Israel becomes one of the few countries to impose a second nationwide lockdown. In the U.S., Joe Biden tries to focus the campaign on President Trump’s virus performance.

The Centers for Disease Control and Prevention on Friday reversed a recommendation suggesting that people who have had close contact with a person infected with the coronavirus do not need to get tested if they have no symptoms.

The change comes after widespread criticism of the earlier guideline, as well as reporting from The New York Times that the recommendation came from political appointees in the Trump administration and skipped the agency’s usual rigorous scientific review.

The Times reported Thursday that the guideline was posted on the C.D.C. website despite strenuous objections from its scientists.

The previous phrasing, which suggested asymptomatic people who have had close contact with an infected individual “do not necessarily need a test,” now clearly instructs them: “You need a test.”

Public health experts welcomed the change as consistent with research showing that people without symptoms can spread the virus to others. Some research has suggested that they are actually most likely to transmit to others starting around a day before the onset of symptoms, when the viral load can be the highest.

“It’s good to see science and evidence taking a front seat for a change,” said Scott Becker, chief executive of the Association of Public Health Laboratories.

And Dr. Ashish Jha, dean of the School of Public Health at Brown University, said, “I’m thrilled to see it, it clearly needed to be done.”

The original guidance, posted on Aug. 24, drew sharp criticism even from the C.D.C.’s partners, including the Infectious Diseases Society of America, which urged its members to continue testing people without symptoms.

In a statement Friday, Dr. Thomas File, the organization’s president, said “the return to a science-based based approach to testing guidance from the Centers for Disease Control and Prevention is good news for public health.”

Emails obtained by The Times illustrate how a top Trump health official and his science adviser attempted to browbeat career officials at C.D.C. at the height of the pandemic, challenging the science behind their public statements and attempting to silence agency staff.

The Times reported last week on pressures on the C.D.C. to change its weekly disease reports exerted by Michael R. Caputo, a former Trump campaign official installed by the White House in April as the top spokesman for the Health and Human Services Department, and his science adviser, Dr. Paul Alexander, a part-time assistant professor of health research methods. Mr. Caputo went on medical leave this week.

The emails, obtained by Noah Weiland of The Times, conform with what current and former C.D.C. officials called a five-month campaign of bullying.

One of the emails was written after Dr. Anne Schuchat, a 32-year veteran of the C.D.C., appealed to Americans to wear masks and warned, “We have way too much virus across the country.”

“She is duplicitous,” Dr. Alexander wrote to Mr. Caputo. He asked Mr. Caputo to “remind” Dr. Schuchat that during the H1N1 swine flu outbreak in 2009, thousands of Americans had died “under her work.”

Of Dr. Schuchat’s assessment of Covid-19’s dangers, Dr. Alexander fumed, wrongly, “The risk of death in children 0-19 years of age is basically 0 (zero) … PERIOD … she has lied.”

Mr. Caputo forwarded that assessment to Dr. Robert R. Redfield, the C.D.C. director. When a member of the health department’s White House liaison office called the agency to ask questions about Dr. Schuchat’s biography, C.D.C. officials were left with the impression that some in Washington could have been searching for ways to fire her.

Far from hiding what they knew about the virus’s danger, as Bob Woodward’s new book contends President Trump was doing, the emails seem to indicate that aides in Washington were convinced of their own rosy prognostications, even as coronavirus cases were shooting skyward.

Mr. Trump sought on Friday to recalibrate his assurances on vaccine availability, acknowledging that authorized doses might not be widely available in the United States until next spring even if distribution starts earlier.

Speaking at the White House, Mr. Trump said that once a vaccine is authorized, “Distribution will begin within 24 hours after notice.” He added, “We will have manufactured at least 100 million vaccine doses before the end of the year. And likely much more than that. Hundreds of millions of doses will be available every month and we expect to have enough vaccines for every American by April.”

