Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, has stumbled in explaining her policy decisions.WASHINGTON — Two days before Christmas, with the Omicron variant driving a near-vertical rise in new coronavirus cases, the director of the Centers for Disease Control and Prevention alerted the White House that she planned to recommend that people infected with the virus isolate for five days instead of 10.The director, Dr. Rochelle P. Walensky, had faced previous criticism for issuing recommendations that confused the public and in some cases caught the White House off guard. Determined to avoid that this time, she briefed other top Biden health officials on her proposal so they would all be on the same page, according to two people familiar with her actions.It did not work out that way. Dr. Anthony S. Fauci, the nation’s top infectious disease expert, and Dr. Vivek H. Murthy, the surgeon general, were concerned that the new guidance did not urge people to get a negative Covid test before ending their isolation. After the new recommendation became public, they both took issue with it on national television, saying they expected the C.D.C. to clarify its advice.On Wednesday, nine days after the guidance was issued and a day after it was slightly modified to include some advice on testing, the C.D.C. was still having a hard time explaining itself. “How do you expect people to keep track of what they can and can’t do?” a CNN reporter demanded of Dr. Walensky at a White House briefing.It was a familiar refrain.President Biden came into office vowing to restore public trust in the C.D.C. after the Trump White House had tied the agency’s hands and manipulated its scientific judgments on the pandemic for political ends. Yet in his first year of battling the coronavirus, Mr. Biden has presided over a series of messaging failures that have followed a familiar pattern, with Dr. Walensky and her team making what experts say are largely sound decisions, but fumbling in communicating them to America.Dr. Walensky, a highly regarded infectious disease expert from Boston with no prior government experience, insisted in February that schools must keep students six feet apart; in March, she said three feet was enough. She said in February that teachers did not need to be vaccinated to reopen schools; the White House said the next day that she was speaking “in her personal capacity.”In May, she said that vaccinated people generally did not need to wear masks in public, a sudden change that flummoxed state health officials. Two months later, she reversed that guidance after it was shown that vaccinated people could still transmit the virus.With the virus throwing one curveball after another, changing advice from the C.D.C. is a given. But Dr. Walensky’s critics say the C.D.C.’s recommendations are sometimes so confusing or abruptly modified that they seem more like drafts than fully vetted proclamations.“I don’t think that the C.D.C. guidelines were significantly wrong,” Dr. Tom Frieden, the agency’s director under former President Barack Obama, said of the latest recommendations on isolation for those with Covid. But he added, “I think the way they were released was very problematic.”The crux of the problem, several administration officials said, is a failure by the C.D.C. and the Biden administration’s messaging experts to work in concert. Who is to blame for that is a matter of debate. Dr. Walensky’s critics say she is not collaborative enough, too often springing decisions on other federal officials who then struggle to defend them in public. Her defenders say she strives to coordinate, but that it is not her job to ensure consensus across the entire administration.Some suggest the White House has gone too far in its hands-off, let-the-scientists-rule approach, leaving a vacuum of leadership and forcing ad-hoc coordination between the various public health agencies. That has been exacerbated by a health secretary, Xavier Becerra, who receives routine briefings from scientists but does not settle interagency disputes about the pandemic response.Dr. Fauci, the administration’s best-known spokesman on the pandemic, has further muddied the waters at times, publicly contradicting the C.D.C. as he did this week or making statements he has later walked back.He said in late December, for instance, that a vaccination requirement for domestic airline passengers should be seriously considered, leaving the White House to field a flurry of questions on a policy it was not prepared to recommend. Later, he said a mandate was unlikely.On Wednesday, Jen Psaki, the White House press secretary, said it was OK for the C.D.C. to modify its guidance, adding that, for one thing, “if they hadn’t changed their recommendations over the course of time, schools would probably be closed across the country.”But even some within Dr. Walensky’s own agency agree that the C.D.C.’s public pronouncements on the pandemic have repeatedly fallen short, long after experts say the agency should have mastered clear and concise public messaging on the worst public health crisis in a century.The handling of the isolation guidance was a case study in how to confuse the public. And the controversy is not over: health experts continued on Wednesday to criticize the C.D.C.’s decision not to recommend a negative test before people with Covid end a five-day isolation.