China raced to vaccinate its most vulnerable people on Thursday in anticipation of waves of Covid-19 infections, with some analysts expecting the death toll to soar after a loosening of strict controls that kept the pandemic at bay for three years.

The push comes as the World Health Organisation also raised concerns that China’s 1.4 billion population was not adequately vaccinated, and the United States offered to help China deal with a surge in infections. Beijing last Wednesday began dismantling its tough ‘zero-Covid’ controls, dropping testing requirements and easing quarantine rules that had caused mental anxiety for millions and battered the world’s second largest economy.