Rates of HIV infection in China have climbed more than 400% among gay men in the past five years and grew more than 350% among men over the age of 60 in the past six years, the nation’s Center for Disease Control recently reported.

Across the country, more than 654,000 people (link in Chinese) are living with HIV, the infection that causes AIDS, according to the center. Of the new HIV cases reported so far this year, 94.2% came from sexual interactions, with male same-sex and male prostitution of particular concern.

New HIV cases among gay men increased 420% from 2010 to 32,617 cases in 2015 (link in Chinese), the center said. Between January and September of this year, the number of new HIV cases among men over 60 jumped 360% from the first nine months of 2010, to 13,000 cases (link in Chinese). The center said this was due to due to “poor sexual behavior,” with the implication being these men were interacting with prostitutes.

New cases also rose sharply among students aged 15 to 24 from the first nine months of 2010 to the same time this year, jumping 410% to 2,321.

One online commenter who said she was a medical school graduate bemoaned (link in Chinese) the lack of sex education among students, saying she had encountered many who were unaware of AIDS when they became infected. They were “curious about sex,” she wrote, but not taught about the disease. Students at one university in Sichuan province are being offered HIV testing kits through vending machines, and can check the results anonymously online.

Various measures have been taken in China to combat the disease. For those already infected, a domestically developed drug called Albuvirtide—nearing approval—promises to reduce the effects and lower the risk of contamination to others. It will replace standard triple drug therapies with a single injection once a week.