New research suggests that people who have more secondary schooling are less likely to contract HIV, The Business Standard reported.

Researchers at Harvard University found that  for each additional year of secondary school (grades 8 to 12) students lowered their risk of HIV infection by 8 percentage points about a decade later, from 25  to about 17 percent  infected.

"These findings confirm what has been fiercely debated for more than two decades -- that secondary schooling is an important structural determinant of HIV infection and that this relation is causal," Jan-Walter De Neve, first author of the study and a doctoral student in the Department of Global Health and Population, said in a statement.

For the study, researchers collected and analyzed data from about 7,000 people, Medical News Today reported. They also compared cohorts of students who entered secondary school in or after 1996 with those in earlier cohorts to estimate the impact of additional secondary education on the risk of HIV infection.

They found that additional years of secondary school were linked with significantly lower risk of HIV, particularly for women, whose HIV risk dropped by 12 percentage points with each added year of secondary school. No effect was found for people with less than nine years of schooling.

Researchers also looked at the cost-effectiveness of secondary schooling and found that while additional schooling is more expensive than some HIV prevention interventions it's similar to the upper range of estimates for pre-exposure prophylaxis (taking a daily pill to prevent HIV).

HIV continues to be a major global health challenge, with an estimated 2.1 million people becoming newly infected each year.

The findings are detailed in the journal Lancet Global Health.