Beijing has accused Washington of having “suspicious intentions” against China with its pledge to donate millions of coronavirus vaccine doses to countries in need. US President Joe Biden said on Monday that the United States would send 80 million free doses of Covid-19 vaccines overseas, saying the total was more than that pledged by China and Russia. Biden also said the US wanted to “lead the world with our values” amid “a lot of talk about Russia and China influencing the world with vaccines”. Chinese foreign ministry spokesman Zhao Lijian said on Tuesday that Beijing welcomed the commitment but the focus on China was “contemptible”. “If the US is able to live up to their vaccine promises as soon as possible and contribute to the fight against the pandemic in the developing world, China would welcome that,” Zhao said. “The US is always bringing China up when it addresses vaccine issues, such an attitude is contemptible. It makes people suspicious of the true intentions behind the US. “Unlike the US, China is not aiming to lead the world with vaccines. We will not shout empty slogans that are without action,” Zhao said, adding China’s offers came with no political strings attached. How China took an unlikely lead in the global supply of Covid-19 vaccines China has promised to provide 10 million doses under the Covax scheme, backed by the World Health Organization, for lower and middle-income countries. Critics have described China’s offers as “vaccine diplomacy” aimed at winning diplomatic points and future business opportunities. But Beijing says its vaccines are for the “global public good”. Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations, said the US move came as China was battling tight supplies in its race to vaccinate 40 per cent of its population by July and meet overseas obligations. “The golden era of the Chinese vaccine diplomacy could be over soon,” Huang said. “The US vaccine donations could be a real game-changer.” Production in China was expected to improve by the second half of the year, but by that time the US and some other Western countries could have most of their populations vaccinated, freeing up a big surplus for donations, he said. “So despite China’s early lead, the window of opportunity for its vaccine diplomacy is closing,” Huang said. Nicholas Thomas, professor of global health security at City University of Hong Kong, said the US’ donation target was significant because it would make it the world’s largest supplier of vaccines. “This, coupled with the fact that all US pharmaceutical companies have fully shared their phase 3 trial data, should reassert the US position as a leading, trusted supplier. However, this does not mean that the situation is a zero-sum game for China,” Thomas said. “Chinese pharmaceutical companies have established a significant vaccine presence globally, but especially in the developing world. In essence, this move by the United States not only helps to blunt the current wave of the virus but it also gives a measure of choice back to the recipient countries.” Biden said 20 million doses of the doses were expected to be from Pfizer , Moderna and Johnson & Johnson, while the remainder would be by AstraZeneca – once that jab was approved by the US Food and Drug Administration. Pfizer and Moderna jabs both have efficacy rates of over 90 per cent, which are higher than the roughly 78 per cent of the WHO-approved shot by Chinese state firm Sinopharm. The efficacy of CoronaVac , made by Chinese company Sinovac Biotech, ranged from 50.7 to 84 per cent. Wang Yiwei, an international relations professor at Renmin University in Beijing, said he had doubts that the US could realise its offer. “China is not worried about the US aiming to provide a lot more vaccines than China has pledged. We are just worried that the US will not be able to live up to its promise,” Wang said. “It has been understood that some of the vaccines the US will provide have very specific standards in terms of the logistics and storage conditions.” Pfizer shots must be kept at minus 70 degrees Celsius (minus 94 Fahrenheit) and thawed and diluted before injection. Each inoculation centre is equipped with two pharmaceutical fridges to store the vials at temperatures of between 2 and 8 degrees for no more than five days. The prepared solutions must be used within six hours and cannot be stored at above 30 degrees. AstraZeneca vaccines have similar storage requirements as the Sinopharm and Sinovac shots – up to six months in a refrigerator at 2-8 degrees Celsius. The Johnson & Johnson and Moderna vaccines can be stored at similar temperatures for up to 30 days, but the Moderna vaccine requires colder long-term storage at around -20 degrees Celsius. But Thomas, from CityU, said he did not see storage conditions as a significant challenge to distribution of the US vaccines. “The vaccines donated by the United States [with the exception of Pfizer] will be able to be used in all countries where the Chinese vaccines are currently being distributed,” he said. “The Pfizer vaccine will have a more limited geographical utility but as we do not yet know what doses are going where it is too early to say that this would cause any significant issues for the distribution.” In March, Washington also announced that, with three of its closest Indo-Pacific partners in Quad framework, it was committing to supplying up to a billion coronavirus vaccine doses across Asia by the end of 2022.