Winnie Yu is a Hong Kong nurse and activist. She is the founder and chairwoman of the Hospital Authority Employees Alliance (HAEA), a labour union representing Hospital Authority staff. She played an instrumental role in the labour strike in February 2020 to demand full border closure in response to the COVID-19 outbreak in Hong Kong.

In the 2019 anti-extradition protests, Yu became active in social activism, volunteering as a paramedic. The Hospital Authority Employees Alliance (HAEA) was founded in the call for forming labour unions to launch a city-wide strike to pressure the government, in which Yu became the chairwoman. HAEA fought for stronger border control during the beginning of the covid-19 pandemic, demanding that the government prevent all non-Hong Kong residents from entering the city via the mainland. Yu then helped to organize a strike of more than 2,500 people to protest for stronger closures.

Yu participated in the 2020 Hong Kong pro-democracy primaries, winning against the incumbent. In January 2021, Yu was among 53 members of the pro-democratic camp who were arrested under the national security law, specifically its provision regarding alleged subversion. Yu was released on bail on 7 January.

On 28 February, Yu was formally charged, along with 46 others, for subversion. After she was charged, she was suspended from her duties by the Hong Kong Hospital Authority. On 28 July, she was released on bail, after her bail application being granted by High Court judge. 

According to a written judgment that was released by the judiciary on 14 September, the judge granted her bail, observing in her written explanation that there was no evidence that Yu ever had an international connection. On 8 March 2022, one day after Yu being arrested again, her bail was revoked by a magistrate; as the application of defense for lifting of reporting restrictions was turned down, the nature of the violation of bail conditions was not immediately clear. [1]