The rush to inoculate billions of people against Covid-19 around the world has always been a challenge. With the vaccines so new and confidence so fragile, any mishaps may just undermine the global drive. The finding of a possible link between AstraZeneca jabs and blood clots is a case in point. Pressure is growing on authorities across the globe to determine what to do with the vaccine in question. The Hong Kong government yesterday announced that the vaccine would not arrive this year as planned, saying the two other types currently in use would be adequate for the time being. Amid a resurgence in infections in many regions, the acknowledgement by the European Medicines Agency of rare blood clots as a possible side effect has inevitably dealt a blow to places solely reliant on AstraZeneca jabs to stamp the pandemic. Even though the authority stressed the benefits still outweighed the risks, it prompted swift adjustments in some countries. For instance, those aged 30 and under in Britain are to be given another vaccine. In South Korea, AstraZeneca jabs were being resumed following a brief suspension, pending further deliberations. The jab developed by the British-Swedish pharmaceutical giant and Oxford University was due to arrive by the end of the second quarter of this year. Officials planned to provide no fewer than three types of vaccines for people to choose from, with Sinovac and BioNTech already rolled out. There were also talks of a fourth one, although no specifics have been revealed. Hong Kong experts push to replace AstraZeneca’s jabs with J&J’s Health chief Professor Sophia Chan Siu-chee yesterday revealed there would be no need for AstraZeneca vaccines this year, saying the two other types, totalling 15 million doses, would be enough. But she conceded that the halt had also taken into account concerns over blood clotting. Suppliers had been told to prepare for second-generation vaccines that offer stronger protection against mutated strains, she added. The safety and efficacy of vaccines have always been an issue of concern. In Britain, there were at least 79 cases of blood clotting, 19 of which resulted in death. The mishaps are just a fraction of the 20 million doses administered so far. But they give sceptics more reasons to think twice. Many Hongkongers are still adopting a wait-and-see attitude. Even though medical experts say the fatalities and serious side effects reported in the city so far have no direct link to the jab, scepticism abounds. That is why the uptake is barely above 7 per cent of the eligible population. Hong Kong is fortunate to have more than one type of vaccine on offer. But the low uptake, as Chief Executive Carrie Lam Cheng Yuet-ngor said, was puzzling. The government’s response is in line with the suggestions by some medical experts, which hopefully may enhance public confidence in inoculations.