“The new recommendations on quarantine and isolation are not only confusing, but are risking further spread of the virus,” the American Medical Association said in a statement on Wednesday.Dr. Walensky said that she and career staff finished devising the guidance over the Christmas weekend. Officials decided that people with Covid-19 could end their isolation after five days instead of 10 if they were asymptomatic or if their symptoms were “resolving,” meaning no fever for 24 hours. The agency said 85 to 90 percent of viral transmission occurred within that initial five-day period. Dr. Walensky verbally briefed other senior federal officials on the new guidance at least twice that weekend, defending her decision not to recommend that people test negative first. One person familiar with Dr. Walensky’s account said no one raised serious objections.But Dr. Fauci said in an interview that he did not see the final version before it was released. Others familiar with the situation said the C.D.C. did not share it before posting it publicly on Dec. 27.Although the Food and Drug Administration now typically holds a news briefing after major regulatory moves on Covid vaccines or treatments, the C.D.C. held no briefing on the decision. Indeed, it has not held regular news conferences since former President Donald J. Trump put an end to them in early 2020. Dr. Walensky does take questions at least once a week during the White House’s pandemic news briefings.The agency’s minimalist explanation immediately set off a fraught debate: Why not recommend a negative test before ending isolation? Was it because tests were in short supply? Was the agency shortening the isolation period to keep the economy running instead of for science-based reasons?“Where the messaging gets muddled is where it is unclear what is driving the decision,” said Dr. Celine R. Gounder, an infectious disease expert at Bellevue Hospital Center in New York who considers Dr. Walensky a mentor.Dr. Gounder said she and other experts suspected that a shortage of tests was behind the decision, and that if Dr. Walensky had said so, “the public health community would have been more understanding.” Dr. Walensky said Wednesday that the guidance had “nothing to do with the shortage of available tests.”In an interview with The Times last week, Dr. Walensky said the advice was carefully crafted with a team of career officials. She said rapid tests were meant to diagnose infection, not predict the risk of spreading it — a position echoed by the F.D.A., which regulates the tests.The Coronavirus Pandemic: Key Things to KnowCard 1 of 6The global surge.

The White House’s move is part of a nascent campaign to inoculate the world, and came as President Biden faced intense pressure to do more.WASHINGTON — President Biden, under pressure to aggressively address the global coronavirus vaccine shortage, will announce as early as Thursday that his administration will buy 500 million doses of the Pfizer-BioNTech vaccine and donate them among about 100 countries over the next year, according to people familiar with the plan.The White House reached the deal just in time for Mr. Biden’s eight-day European trip, which is his first opportunity to reassert the United States as a world leader and restore relations that were badly frayed by President Donald J. Trump.“We have to end Covid-19, not just at home, which we’re doing, but everywhere,” Mr. Biden told American troops after landing at R.A.F. Mildenhall in Suffolk, England. “There’s no wall high enough to keep us safe from this pandemic or the next biological threat we face, and there will be others. It requires coordinated multilateral action.”People familiar with the Pfizer deal said the United States would pay for the doses at a “not for profit” price. The first 200 million doses will be distributed by the end of this year, followed by 300 million by next June, they said. The doses will be distributed through Covax, the international vaccine-sharing initiative.Mr. Biden is in Europe for a week to attend the NATO and Group of 7 summits and to meet with President Vladimir V. Putin of Russia in Geneva. He is likely to use the trip to call on other nations to step up vaccine distribution.In a statement on Wednesday, Jeffrey D. Zients, the White House official in charge of devising a global vaccination strategy, said Mr. Biden would “rally the world’s democracies around solving this crisis globally, with America leading the way to create the arsenal of vaccines that will be critical in our global fight against Covid-19.”The White House is trying to spotlight its success in fighting the pandemic — particularly its vaccination campaign — and use that success as a diplomatic tool, especially as China and Russia seek to do the same. Mr. Biden has been insistent that, unlike China and Russia, which have been sharing their vaccines with dozens of countries, the United States will not seek to extract promises from countries receiving American-made vaccines.AstraZeneca vaccines being delivered in Mexico City under Covax, the international vaccine-sharing initiative. The program will distribute the 500 million doses that the Biden administration will donate.Henry Romero/ReutersThe 500 million doses still fall far short of the 11 billion the World Health Organization estimates are needed to vaccinate the world, but significantly exceed what the United States has committed to share so far. Other nations have been pleading with the United States to give up some of its abundant vaccine supplies. Less than 1 percent of people are fully vaccinated in a number of African countries, compared with 42 percent in the United States and the United Kingdom.Advocates for global health welcomed the news, but reiterated their stance that it is not enough for the United States to simply give vaccine away. They say the Biden administration must create the conditions for other countries to manufacture vaccines on their own, including transferring technology to make the doses.