infection risk and amount of schooling peaked for people completing eight to nine years of education and declined sharply thereafter.
  • Each additional year of schooling after nine years was associated with a 3.6% lower risk of HIV infection. By contrast, there was no association between schooling and HIV risk in lower grades.
  • The fraction of students completing at least 7, 8, or 9 years of schooling rose gradually and continuously across birth cohorts. 
  • Women who were exposed to the reform were 7% less likely to be HIV positive than those not exposed to the reform; men were 5% less likely to be HIV positive. 
  • Each additional year of secondary schooling caused by the policy change led to an absolute reduction in the cumulative risk of HIV infection of 8.1%, relative to a baseline prevalence of 25.5% in the pre-reform 1980 birth cohort. 
  • Effects were particularly large in women (11.6% points). 
  • Since individuals who stayed in school for an additional year had an 8.1% point lower risk of HIV infection, the cost per HIV infection averted was $27,753.

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