China imposed new restrictions on travel in a bid to slow a delta-driven outbreak that’s grown to more than 500 cases scattered across half the country, as the government stuck to an aggressive containment playbook rather than rely on its high vaccination rate.

Public transport and taxi services were curtailed in 144 of the worst-hit areas nationwide, while officials curbed train service and subway usage in Beijing, where three new cases were reported Wednesday. Hong Kong re-imposed quarantine on travelers from the mainland, though an exception remained for the southern Guangdong province which neighbors the financial city.

Officials reported 94 new local infections on Thursday, including 32 that were asymptomatic, adding to the country’s broadest Covid-19 threat since the pathogen first emerged in Wuhan in late 2019. Though 61% of the population has been vaccinated, one of the highest rates among the world’s biggest countries, China has stuck to its tried-and-true approach of mass testing and targeted lockdowns that’s crushed over 30 previous flareups.