The president had said earlier that a vaccine would be available to “the general public immediately” once it is authorized, and although he held firm on that pledge, he acknowledged that it would take perhaps months from that point to distribute vaccines to hundreds of millions of Americans.

Because of fears that Mr. Trump would interfere in the process to improve his election chances and pressure the Food and Drug Administration to approve a vaccine before it was proved safe, the chief executives of all the leading pharmaceutical companies signed a pledge two weeks ago saying they would not release any vaccines until they were sure they were safe.

Opinion polls have shown that many Americans are already hesitant about taking a vaccine that is seen to have been rushed to market by the federal government for political reasons.

Mr. Trump’s estimates of how many vaccine doses would be available this year stood in contrast to the chief science adviser for the Trump administration’s Operation Warp Speed effort, Moncef M. Slaoui, a former chairman of global vaccines for GlaxoSmithKline and a widely respected figure in the vaccine field. He and other leaders of Warp Speed were present at Friday’s news conference but not asked to comment.

In interviews with CNN and National Public Radio, Dr. Slaoui has said he expected only enough vaccine to immunize 20 million to 25 million people by year’s end. Enough to vaccinate all Americans would be ready by about the middle of next year, he said.

Dr. Slaoui has publicly said he would resign if there were political interference in the process of delivering a safe, effective vaccine.

Mr. Trump did not say which vaccine he was talking about. It is not a given that any of the eight vaccines that Operation Warp Speed is supporting will win approval, although Dr. Slaoui has said he has high hopes for several of them and believes that some may approach 90 percent efficacy; that would be significantly more than the 50 percent efficacy that the F.D.A. has said it will accept as a minimum.

A number of the leading Covid-19 vaccines under development will need to be kept at temperatures as low as minus 112 degrees Fahrenheit from the moment they are bottled to the time they are ready to be injected into patients’ arms.

That will not be easy. Vaccines may be manufactured on one continent and shipped to another. They will go from logistics hub to logistics hub before ending up at the hospitals and other facilities that will administer them.

And while no vaccine has yet been approved by health officials in the United States, preparations for a mass-vaccination campaign are gearing up. The U.S. military and a federal contractor are expected to play a role in coordinating the distribution. But a hodgepodge of companies are scrambling to figure out how to keep hundreds of millions of doses of a vaccine very, very cold.

Planes, trucks and warehouses will need to be outfitted with freezers. Glass vials will need to withstand icy climes. Someone will need to make a lot more dry ice.

Of the three vaccines that have advanced to Phase 3 trials, two — one made by Moderna and the National Institutes of Health, the other by Pfizer and BioNTech — need to be kept in a near constant deep freeze. (They are made with genetic materials that fall apart when they thaw.) Another leading vaccine candidate, being developed by AstraZeneca and Oxford University, must be kept cool but not frozen.

McKesson, a major drug distributor, won a major federal contract last month to help distribute a coronavirus vaccine. Much of the work, however, will fall to companies outside the medical and drug industries. The major U.S. logistics companies, including UPS and FedEx, already have networks of freezers that they use to ship perishable food and medical supplies. The companies have experience shipping vaccines for other illnesses, including the seasonal flu.

Almost 1,000 Las Vegas casino employees have tested positive for the virus, according to reports on Thursday by two major casino operators. Wynn Resorts, which operates the Wynn Las Vegas and Encore on the Vegas strip, said 548 employees had tested positive. And Las Vegas Sands Corp, with The Venetian and Palazzo, reported 424 cases.

The announcements came as bars in Clark County, which includes Las Vega, were given permission to reopen on Sunday night at midnight. Both companies said testing began on May 11, but the vast majority of positive results have come since the casinos reopened in June. Wynn said in the most recent round of testing only one of 285 tests was positive.

As of Friday afternoon, the state has had more than 74,800 cases and more than 1,500 deaths, of which the vast majority were in Clark County, according to a New York Times database. The area is considered an “elevated disease transmission” county based on the state’s criteria, which includes tests per day, positivity rate and case rate.

