BEIJING -- A teacher training program focusing on teenage sex education concluded in Beijing on Friday.

About 50 teachers in 35 schools in Beijing's southern district of Fengtai joined the week-long program, which was organized by the AIDS Prevention Education Project for Chinese Youth (APEPCY), a non-profit organization.

"Sex education is the key to AIDS prevention, as more and more young students are being infected due to lack of sexual knowledge," said Zhang Yinjun, the founder of APEPCY.

According to a report released by Chinese Center for Disease Control and Prevention, 2,321 new AIDS cases of students aged 15 to 24 were found from January to September 2016, 4.1 times more than the same period in 2010.

Over 10 experts in AIDS prevention and control as well as in sex education carried out training courses, including on sexual development, sex education in foreign countries and AIDS prevention, which helped teachers design curriculums.

"There is a great demand for sex education as more sexual assault appeared among teenagers," said Xing Haiyan, secretary general of APEPCY. "It is necessary for students to receive sexual health education at an early age."

APEPCY started training teachers on sex education in July 2017. The program will last for four years.