The agency’s top medical official was responding to rumors that Suni Williams had lost an unusual amount of weight during an extended stay in orbit.Suni Williams, a NASA astronaut currently on the International Space Station, is healthy and not suffering from any medical problems, NASA’s top medical officer said on Thursday.The unusual pronouncement was prompted by news articles suggesting that Ms. Williams was experiencing health problems during an unplanned extended stay in orbit. That in turn set off widespread rumors on social media.Ms. Williams, 59, addressed the issue directly on Tuesday during an interview with New England Sports Network.“I think there’s some rumors around outside there that I’m losing weight and stuff,” she said. “No, I’m actually right at the same amount.”Ms. Williams is one of the two astronauts whose stay at the space station was stretched from eight days to eight months because of propulsion problems with the Boeing Starliner spacecraft that took them there in June. While taking pains to insist that Ms. Williams and Butch Wilmore, the other astronaut, were not stranded, NASA decided that Starliner would return to Earth empty and that Ms. Williams and Mr. Wilmore would join the space station crew until February. They are to head home on a SpaceX Crew Dragon spacecraft instead.A photograph that NASA released in late September showed Ms. Williams and Mr. Wilmore making pizza on the space station. Ms. Williams’s face appeared sunken and thin.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe.

An extensive examination of medical data gathered from the private Inspiration4 mission in 2021 revealed temporary cognitive declines,Space changes you, even during short trips off the planet.Four people who spent three days off Earth in September 2021 experienced physical and mental changes that included modest declines in cognitive tests, stressed immune systems and genetic changes within their cells, scientists report in a package of papers published on Tuesday in the journal Nature and several other related journals.Almost all of what changed in the astronauts returned to normal after they splashed down on Earth. None of the alterations appeared to pose a showstopping caution for future space travelers. But the results also highlighted how little medical researchers know.Christopher Mason, a professor of genomics, physiology and biophysics at Weill Cornell Medicine in New York City and one of the leaders of the research, called the collection of papers and data “the most in-depth examination we’ve ever had of a crew” as he spoke during a news conference on Monday.The four astronauts traveled on a mission, known as the Inspiration4, which was the first trip to orbit where not one of the crew members was a professional astronaut. Jared Isaacman, a billionaire entrepreneur, led the mission. Instead of bringing friends along, he recruited three travelers who represented a wider swath of society: Hayley Arceneaux, a physician assistant who survived cancer during her childhood; Sian Proctor, a community college professor who teaches geoscience; and Christopher Sembroski, an engineer.The Inspiration4 crew members consented to participating in medical experiments — collecting samples of blood, urine, feces and saliva during their flight — and to allowing the data to be cataloged in an online archive known as the Space Omics and Medical Atlas, or SOMA, which is publicly available.Although the data is anonymous, that does not provide much privacy because there were only four crew members on Inspiration4. “You could probably figure out who is who, actually,” Dr. Proctor said in an interview.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe.

Dr. Anthony S. Fauci, President Biden’s top medical adviser for Covid-19, sounded cautiously optimistic on Sunday that the current Omicron wave was peaking nationally in the United States and that the coronavirus cases could fall to manageable levels in the coming months.“What we would hope,” Dr. Fauci said during an appearance on ABC’s “This Week,” “is that, as we get into the next weeks to month or so, we’ll see throughout the entire country the level of infection get to below what I call that area of control.”That did not mean eradicating the virus, Dr. Fauci said. Infections will continue. “They’re there but they don’t disrupt society,” he said. “That’s the best case scenario.”Coronavirus cases in the United States by regionThis chart shows how reported cases per capita have changed in different parts of the country. The state with the highest recent cases per capita is shown.

When he announced Inspiration4 in February, Mr. Isaacman said he wanted it to be more than an extraterrestrial jaunt for rich people like him. He reached out to St. Jude Children’s Research Hospital in Memphis, which treats children at no charge and develops cures for childhood cancers as well as other diseases. Mr. Isaacman offered to use the mission as a fund-raising vehicle for St. Jude, setting a $200 million target.“If you’re going to accomplish all those great things out in space, all that progress, then you have an obligation to do some considerable good here on Earth, like making sure you conquer childhood cancer along the way,” he said.So far, more than $130 million has been raised including the $100 million that Mr. Isaacman is personally donating to St. Jude.“We are elated with where we are from a fund-raising perspective,” said Richard C. Shadyac Jr., the president of ALSAC, the fund-raising organization for St. Jude. “I couldn’t be more pleased. We’ll continue to strive for that $200 million goal.”

