President Xi Jinping has called on officials to make Covid-19 control their top priority and to swiftly contain an outbreak that has now spread to most parts of China. Xi also said China would stick to a strategy to “prevent Covid-19 being introduced from overseas and causing local transmission” – or zero-Covid – in a meeting of the Politburo, the Communist Party’s top decision-making body, on Thursday. The president called for efforts to overcome wariness and complacency, as the country enters a third year of tough coronavirus restrictions while much of the world has opened up. “In places with a serious epidemic situation, the main leaders of the party and the government should take epidemic control work as their first priority,” Xi told the meeting, according to state news agency Xinhua. “Supervision and accountability will be strengthened. Those whose dereliction of duty leads to the epidemic getting out of control will be immediately investigated and severely punished.” It comes as China is battling its worst outbreak of locally transmitted cases since the start of the pandemic, with millions of people in lockdown as the highly transmissible Omicron variant spreads. Daily case numbers have been steadily climbing since the start of March and topped 5,000 local infections on Tuesday – the highest number since the initial Wuhan outbreak. The number has dipped in the past two days, with 2,432 local cases – with and without symptoms – reported on Thursday, down from 3,054 a day earlier, but experts say it is too early to tell if the situation is easing. Cases have been reported in all parts of mainland China except for the Xinjiang, Tibet and Ningxia Hui regions. WHO says global rise in Covid-19 cases ‘tip of the iceberg’ Xi said the widespread outbreak would require strict implementation of prevention and control measures to contain it. He said the zero-Covid policy had ensured China’s “leading position of economic development and epidemic control” and reflected the nation’s “solid strength and strong power” to handle outbreaks. The remarks come ahead of a twice-a-decade party congress in autumn, at which Xi is expected to secure an unprecedented third term as leader. He urged officials to understand the complex and difficult nature of the situation and to get it firmly under control, saying “persistence is victory”. The president also vowed to take more effective measures but to minimise their impact on the economy and people’s lives. Earlier this month, Premier Li Keqiang acknowledged that Covid-19 had dealt serious blows to China’s service industry, and set the lowest economic growth target for 31 years. Xi on Thursday also called for improved efforts at the country’s borders to prevent cases from being brought in, and to push forward the booster vaccination campaign. Although case numbers have fallen in the past two days, Hong Kong respiratory expert Dr Leung Chi-chiu said it would take “a little bit longer” to tell if the outbreak had reached its peak. He said rounds of mass testing and lockdowns would ensure that the numbers start to go down. “It’s a case of whether all the transmission chains can be fully eliminated before the lockdown is lifted,” Leung said. “I believe it will happen in phases. There will still be cases at a localised scale before transmission is completely eliminated, but the question is … how long the economy and people … can tolerate lockdowns before all transmission is eliminated,” he said. “If it fails, cases will rebound when normal economic activities resume – like what you’ve seen in other parts of the world.” Leung expected local transmission could be curbed within a reasonable time, but said the northeastern province of Jilin – the worst hit in the latest outbreak – would be the main problem. “We’ll need to see how the cases go in the coming weeks,” he said.