About 373 million people in 45 cities across China have come under some form of lockdown due to a surge in coronavirus cases amid the spread of the highly contagious Omicron variant, according to estimates by a Nomura Holdings Inc. unit. The figure amounts to 26.4 percent of the total population, as the government in Beijing continues to pursue a radical zero-COVID policy, fueling concerns that stringent measures could negatively affect the world’s second-largest economy and the global supply chain. In China’s financial and commercial hub of Shanghai, many parts of which have been locked down …