The daily number of new cases peaked in late July, forcing the state to pull back efforts to reopen and continuing the hardship on its tourism-based economy.

Matt Maddox, chief executive of Wynn Resorts, said in a statement Thursday that the company had employed 10 full-time contact tracers and that hotel guests with possible exposure or symptoms are tested in their rooms. Six guests have tested positive out of more than 500,000 who have visited the casino since it reopened in early June, the statement said.

“Our goal,” Mr. Maddox said, “is to make Wynn Las Vegas the safest place our guests and employees can go outside of their own homes.”

In recent weeks, a state task force has allowed activities to resume as long as the numbers have been trending in the right direction, said Brian Labus, an epidemiologist at the at the University of Nevada, Las Vegas School of Public Health, who serves on the governor’s medical advisory team.

“They’re taking in more factors than just the health considerations — they’re one of the hardest-hit economies in the country,” Professor Labus said. “There’s things that we would do that other places may not, because if you shut down tourism, you shut down the entire state.”

The task force voted on Thursday to allow Clark County and Elko County, which also has an “elevated disease transmission” status, to open bars. Bars must operate at half-capacity and all patrons and employees must wear masks unless they are “actively eating, drinking, or smoking,” according to state guidelines.

A spokesman for Wynn said that 98 percent of employees who tested positive had told contact tracers that they knew where they had been infected and it was not at the workplace. Experts questioned whether it was possible to definitively tell where transmission occurred. The company said 15,051 employees had been tested, and it reported a positivity rate of 3.6 percent.

Obviously we’re looking very carefully at the spread of the pandemic, as it evolves over the last few days, and there’s no question as I’ve said for several weeks now, that we could expect — that we are now seeing a second wave coming in, we’ve seen it in France, you see it in Spain, across Europe. It’s been, absolutely, I’m afraid inevitable, that we would see it in this country. So Monday we brought in the measures that we did, the “Rule of Six,” to really try to restrict what people are doing, and to bring in a new buffer just make that absolutely clear, the “Rule of Six” — six indoors, maximum, six outdoors maximum. But the crucial thing is, at the same time, to observe the basic rules on social distancing — hands, face, space. That’s what is everybody’s got to do if we’re going to continue to beat this thing. I don’t want to get into a second national lockdown at all. Last thing anybody wants. I don’t want to go into a bigger lockdown measures at all. We want to keep schools open.

Roughly 10 million people in England face new virus restrictions amid a spike in new cases. The country’s once-vaunted testing system is on the verge of collapse. And Prime Minister Boris Johnson of Britain is contemplating closing restaurants and pubs to corral a second surge in Europe’s worst-affected country.

Mr. Johnson is also facing rising anger over his contradictory edicts. Over the summer, he offered people a government-subsidized discount at restaurants and pubs but spoke bluntly on Friday about the virus advancing across Britain.

“There’s no question, as I’ve said for several weeks now, that we could expect and we are now seeing a second wave coming in,” Mr. Johnson said in a television interview. “I don’t think anybody wants to go into a second lockdown, but clearly when you look at what is happening, you’ve got to wonder whether we need to go further than” the new law forbidding gatherings of more than six.

“It does seem ironic,” said Jonathan Ball, a professor of molecular virology at the University of Nottingham, “after encouraging mass attendance at pubs, cafes and restaurants,” that restrictions on those activities were being considered.

The R number, a measure of how many people on average a single patient will infect, rose to between 1.1 and 1.4, the government said on Friday. Any number over 1 is a worrisome indication that the epidemic is growing.

In the week ending Sept. 10, there were roughly 6,000 new daily cases outside hospitals and nursing homes in England, the government’s official statistics authority estimated, nearly a doubling from the week before.

More than 30 million cases have been reported worldwide as of Friday morning, according to a New York Times database. India, in particular, has recently contributed significantly to the count, having added more than 93,000 new cases a day on average over the last week.

