If society is serious about slowing the spread of HIV, there’s one simple thing it can do, a new study claims.

Slashing the number of men who go to jail would in turn greatly slow the spread of HIV, indicating that mass incarceration can actually encourage the spread of disease, according to a UPI report.

In addition, incarcerating men and then returning them to society also increases the number of sexual partners they have, which may be the biggest factor in the spread of disease. To make this finding, researchers ran a simulation to see how many partners individuals would have, and then ran simulations with incarceration involved. They found that incarceration increased sexual partners for both genders. The longer the sentence was, the worse it was.

“The model shows that simply removing men and returning them to the community frequently can increase the number of sexual partners that both men and women have in the community,” Dr. Andrea Knittel, a researchers at the University of California San Francisco who was involved with the study, said in a statement. “It supports the assertion that mass incarceration has complicated and far-reaching unintended consequences, and may have significant public health implications.”

She added: “Our model showed that high levels of incarceration likely play a role in community-level sexual behavior, and are likely detrimental in terms of sexual risk for HIV and other STDs. The results suggest that reducing incarceration and creating a more open criminal justice system that supports the maintenance of inmates’ relationships to reduce instability of partnerships for men who are incarcerated may have important sexual health and public health implications.”

The findings were published in the journal of Social Science and Medicine.