Increasing secondary education protects against HIV infection

Longer secondary schooling substantially reduces the risk of contracting HIV, particularly for girls, according to new research from Botswana published in The Lancet Global Health journal. The researchers estimate that pupils who stayed in school for an extra year of secondary school had an 8 percentage point lower risk of HIV infection about a decade later, from about 25% to about 17% infected.

The study, which also shows expanding secondary schooling to be a very cost effective HIV prevention measure, used a recent school policy reform as a 'natural experiment' to determine the impact of increased years of secondary schooling on risk of HIV infection.

Implemented in 1996, the reform led to an average increase of 0.8 years of schooling among teenagers, by providing free grade 10 education as part of junior - rather than senior - secondary school. This policy presented a unique opportunity to estimate the causal effect of length of schooling on risk of HIV infection by comparing birth cohorts exposed to the reform versus those unexposed, using data from national HIV surveys collected in 2004 and 2008.

Although education is known to be closely associated with health, whether or not formal education actually protects against HIV infection has been hotly debated for over two decades. Research so far has produced conflicting results.

Jacob Bor, senior author and Assistant Professor of Global Health at Boston University School of Public Health, Boston, USA explains, "It is difficult to isolate the effect of education on HIV risk from the complex web of co-factors such as personal motivation, psychological traits, socioeconomic status, and family background. In the absence of large-scale trial data, natural experiments can provide robust evidence to guide policy."[1]

Using data from two nationally representative household surveys, the Botswana AIDS Impact Surveys (2004 and 2008), the researchers used statistical techniques commonly used in economics and political science to analyse natural experiments. Botswana has one of the highest rates of HIV in the world, with around 22% of adults aged 15-49 years infected in 2013 [2]. The authors investigated the causal effect of an additional year of schooling on HIV status in 7018 men and women at least 18 years old at the time of the surveys. Individuals born in or after 1981 (who would have started junior secondary school in 1996 or later) were classified as exposed to the reform.

The researchers estimate that individuals who gained an extra year of secondary schooling due to the policy were 8 percentage points less likely to test positive for HIV about a decade later, when most of those exposed to the policy were in their mid 20s. The effects were particularly strong among women, with each additional year of secondary schooling reducing infection risk by 12 percentage points.

According to co-author Jan-Walter de Neve, a doctoral student at Harvard T.H. Chan School of Public Health, Boston, USA, ."[1]