Ye Haiyan, one of China’s most prominent sex worker-rights activists, won’t be attending the major international conference on AIDS in Melbourne, Australia next week. Known by her online nickname “Hooligan Sparrow,” Chinese authorities have told Ye her passport has been “lost” after she attempted to apply for a visa, making it impossible to travel.

Ye’s efforts have invoked the authorities’ wrath before. In 2006, she began providing information and counseling to sex workers, eventually establishing organizations in two provinces to provide them with health and legal services. And she has been a forceful advocate for sex workers’ legal rights. For these efforts she has endured house arrest, harassment by local authorities, and police raids of her offices and home. In May 2013, the police detained Ye for several days after unidentified assailants assaulted her at her home in Guangxi province because she exposed abusive conditions in local brothels.

Why wouldn’t the Chinese government want all the help it can get in tackling HIV? The track record is clear in country after country: where sex workers are criminalized, where their human rights are violated and their access to HIV prevention and treatment are denied, HIV epidemics get worse. Where sex work is legal, and sex workers can organize and promote HIV programs and services, the epidemic wanes. The International AIDS Conference is the premier global event at which policymakers, academics, activists, and others come together to swap solutions and debate strategies. Sex workers had planned to have a session in advance of the formal conference, and Ye had intended to give a presentation on “Sex workers as human rights defenders.”

The conference declaration says, “An end to AIDS is only possible if we overcome the barriers of criminalization, stigma and discrimination that remain key drivers of the epidemic.” Blocking Ye’s participation shows that the Chinese government is moving in the wrong direction on key public health concerns and respecting the right to peaceful expression.

Ye now joins the ranks of other well-known individuals, including artist Ai Weiwei, to be prevented from leaving China. But in doing so the authorities only compound their own problems: not only do they embarrass themselves before a global audience by employing absurd and thuggish tactics to prevent Ye from participating at the Melbourne gathering, they also deny people in China access to the latest thinking and most effective strategies in combatting a serious public health challenge. Beijing can begin to minimize insult and injury to Ye and all those living with HIV-AIDS by allowing her to travel freely.