Prime Minister Scott Morrison of Australia on Friday raised the cap on international arrivals to 6,000 from 4,000 people a week, after critics accused him of leaving citizens stranded overseas. Approximately 24,000 Australians are outside the country, Mr. Morrison said, adding that he hoped many of them would be home by Christmas. The state of Queensland also said that it would allow flights to resume to and from the Australian Capital Territory next week. Australia has reported 297 new cases in the past week, and its second-largest city, Melbourne, remains under lockdown.

New Zealand recorded no new cases of the virus on Friday for the first time in more than a month, after an outbreak in Auckland in August threatened the progress against the virus. The country now has just 70 active cases. Of those, 37 are from community transmission and the rest are from overseas arrivals.

Sciences Po, one of France’s most prestigious universities, is closing its Paris campus for 14 days after a significant number of students tested positive for the virus. Classes will be held online. And Nice, the country’s fifth-largest city, banned social gatherings of more than 10 people in parks, gardens and beaches to try to slow the spread of the virus. Cases have surpassed 50 per 100,000 people in Nice, where a third of the residents are considered elderly. The sale and consumption of alcohol is also forbidden after 8 p.m. and bars will have to close at 12:30 a.m. Bordeaux and Marseille are facing similar rules.

President Rodrigo Duterte of the Philippines has extended a national state of emergency until September 2021. Last month, the Philippine Congress extended Mr. Duterte’s emergency powers to address the pandemic, and it passed legislation allocating support for low-income households and people who lost their jobs because of the crisis.

A ban on nonessential travel between the United States and Canada that was set to expire Sept. 21 has been extended to Oct. 21, Mark A. Morgan, the acting commissioner of U.S. Customs and Border Protection, announced in a tweet on Friday. The restriction has been repeatedly extended since it was put in place in March.

China’s CanSino Biologics and a military-backed research institute are preparing to start clinical trials of a two-dose vaccine regimen after scientists raised concerns that their current one-dose treatment failed to produce a strong enough immune response. The vaccine was promoted by Chinese state media as a front-runner in the vaccine race but struggled to get Phase 3 trials started in Canada.

As millions of American students have returned to school across the country in recent weeks, cases have forced quarantines and shutdowns, and a few states, including Texas and Ohio, have rolled out online dashboards to track cases in schools.

Determining the impact of school openings on the broader trajectory of the pandemic has been difficult as reporting from states and districts has been spotty and inconsistent, with officials in some places refusing to reveal case numbers.

The number of cases reported by schools will almost certainly be an undercount, experts say, because children in particular are likely to be asymptomatic when carrying the virus, and are unlikely to be tested in the absence of symptoms.

A high school student in Attleboro, Mass., went to the first day of in-person classes on Monday despite testing positive days earlier. Roughly 30 people at Attleboro High School who came into contact with the student are now in quarantine. Attleboro’s mayor said that the student’s parents knew he had tested positive when they sent him to school.

Police in Mitchell, S.D., removed a man from a school board meeting for refusing to put on a mask in violation of district policy. Several speakers later criticized the mask mandate and asked why parents had not been surveyed about whether they supported it. “A survey wouldn’t change my mind,” one member of the school board said.

Northeastern University in Boston has agreed to refund most of the fall semester tuition of 11 first-year students who were dismissed earlier this month for violating the school’s coronavirus rules by gathering in a room without masks or social distancing.

More than 1,000 students and employees at Liberty University in Lynchburg, Va., have been instructed to quarantine, according to the school’s coronavirus dashboard. There are currently 141 active cases of the virus at the school, one of the world’s largest private evangelical universities, with 137 infections among students and four among employees.

New York City will soon let restaurants add a temporary charge of up to 10 percent as help in the pandemic, (though not for takeout or delivery), as long as it is clearly noted on menus.

