Unlike neighbouring Shenzhen, which has just implemented a lockdown for mass Covid-19 testing overnight, Hong Kong still faces the same prospect with drawn-out trepidation. First it was imminent and now it has been delayed to an unspecified date, if it goes ahead at all. This is to make way for other priorities such as timely treatment of the seriously ill and vaccination of the elderly. The clearer focus on priorities is welcome. But the remaining uncertainty about mass testing does nothing for confidence, especially for operators and employees of businesses temporarily shut down under social-distancing measures. Meanwhile, the Shenzhen lockdown offers a view across the border of what effective mass testing really means. Ironically, the outbreak there, which accounts for most cases in Guangdong, is linked to the devastating fifth wave of the coronavirus in Hong Kong. The technology hub has already locked down border areas near Hong Kong while battling a surge in infections with the Omicron variant of the virus since late last month. Shenzhen can hope to emerge from the lockdown after three rounds of citywide Covid-19 tests this week. Meanwhile, to help make the testing effective in identifying infection chains, residents are urged to work from home and step out only to buy necessities from supermarkets, pharmacies, medical institutions and takeaways, which are exempted from closure. The first lesson to be learned from Shenzhen is that a lockdown and mass testing are more likely to be effective at the beginning of an outbreak. However, as Chief Executive Carrie Lam Cheng Yuet-ngor rightly said, even if Hong Kong were willing to launch mass testing and a lockdown in the next few days it did not currently have the necessary manpower. In any case, with 300,000 Covid patients and close contacts quarantining at home, it is not the right time. But if and when the time comes for Hong Kong to follow suit it will still pay to keep Shenzhen’s experience in mind. Another lesson is to be prepared to introduce it in a quick, decisive and timely fashion – not through bits and pieces of information that prompt irrational panic buying and anxiety. It was also business as usual on Monday on the Shenzhen Stock Exchange, a reminder that Hong Kong also must be well prepared if massive tests are to go ahead. Hong Kong ‘should learn from Shenzhen’s organised’ Covid-19 lockdown’ China’s strict controls, with swift lockdowns, travel curbs and mass testing, are unlikely to be eased any time soon. But Premier Li Keqiang implied in his recent annual report to the National People’s Congress they will be fine-tuned to minimise economic disruption. The mainland’s worst outbreak for two years, driven by the highly transmissible Omicron variant, is putting that approach to the test.