【明報專訊】With the fourth wave of the COVID-19 pandemic striking Hong Kong, the government has tightened its anti-pandemic measures, requiring that designated premises put up a QR code designed for the "LeaveHomeSafe" app (the app). Experience and actual practice teach us that pandemic control measures should not depend on voluntary co-operation merely. Mandatory arrangements that are reasonable and appropriate can help the public pick up some anti-pandemic habits as soon as possible, one example being having the temperature taken before entering different premises. The authorities should take vigorous action by ordering that citizens scan the QR code with the app before entering high-risk premises. The public should also set aside political divisions and co-operate in fighting the pandemic.