US President Joe Biden said his administration would order 100 million more doses each of the Pfizer-BioNTech and Moderna coronavirus vaccines, and at least temporarily speed up shipments to about 10 million doses a week to states. The purchases would increase total US orders for the two approved vaccines by 50 per cent to about 600 million shots, a senior administration official said. That supply was expected to be available by the end of the summer and would be enough for 300 million people. Delivering a minimum of 10 million doses to states would represent about a 16 per cent increase from the current weekly pace, although it may last only three weeks. The government also plans to give states three weeks' warning before shipments, up from one week now. “This is going to allow millions more Americans to get vaccinated sooner than previously anticipated. We’ve got a long way to go, though,” Mr Biden said at the White House on Tuesday, flanked by his Covid-19 co-ordinator, Jeff Zients. Mr Biden cautioned that the vaccination effort was an extremely difficult logistical effort. “A lot of things can go wrong along the way,” he said. Mr Biden has <a href="https://www.thenationalnews.com/world/the-americas/biden-recruits-federal-muscle-for-vaccine-blitz-1.1146836">pledged to administer 100 million shots in his first 100 days</a> in office, also though it was not immediately clear if the measures announced on Tuesday would help him to more easily meet that goal. He said “the vaccine programme is in worse shape than we anticipated or expected". But under the Trump administration, the pace of shots was already accelerating to one million a day. “I want to be clear — 100 million shots in 100 days is not the end point, it’s just the start,” Mr Biden said. The effort is also constrained by limits on the number of sites and medical professionals who can give shots. The senior administration official earlier on Tuesday said the government was working with states to relieve the bottleneck, including by delivering more doses through retail pharmacies. The White House did not immediately respond to questions about the cost of the new order of doses or where the funding would come from. Mr Biden has made curbing the pandemic his top priority, while warning that it will drag on for months even with more aggressive action by the government. He has pleaded with Congress to pass <a href="https://www.thenationalnews.com/world/the-americas/biden-reveals-1-9-trillion-stimulus-package-to-address-covid-crisis-1.1146452">his proposed $1.9 trillion pandemic relief bill</a>, which would include billions of dollars to accelerate vaccinations. Biden administration officials briefed state governors on the vaccination effort on Tuesday. Mr Biden said on Monday that he thought the US could reach 1.5 million vaccinations a day and that any person who wanted a shot might be able to have one by spring. His aides have tempered expectations after that remark, returning to previous projections that most US adults will not be vaccinated until later in the year. The US is administering about 1.3 million doses a day now. That includes Monday, when only 1.1 million shots were recorded. The increase in weekly shipments appears to be largely from Moderna. Government data shows 10.15 million doses that will be made available to states, territories and federal entities for later shipment. The transition between administrations created confusion about how many shots, if any, the federal government had received, but not yet allocated or shipped to states. Shortly before he left office, former president Donald Trump’s administration announced it would release second doses of the Pfizer-BioNtech and Moderna shots that had been withheld. States later complained that they saw no increase in shipments. The senior administration official said the federal government did not have a significant inventory of shots on hand, beyond what was described as a small reserve for emergencies. The two vaccines approved so far from Pfizer-BioNTech and Moderna each require two doses. Approval of a third vaccine would speed up rates. Johnson & Johnson is expected to soon report results of clinical trials of its coronavirus vaccine, which requires only one shot, and could receive Food and Drug Administration approval soon afterward. But the official said the Biden administration was not counting on any more authorised vaccines before the summer. The US recorded 166,000 new coronavirus cases on Monday, down from <a href="https://www.thenationalnews.com/world/the-americas/us-sets-more-covid-19-records-a-year-after-its-first-case-1.1151416">record highs earlier this month</a> but still well above figures seen throughout the autumn.' Another 1,757 people died in the US, pushing the country’s death toll to more than 422,000.