The charge, which comes before tax, will be allowed until 90 days after the date, yet to be determined, when indoor dining is fully restored. (Indoor dining resumes on Sept. 30 at only 25 percent capacity.)

But in interviews, many restaurant owners said they weren’t ready to add the new surcharge, especially at the full 10 percent.

A growing group of restaurateurs and activists urging the City Council to add some restrictions to the surcharge that will improve conditions for workers, such as limiting it to restaurants that pay their entire staff, including servers, at least the full city minimum wage or above, as he does.

New York City’s indoor pools will be allowed to reopen on Sept. 30, the mayor said Friday, so long as they do not exceed 33 percent capacity and follow all other city and state guidelines. Saunas, steam rooms and indoor spa pools in gym facilities remain closed.

Mask compliance has been generally high in most indoor settings in New York City, but confrontations have been playing out on buses, and dozens of drivers have been attacked after trying to enforce the rules.

The state’s Department of Motor Vehicles is expanding online services, the governor said Friday. A pilot program will offer digital written tests for learners’ permits for passenger cars and motorcycles. Another pilot program will allow residents of counties with state-run D.M.V. offices to register their vehicles.

As Israelis prepare to celebrate the holiest days on the Jewish calendar under a fresh lockdown, organizing prayer services is proving to be more of a mathematical brainteaser than a spiritual exercise.

Rabbis must arrange worshipers into clusters of 20 to 50, separated by dividers, determining the size of the groups based on complex calculations involving local infection rates, and how many entrances and square feet their synagogues have. Masks will be required, and many seats will have to remain empty.

With the virus rampaging again, Israel became one of the few places in the world to go into a second lockdown. The rules took effect on Friday, on the eve of Rosh Hashana, the Jewish New Year.

The government has issued a list of restrictions — along with a plethora of exemptions that many criticize as a formula for confusion and noncompliance.

“These are not the holidays we were hoping for,” said Rabbi Kenneth Brander, the president of Ohr Torah Stone, an Israel-based Jewish education group with emissaries around the world. “The fragility of life is upon us, but I see people rising to the occasion.”

The three-week national lockdown was timed to coincide with the Rosh Hashana and Yom Kippur holy days and the festival of Sukkot, in the hope of causing less economic damage because business slows down in any case around the holidays. It was also aimed at preventing large family meals that could become petri dishes for the virus.

Israel successfully limited the spread of the virus in the spring, but the number of cases, when adjusted for population, has risen to among the highest in the world. The country has had more than 300 confirmed new cases per 100,000 people over the last week — more than double the rate in Spain, the hardest-hit European country, and quadruple that of the United States.

The holiday will also be transformed, of course, for Jews outside of Israel. Across the United States, Jewish people are grappling with how to mark the high holidays, traditionally a time to contemplate themes of repentance, reckoning and renewal.

Many synagogues have focused on preparing elaborate online productions. (Though not the Orthodox communities, who are taught to eschew technology on the Sabbath.)

“I feel like I have learned how to be a 1950s live television producer,” said Serge Lippe, the senior rabbi of the Brooklyn Heights Synagogue, a reform congregation. “I have been running a show and producing cuts and all kinds of things I have never had to think about.”

Six members of a team directing the firefighting efforts in the Pacific Northwest went into temporary quarantine after a member of a resupply crew tested positive, the authorities said.

The test result, which led to a shutdown of a command post in Washington State for about an hour on Thursday, came amid longstanding worries about the current hazards of sending thousands of firefighters into close-quarter operations.

The six members of the fire management team deployed about 40 miles northeast of Portland, Ore., were quarantined as commanders attempted to determine who might have been exposed, officials said. One remained in isolation on Friday.

“Fire season is already an unbelievable stress — on resources and the firefighters,” said Washington’s commissioner of public lands, Hilary Franz, who visited the affected camp. “You add in a deadly pandemic, it makes it all the more challenging.”

