An extra year of schooling can cut the risk of HIV infection by a third, a new study shows.
The study, its authors say, is evidence that education is cost-effective HIV prevention, not even counting all the other benefits.
Despite unprecedented global public health efforts, HIV infects more than two million people each year.
Botswana has among the world’s highest HIV infection rates. Nearly a quarter of the population is infected.
Many experts believe more educated people are less likely to contract the virus, but it has been hard to prove.
In 1996, Botswana made a change in its education system that offered a natural experiment. The government moved grade 10 from senior to junior secondary school, which previously ended at grade 9.
Students need to graduate from junior secondary school to go on to vocational training. And there are many more of these schools than senior secondary schools.
“It made grade 10 much more accessible to people and increased the benefits for completing” the additional grade, said study co-author Jacob Bor, a health economist at Boston University School of Public Health.
The researchers wanted to see what impact that extra year of schooling had years later, when the students were adults. They compared national health surveys taken in 2004 and 2008.
“The effects were large,” Bor said. “We were surprised how large they were.”
Writing in the journal The Lancet Global Health, the study found the risk of infection overall fell more than eight percentage points, from 25.5 percent to 17.4 percent. The effects were even larger for women: 11.6 percentage points. A battery of statistical tests “couldn’t make them go away,” Bor added.
“I think that this study really provides evidence that we should consider formal schooling, particularly secondary schooling, as part of HIV prevention,” he said.
And it was cost-effective. Each HIV infection prevented cost more than male circumcision but roughly the same as giving anti-HIV drugs to uninfected people at high risk of contracting the virus.
Bor noted that the researchers only looked at the cost of preventing HIV infection. “If we were to account for all the other benefits of schooling, then the cost-effectiveness would, I think, make it a slam-dunk,” he added.
In an accompanying commentary, New York University health economist Karen Grepin said the study provides strong and compelling evidence that education can lower HIV risk. “The primary reason (for education) isn’t for the health effects," she said, "but the health effects themselves can be large as well."
It’s not clear exactly how education lowers HIV risk. Botswana did not have a national HIV education curriculum in 1996.
“That’s, I think, one of the most fascinating pieces about this,” Bor said. “What we’re seeing is not the effect of HIV-specific education, but education more generally. Which then raises the question, what are people getting?”
More education improves job prospects, which might be especially important for women. In sub-Saharan Africa, Bor said, women frequently “find themselves in economically dependent sexual relationships where they don’t necessarily have enough power in those relationships to insist on condom use or avoid risk” in other ways.
Also, the additional schooling may be improving cognitive skills that help people make better decisions.
But in addition to learning skills, students at that age are “forming a sense of who they are and what their future is going to be,” he notes, such as, “whether my future has a career in it, or whether my future is going to be about finding a husband.”
At this point they don’t know the answer, but Bor says upcoming research will address those questions.