When he announced Inspiration4 in February, Mr. Isaacman said he wanted it to be more than an extraterrestrial jaunt for rich people like him. He reached out to St. Jude Children’s Research Hospital in Memphis, which treats children at no charge and develops cures for childhood cancers as well as other diseases. Mr. Isaacman offered to use the mission as a fund-raising vehicle for St. Jude, setting a $200 million target.“If you’re going to accomplish all those great things out in space, all that progress, then you have an obligation to do some considerable good here on Earth, like making sure you conquer childhood cancer along the way,” he said.So far, more than $130 million has been raised including the $100 million that Mr. Isaacman is personally donating to St. Jude.“We are elated with where we are from a fund-raising perspective,” said Richard C. Shadyac Jr., the president of ALSAC, the fund-raising organization for St. Jude. “I couldn’t be more pleased. We’ll continue to strive for that $200 million goal.”

The University of Illinois says an aggressive testing program prevented deaths on and off campus during the last academic year. Now the university is contending with the Delta variant.This week is the start of a new academic year at the University of Illinois at Urbana-Champaign.After a year and a half disrupted by a pandemic, most classes will be in classrooms again, with students and professors breathing the same air. And most people will be vaccinated.The campus last week “was just really just really thriving with excitement,” said Robert J. Jones, the university’s chancellor. “Particularly among the students that did the whole year remote last year.”During that year, the university implemented an ambitious experiment in virus surveillance. It included testing, two to three times a week, of tens of thousands of students, faculty members and staff members — everyone who came to campus — in the hopes of keeping the coronavirus in check. It served as a model for other educational institutions, and some carried out similar programs.“We still know of no hospitalizations or deaths caused by spread on our campus,” said Martin D. Burke, a chemistry professor who led the university’s testing strategy. This month, ahead of this year’s return to campus, a paper by Illinois researchers is calling the Covid testing program a major success not just for the university but also the surrounding community, lowering the number of deaths from the disease.But university officials acknowledge that there were missteps and that lessons were learned. They are also grappling with the uncertainty arising from the Delta variant and how much testing and other measures will be needed.“Our hope, and our desire, is that we can end this semester, and this academic year, the way that we started, by bringing everybody back to campus with some minimal restrictions,” Dr. Jones said. “I’m very optimistic about this academic year.”Back on CampusLike many colleges, the University of Illinois shut down its campus in the spring of 2020. Officials soon started exploring whether they could bring back students in the fall.Scientists at the university developed a quick, reliable test that used saliva instead of uncomfortable nose swabs and set up a laboratory to churn out thousands of results a day.Other researchers developed a detailed computer model that indicated that twice-a-week testing of the entire university community would detect cases before the virus had spread to others.About 25,000 undergraduate students returned to campus in the fall last year. And the plan went awry almost immediatelySome students, as expected, carried the coronavirus to Champaign and Urbana, the bordering towns that are home to the campus. University officials thought that the first round of tests would identify those cases, those students would isolate themselves and infections would dwindle within a couple of weeks.Instead, the numbers surged.The computer models had assumed that students who tested positive would isolate themselves in their dorms or their off-campus housing. The researchers had not taken into account that a few infected undergraduates would continue partying, creating superspreader events.Collecting a saliva sample for coronavirus testing at the University of Illinois at Urbana-Champaign in July.Brian Cassella/Chicago Tribune, via TNS, via Alamy Live NewsThe campus was locked down, and all students were told to stay in their rooms except for essential activities, which included attending class. That ended the surge, but university administrators were mocked for not having taken into account that some students would not do what they were told.After that, the rate of Covid cases rose and fell but remained largely under control.There were more than 4,300 cases at the university in the fall semester, about three-quarters of them among undergraduates. The comprehensive testing identified many who were asymptomatic and could have spread the virus to others. The testing also revealed hot spots, and certain students were asked to undergo testing three times a week.The students went home for Thanksgiving, as had been planned, and the last part of the fall semester was taught remotely.The results were good enough that university officials decided to bring students back in January.At the beginning of the spring semester, the return of students was spread over two weeks to limit infection. And spring break was canceled and replaced by three Wednesdays off during the semester to discourage travel away from campus.The number of coronavirus infections again bumped upward as students arrived.During the spring semester, there were close to 2,000 coronavirus cases, about half as many as during the fall.Daniel J. Simons, a psychology professor who has been a critic of how his university handled the pandemic, is still not sure that the risks were worth it. “That’s a judgment call of whether it was appropriate to open or not,” he said.Over the course of the academic year, more than 5,000 undergraduates contracted Covid-19. Yet none died, or even became dangerously ill from Covid, university officials say.