The arrival of virus to the West Coast’s frontline firefighting forces has added yet another complication to the record-breaking fires that have left crews exhausted and potentially vulnerable. Thousands of firefighters, many of whom have traveled in from other regions, remain clustered in camps across open fields and throughout the remote backcountry where some of the vast blazes remain largely uncontained.

A rapid-containment strategy ordered by the U.S. Forest Service to take the pandemic into account has not prevented a wildfire outbreak of historic proportions. More than 3.4 million acres have burned in California, hundreds if not thousands of homes were destroyed in Oregon, and fires continue to burn in Washington State.

Officials in North Dakota reported more than 500 new cases on Friday, a single-day record. More cases have been announced in North Dakota over the last week than in any other seven-day stretch of the pandemic.

U.S. customs officials in Boston seized a trove of some 20,400 counterfeit N95 respirator masks from Hong Kong this month, the agency said in a statement. The shipment, with an estimated value of $163,200, is the latest example of scammers attempting to profiteer from fake personal protective equipment.

Arguments ended Thursday in what may be the country’s longest-ever virtual jury trial, an asbestos-related lawsuit filed in Alameda County, Calif. Defendants complained that jurors appeared to be sleeping, working out and caring for children during the trial and that they got chummy with the plaintiff, helping him create a virtual backdrop for his video feed.

This week, Tucker Carlson hosted a Chinese virologist named Dr. Li-Meng Yan on his Fox News show. Dr. Yan, who has made regular appearances in conservative media outlets this year, claimed to have “solid scientific evidence” that the novel coronavirus is “not from nature,” that it was created in a lab under a Chinese military program, and that it was spread intentionally outside China as part of a biowarfare plot.

But none of Dr. Yan’s claims are justified by the scientific evidence. The vast majority of scientists who have studied the coronavirus agree that it originated naturally, and spread to humans from an animal species, such as a bat. And although scientists can’t rule out the possibility that the virus originated in a lab studying animals such as bats, it is vanishingly unlikely that it was genetically engineered and intentionally released.

Still, Dr. Yan’s explosive claims quickly went viral on social media. A video clip of her Tucker Carlson show appearance has gotten two million views on YouTube, and nearly a million views on Facebook. Conservative influencers like Dennis Prager, Mike Huckabee and David J. Harris Jr. have also shared her claims.

On Wednesday, Facebook and Instagram began flagging posts from Mr. Carlson’s show about Dr. Yan’s claims, saying that they repeated information about the coronavirus “that multiple independent fact checkers say is false.”

Twitter suspended Dr. Yan’s account on Wednesday, which provoked another round of viral posts, including accusations by Senator Josh Hawley of Missouri that Twitter was “openly on the side of Beijing.”

Public health authorities, including the World Health Organization and the Centers for Disease Control and Prevention, have also noted that while the exact source of the virus is still unknown, the evidence strongly suggests a natural origin. “The sequences from U.S. patients are similar to the one that China initially posted, suggesting a likely single, recent emergence of this virus from an animal reservoir,” explained a post on the C.D.C.’s website.

Reporting was contributed by Livia Albeck-Ripka, Peter Baker, Alexander Burns, Sarah Cahalan, Julia Carmel, Shaila Dewan, Sydney Ember, Nicholas Fandos, Antonella Francini, David Gelles, Denise Grady, Ruth Graham, Katie Glueck, Christina Goldbaum, Jason Gutierrez, Mike Ives, Andrea Kannapell, Isabel Kershner, Apoorva Mandavilli, Donald G. McNeil Jr., Constant Méheut, Zachary Montague, Kevin Roose, Anna Schaverien, David Segal, Michael D. Shear, Mitch Smith, Liam Stack, Matt Stevens, Katie Thomas, Glenn Thrush, Amber Wang, Sui-Lee Wee, Noah Weiland and Rachel Wharton.


News – Covid-19 Live Updates: After Criticism, C.D.C. Reverses Guidelines on Testing People Who Were Exposed