“The world needs urgent new manufacturing to produce billions more doses within a year, not just commitments to buy the planned inadequate supply,” Peter Maybarduk, the director of Public Citizen’s Access to Medicines program, said in a statement. He added, “We have yet to see a plan from the U.S. government or the G7 of the needed ambition or urgency to make billions more doses and end the pandemic.”The deal with Pfizer has the potential to open the door to similar agreements with other vaccine manufacturers, including Moderna, whose vaccine was developed with American tax dollars — unlike Pfizer’s. In addition, the Biden administration has brokered a deal in which Merck will help produce Johnson & Johnson’s vaccine, and those doses might be available for overseas use.The United States has already contracted to buy 300 million doses of the Pfizer-BioNTech vaccine, which requires two shots, for distribution in the United States; the 500 million doses are in addition to that, according to people familiar with the deal.Neither Pfizer nor administration officials would say what the company is charging the government for the doses. Pfizer is also offering the Biden administration an option to buy even more doses at cost to be donated overseas, according to several people familiar with the arrangement.For Pfizer, the decision to sell the Biden administration so much supply without making a profit is a significant step.Its vaccine accounted for $3.5 billion in revenue in the first three months of this year, nearly a quarter of Pfizer’s total revenue. By some estimates, the firm earned roughly $900 million in pretax profits from the vaccine during the first quarter.But the company also faced criticism that it was disproportionately aiding wealthy nations, even though Pfizer’s chief executive, Albert Bourla, had promised in January to help ensure that “developing countries have the same access as the rest of the world.”For Mr. Biden, the agreement shows that his administration is willing to dip more deeply into the nation’s treasury to help out poorer countries.Last week, Mr. Biden said the United States would distribute 25 million doses this month to countries in the Caribbean and Latin America; South and Southeast Asia; Africa; and the Palestinian territories, Gaza and the West Bank.Those doses are the first of 80 million that Mr. Biden pledged to send abroad by the end of June; three-quarters of them will be distributed by Covax. The rest will go toward addressing pressing and urgent crises in places like India and the West Bank and Gaza, administration officials have said. Many of the 80 million doses were made by AstraZeneca and are still tied up in a complex review by the Food and Drug Administration.A popup vaccine site in Brooklyn in May. About 64 percent of adults in the United States have received at least one shot.James Estrin/The New York TimesMr. Biden has also committed to supporting a waiver of an international intellectual property agreement, which would make it harder for companies to refuse to share their technology. But European leaders are blocking the proposed waiver, and pharmaceutical companies are strongly opposed to it. The World Trade Organization’s Council for Trade-Related Aspects of Intellectual Property Rights is meeting this week to consider the waiver.The president’s promise of vaccines for the global market comes as he prepares to meet on Thursday with Prime Minister Boris Johnson of Britain, who has called on leaders to commit to vaccinating everyone in the world by the end of 2022. Mr. Biden’s announcement is likely to be welcome news for Mr. Johnson, whose critics have questioned where the money will come from to meet his pledge.“The truth is that world leaders have been kicking the can down the road for months — to the point where they have run out of road,” Edwin Ikhouria, the executive director for Africa at the ONE Campaign, a nonprofit aimed at eradicating global poverty, said in a statement on Wednesday.About 64 percent of adults in the United States are at least partly vaccinated, and the president has set a goal of bringing that number up to 70 percent by July 4. The pace of vaccination has dropped sharply since mid-April, leading the Biden administration to pursue a strategy of greater accessibility and incentives to reach Americans who have not yet gotten shots.In spite of those efforts, there are unused vaccine doses that could go to waste. Once thawed, doses have a limited shelf life and millions could begin expiring within two weeks, according to federal officials.Providing equitable access to vaccines has become one of the most intractable challenges to reining in the pandemic. Wealthier nations and private entities have pledged tens of millions of doses and billions of dollars to shore up global supplies, but the disparity in vaccine allocations so far has been stark.Dr. Tedros Adhanom Ghebreyesus, the director general of the World Health Organization, warned this week that the world was facing a “two-track pandemic,” in which countries where vaccines are scarce will struggle with virus cases even as better-supplied nations return to normal.Those lower-income countries will be largely dependent on wealthier ones until vaccines can be distributed and produced on a more equitable basis, he said.Daniel E. Slotnik

The White House’s move is part of a nascent campaign to inoculate the world, and came as President Biden faced intense pressure to do more.WASHINGTON — President Biden, under pressure to aggressively address the global coronavirus vaccine shortage, will announce as early as Thursday that his administration will buy 500 million doses of the Pfizer-BioNTech vaccine and donate them among about 100 countries over the next year, according to people familiar with the plan.