High levels of vaccination will help contain the spread of Covid-19, but are no guarantee of victory. The emergence of variants that have the potential to overcome the immunity brought about by jabs means there can be no let-up in public health measures. Tough action was taken by Hong Kong through the barring of travellers from the directly affected countries of Brazil, Britain, Ireland and South Africa. With mutations in India, Pakistan and the Philippines and the number of cases there rising amid new waves, some experts are calling for a fresh clampdown. Hong Kong has largely brought the transmission of local infections under control, although there are concerns about silent carriers. Most daily cases are imported, and invariably India, Pakistan, the Philippines and Indonesia feature. Outside China, only permanent residents or those with work and study visas are allowed entry; large numbers of people from those countries live in the city. There is particular anxiety about the Philippines, a main source of domestic helpers, which is struggling to cope with a fresh surge in infections and where a mutation of the British variant is prevalent. Daily infections in the Philippines rose to a record last week. One in five Covid-19 tests comes back positive. The number of cases in India and Pakistan are also sharply rising with new waves under way. There are understandable fears in Hong Kong of serious outbreaks unless imported cases are stopped. The city is already relaxing measures, organising special flights to bring residents back from Britain later this month now that infection numbers there are down. Non-residents from Australia, New Zealand and Singapore, with good records, are also being allowed to visit from today with the quarantine period reduced from 21 to 14 days. But the surges in the Philippines, India and Pakistan have to be closely monitored. Suspension of flights or proof of vaccination may be necessary. Hong Kong hints at new arrangement to bring home residents stranded in Britain Hong Kong’s vaccination programme has to be accelerated. But the threat of coronavirus variants and the risks they pose mean tough public health measures have to continue. We have to be alert and ready to resolutely respond to outbreaks locally as well as overseas.