“We were able to keep those numbers very much under control,” Dr. Burke said. “It’s not just the total numbers that creep up over the course of a whole year. It’s avoiding those exponential outbreaks.”Even some critics, like Dr. Simons, agreed.“It could have been absolute disaster,” he said. “And it turned out not to have been.”Carl T. Bergstrom, an infectious-disease expert at the University of Washington who had praised Illinois’s plan last year, said of the final tally, “It’s good, but it’s not great.”He added, “It underscores how difficult control is in that kind of environment.”In some college towns, coronavirus outbreaks among students spilled over into the wider community. Not only did that not occur in Champaign and Urbana, university officials say, but an analysis by Dr. Burke and other scientists argues that the university’s efforts benefited people beyond campus. They reported the finding in a paper that has not yet been accepted for publication in a peer-reviewed journal.The analysis calculated the number of deaths expected for counties that are home to universities in the Big Ten athletic conference between July 6 and Dec. 23 last year, largely based on federal data but making adjustments for the social and economic makeup of the communities. For 11 of those counties, the number of Covid deaths almost matched total deaths projected by the scientists’ analysis. (Data was not available for two Big Ten universities: the University of Nebraska and the University of Maryland.)For the University of Illinois, the number of deaths in Champaign County was significantly lower than expected, the researchers said, by 14.6 percent.The Big Ten universities all imposed similar requirements for social distancing and masks, so the researchers argue that the comprehensive testing program at Illinois “uniquely resulted in a protective effect for the communities in Champaign County.”Alex Perkins, a professor of biological sciences at Notre Dame, praised the paper overall as “incredibly impressive” but said the mortality analysis was not “particularly convincing or conclusive.”A detailed analysis, Dr. Perkins said, would need to take into account the history of how the pandemic had played out in each community as well as nearby areas. “While it is an intriguing result,” he said, “I think it would take quite a lot of additional analysis to see how well that conclusion holds up.”The lessons that the University of Illinois learned have also served as a model for other institutions and communities. The university helped set up laboratories and testing programs at other universities, community colleges, public school districts, the Illinois General Assembly and private companies.Dr. Burke said he was most excited about the program in the Baltimore City public schools, where high school students are being tested weekly, one of the few school systems in the country that will employ comprehensive testing.“So I think it made a huge impact, not just here,” he said.And Illinois wasn’t the only university that implemented frequent, comprehensive testing, although it was quite likely the largest with such a diverse student population. Still, Cornell in Ithaca, N.Y., and Northeastern in Boston tried a similar approach and fared even better, with lower infection rates than Illinois’s throughout the fall.“In the end, we beat our optimistic model,” Martha E. Pollack, Cornell’s president, said earlier this year.New Academic Year, New ChallengesFor the fall, the university is requiring students, faculty members and staff members to be vaccinated. But the requirement offers a permissive loophole. It applies only to those “who are able to do so” with no requirement to explain why one might not be able to do so.Dr. Jones expects that the vast majority have complied.“We expect them to be north of 85 percent, definitely, may even be 90,” he said.Those who do not provide proof of vaccination will undergo frequent testing again — every other day for undergraduates, twice a week for graduate students and faculty and staff members. Those who do not comply are locked out of university buildings.Because of the Delta variant, masks are required indoors, even for the vaccinated.Dr. Jones said university officials had also learned from last year’s missteps, particularly a failure to focus on human dynamics and behavior.“You’ve got to always calculate that,” he said.Cornell and Northeastern have imposed similar requirements and restrictions. Dr. Pollack of Cornell said 94 percent of people at Cornell, including 97 percent of students and 99 percent of faculty members, were fully vaccinated.The Illinois campus is also planning for a resurgence of existing variants, or a more virulent one. The university has canceled reservations made at its on-campus hotel so that the rooms can be used to isolate and quarantine students if needed. The testing program can be ramped up again.“We’re still taking some of the same precautions, just to be on the safe side,” Dr. Jones said. “If the data and if the science says something different, we will turn on a dime. Absolutely.”

