The suggestion that there are some 1,500 asymptomatic Covid-19 patients moving around undetected may not sound particularly alarming for a population of 7 million with some 4,000 infections. But the figure may multiply exponentially if the hidden transmission chains go unchecked over time, as evidenced in the recent sharp rise in cases of unknown origin. Even though the surge appears to have somewhat eased over the past week, the spiralling death tolls, many among the elderly with chronic illnesses, are a sad reminder that the latest wave of the outbreak is far from over. Wider measures are urgently needed to bring the situation under control. Having been criticised for its low testing capacity, the government will offer a free test for everyone in two weeks. A special squad from across the border will work with three mainland-linked laboratories to cope with the estimated demand of 5 million people. Chief Executive Carrie Lam Cheng Yuet-ngor believes it will help identify the so-called silent carriers. Whether a voluntary universal test is the answer to a raging epidemic remains to be seen. But if the test results from targeted groups are any guide, there is one positive case in every 2,500 samples. The compound effect is clearly not something our overstretched health care system can afford. The premature announcement of the initiative without essential details is testimony to Lam’s eagerness but, despite repeated assurances of personal data protection, resistance remains strong among some locals. Universal Covid-19 testing for Hong Kong tougher than it sounds: health experts This is to be expected in the wake of growing anti-mainland sentiment fuelled by a series of political controversies. Some see it as Lam helping Beijing to score points in fighting the epidemic. Meanwhile, medical experts remain divided over the effectiveness of the approach, with some saying it will only work if the tests can be done within two weeks under a lockdown to help stamp out transmission. There are also questions as to whether people have the know-how to provide samples correctly for accurate testing. The government should think carefully about logistics and promote greater participation to ensure its success.