Hong Kong has had its first confirmed cases of the Wuhan coronavirus, prompting the government to cancel major Lunar New Year events and tighten health declaration requirements for travellers. This may have been inevitable since the infection had already spread to other parts of Asia. But it drives home the public health threat to the city of the most serious communicable disease outbreak in China since Sars in 2002-2003. Unprecedented measures imposed by mainland authorities underline it. A total lockdown of the central Chinese city of Wuhan, to prevent the population of about 11 million from leaving freely and hopefully contain the chain of contagion, is unlike anything seen in the People’s Republic for decades. It has since been imposed on other cities in Hubei province. Quarantine is the most effective response, even on such a massive scale. There is no cure for this new virus, nor a drug for effective treatment. It will take time to develop them. And we have entered a period of increased risk of infection, with millions on the move for the Lunar New Year holiday. The intervention of President Xi Jinping to order officials to give top priority to preventing and controlling spread of the disease, has proved decisive. If local authorities had acted with a greater sense of urgency two weeks ago the quarantine measures may not have been so drastic. The Hong Kong government needs to apply the lessons of the Wuhan crisis as well as the painful Sars experience. The main one is not to underestimate the coronavirus outbreak or hold back from decisive counter measures because of misguided fears they might cause panic. The way to avoid panic is for the government to be seen taking decisive precautions. In that respect the cancellation of events and tighter health declaration requirements for travellers are welcome, although medical experts are rightly critical of failure to apply the latter measure sooner for high-speed rail passengers. Widening the criteria for doctors to report suspected cases and putting mass quarantine facilities in place are sensible steps. But there is still room for officials to step up with a greater sense of urgency, especially on travel precautions. It should impose a travel ban on Wuhan and campaign actively to discourage unnecessary journeys. Another lesson learned from the Sars outbreak is the importance of educating people on the need for cleanliness and diligent handwashing wherever they may be.