His work in creating a method to build complex organic molecules applied to everything from pharmaceutical manufacturing to electronics.Ei-ichi Negishi, who shared the Nobel Prize in Chemistry in 2010 for developing techniques now ubiquitous in the manufacture of pharmaceuticals, died on June 6 in Indianapolis. He was 85.His death, at a hospital, was announced by Purdue University, where Dr. Negishi was a professor for four decades. No cause was given.Dr. Negishi’s Nobel-winning research involved chemical reactions that produce complex organic compounds — large carbon-based molecules used in drugs, plastics and many other industrial materials. Coaxing one carbon atom to bond to another can be difficult, but Dr. Negishi and other chemists figured out that metals, palladium in particular, could be used as intermediary matchmakers.In these reactions, two carbon-based molecules first stick to the palladium. The palladium then disconnects from them, and the two carbons attach to each other, forming a new, larger molecule. With the palladium working as a catalyst, the organic chemistry reactions can run at lower temperatures with fewer steps, reducing cost and waste.“It just allows this enormous selectivity,” said James M. Tour, a professor of chemistry at Rice University in Houston, who was a graduate student of Dr. Negishi’s. “When you build molecules, you have to be able to work on one part of the molecule without destroying the other part.”Chemists had discovered the magic of palladium earlier, and in 1977 Dr. Negishi built on that work by using zinc compounds to ease the mingling of carbon atoms on palladium. That made the process more applicable to a wider range of reactions.“Without organic compounds, none of us can live,” Dr. Negishi said in a news conference on the day the Nobel was announced. “One of our major dream goals is to be able to synthesize any organic compounds in high yield, high efficiency.”He gave as an analogy the creating of elaborate Lego formations. “That is a pretty accurate description of what we have been trying to do,” he said.Traditionally, organic chemists largely limited themselves to molecules using the 10 or so elements found in organic compounds. Dr. Negishi said that he and others had “realized that we should make sure of the entire periodic table.”By expanding to other elements like palladium, chemists in effect increased the number of Lego pieces they could use, and that opened new avenues to synthesize the molecules they wanted to make.Dr. Negishi shared the 2010 Nobel in Chemistry with Richard F. Heck of the University of Delaware and Akira Suzuki of Hokkaido University in Sapporo, Japan.Unlike many Nobelists who say they never expected to receive the highest honor in the science world, Dr. Negishi said it was “not a major surprise” to receive an early morning phone call on Oct. 6, 2010, from the Royal Swedish Academy of Sciences, which administers the Nobels.Dr. Tour said Dr. Negishi had pursued research that he thought was Nobel-worthy. “He dreamed about it,” Dr. Tour said. “He often discussed the Nobel Prize. And what would have to be done to win this.”To that end, Dr. Negishi could be relentless. “He was extremely exacting,” Dr. Tour said. “He had no trouble pushing people to the point of tears at a blackboard.”Dr. Negishi in 2011 before presenting a talk at Purdue University. When the audience applauded him as he was introduced, he applauded the audience. John Terhune/Journal & Courier, via Associated PressDr. Tour said Dr. Negishi also had a generous side. “If anybody would walk up to his office door and knock, his door was always open,” Dr. Tour said. “And you’d usually sit down for much longer than you bargained for, because he analyzed the whole project you’re working on, not just the question that you’re asking.”Ei-ichi Negishi was born on July 14, 1935, in Changchun, China, then known as Hsinking, the capital of the Japanese-controlled part of the country, in the northeast. His family moved to Tokyo after World War II and then to a rural area outside Tokyo, where his father farmed and his mother took care of the family’s five children.After graduating from the University of Tokyo in 1958 with a bachelor of engineering degree, he worked as a research chemist at the Iwakuni Research Laboratories in Japan. By his account, he realized that he needed more academic training but felt that graduate school was financially out of reach.His fortunes changed in 1960, however, when he won a Fulbright scholarship to attend the University of Pennsylvania. After finishing his doctorate in 1963, he joined the laboratory of Herbert C. Brown at Purdue. Dr. Brown became the first Purdue faculty member to win a Nobel Prize, in 2004; Dr. Negishi was the second.“In terms of research, he is my only mentor” Dr. Negishi said of Dr. Brown in an interview after the Nobel announcement. “I have had other professors, but he taught me just about everything as to how to do research.”Dr. Negishi moved to Syracuse University as an assistant professor in 1972 and returned to Purdue in 1979 as a professor. He retired in 2019, having been an author of more than 400 scientific papers.In 2010, Dr. Negishi, who remained a Japanese citizen, received the Order of Culture from Emperor Akihito. He was elected to the National Academy of Sciences in 2014.Survivors include two daughters, four grandchildren and one great-granddaughter. His wife of 58 years, Sumire, died in 2018.“When he got his Nobel Prize, he became nicer,” Dr. Tour said. “He’d take his wallet out of his pocket, and protruding from his wallet was the Nobel Prize medallion.”Dr. Tour said Dr. Negishi would pass the medal around and wouldn’t mind if someone dropped it. “You could see the ding in one side of it,” Dr. Tour said. “And he just laughed about it.”

What would you pay for the invention disclosure forms filed by the creators of CRISPR or cancer immunotherapy?How much will someone be willing to pay for a few pages of quarter-century-old bureaucratic university paperwork that have been turned into a blockchain-encoded piece of digital art?The University of California, Berkeley, hopes quite a bit, and it is about to find out.Berkeley announced on Thursday that it will auction the first of two digital art pieces known as nonfungible tokens, or NFTs, next week. The object being offered is based on a document called an invention and technology disclosure. That’s the form that researchers at Berkeley fill out to alert the university about discoveries that have potential to be turned into lucrative patents.The title of the invention, from 1996, is “Blockade of T-Lymphocyte Down-Regulation Associated with CTLA-4 Signalling.”The university hopes that potential bidders will be attracted to an early description of a revolutionary approach to treating cancer developed by James P. Allison, then a professor at Berkeley. He found a way to turn off the immune system’s aversion to attacking tumors and he showed that it worked in mice.That advance eventually led to the creation of Yervoy, a drug for the treatment of metastatic melanoma, and Dr. Allison, who is now at the MD Anderson Cancer Center at the University of Texas, shared the Nobel Prize in Medicine in 2018.Thus, the Berkeley disclosure form could be thought of as the scientific equivalent of Mickey Mantle’s rookie baseball card — a memento of the beginnings of greatness.“I think of it almost as a history of science artifact,” said Richard K. Lyons, the chief innovation and entrepreneurship officer at Berkeley. “Imagine somebody saying, ‘I want to own the NFTs for the 10 most important scientific discoveries of my lifetime.’”A 24-hour auction of the NFT of Dr. Allison’s invention disclosure will take place as early as June 2 using Foundation, an NFT auction marketplace that uses Ethereum, the cryptocurrency network of choice for NFT collectors.Eighty-five percent of the proceeds will go to Berkeley to finance research, the remainder to Foundation. If the piece is later resold, Berkeley will receive 10 percent of the sale and Foundation 5 percent.Because the making of an NFT requires a lot of computing power, part of the money the university earns from the NFT sale will be used for carbon offsets to compensate for the energy consumed, Berkeley officials said.Dr. Allison, left, receiving the Nobel Prize in 2018 from King Carl Gustaf of Sweden.Pool photo by Pontus LundahlThe second NFT that Berkeley plans to auction in the coming weeks will be the disclosure form describing the CRISPR-Cas9 gene editing invention by Jennifer A. Doudna, a professor of molecular and cell biology at Berkeley. She shared the 2020 Nobel Prize in Chemistry with Emmanuelle Charpentier of the Max Planck Unit for the Science of Pathogens for their work on the technique.NFTs have become trendy collectibles in recent months. A unique code embedded in a digital image or video serves as a record of its authenticity and is stored on a blockchain, the same technology that underlies digital currencies like Bitcoin. NFTs can then be bought and sold, just like baseball cards, and the blockchain ensures they cannot be deleted or counterfeited.A dizzying array of documents, far beyond traditional works of art, have been sold as NFTs. Jack Dorsey, the founder of Twitter, sold an NFT of his first tweet for $2.9 million. Kevin Roose, a New York Times columnist, sold an NFT of his article about NFTs for more than half a million dollars. (The money went to The Times’s Neediest Cases Fund.)The pages of Dr. Allison’s disclosure form, drawn from the Berkeley archives, make for mostly dry reading. There is a July 11, 1995, letter from Carol Mimura, a licensing associate at Berkeley, thanking Dr. Allison for contacting the university’s office of technology licensing and asking him to fill out some forms. Another page includes Berkeley’s patent policy.The documents reflect quaintly archaic technologies used in the mid-1990s — typewriters, fax machines and handwritten notes. “I am scrambling to protect patentable matter before late July,” reads a memo from Dr. Mimura, now the assistant vice chancellor for intellectual property and industry research alliances.A fax from Dr. Allison to Dr. Mimura includes a simple chart with three lines and 21 data points. “Carol — This is the data that has got us excited,” Dr. Allison has scribbled.His research group was experimenting with colon cancer in mice, and blocking CTLA-4 — a protein receptor that acts as an on-off switch for the immune system — “led to the rejection of the tumor in 5/5 mice,” Dr. Allison wrote.A fax from James Allison that is included in the NFT being auctioned by the University of California, Berkeley. “Carol — this is the data that has got us excited.”University of California, BerkeleyUntil now, these forms, filed away, unseen, have had no value, Dr. Allison concedes.“That very first exposure to the world is sort of like, ‘This is the invention disclosure,’” he said. “But once they’ve served that purpose, historically, they get no attention.”The NFT idea was the brainstorm of Michael Alvarez Cohen, director of innovation ecosystem development in Berkeley’s intellectual property office. He said part of the idea came after the publication of “The Code Breaker” by Walter Isaacson, a biography of Dr. Doudna. His friends and relatives told him that they had not known that much of the gene editing technology had originated at Berkeley.“So I was kind of like, Maybe we should post excerpts from the invention disclosure to help promote this,” he said.At the same time, he was following news about blockchain and NFTs.“Then about a month ago, I put the two together,” Mr. Cohen said. Take the invention disclosures about Nobel-winning research like CRISPR, turn them into NFTs, “and drive awareness and also fund research by auctioning the NFTs.”He sat on the idea for a while.“I come up with a lot of ideas,” Mr. Cohen said. “Some of them are bone-headed and everything.”Just over two weeks ago, he started discussing it with his colleagues, and quickly a plan fell into place. In addition to CRISPR, they decided to highlight Dr. Allison’s work.The Allison NFT is more than a simple digital document. “It’s a combination of a lab notebook and digital art,” Mr. Cohen said. A single image includes 10 pages but one can zoom in and read the documents. “I really wanted to preserve the ability to read the history in addition to viewing the beauty of the image,” he said.The designers of the NFT also included subtle nods to the initial resistance to Dr. Allison’s ideas. The pages are all slightly tilted, because “people looked at him askew,” Mr. Cohen said. “There’s a lot of little things like that in the art.”Dr. Lyons was reluctant to predict how much the artwork would fetch at auction. “I’d be surprised if it went for less than $100,000,” he said. “It could go into seven figures. This is a new category, and it’s hard to price anything that is a new category.”

Top U.S. health officials sought to reassure Americans on Sunday that the 10-day pause in the use of Johnson & Johnson’s vaccine showed how well safety monitoring for the Covid-19 vaccines worked, and should not add to the hesitancy to get shots among some Americans.“What we’re going to see, and we’ll probably see it soon, is that people will realize that we take safety very seriously,” said Dr. Anthony S. Fauci, the president’s top medical adviser for the coronavirus, during an interview on the ABC News program, “This Week.”“We’re out there trying to combat the degree of vaccine hesitancy that still is out there,” Dr. Fauci said. “And one of the real reasons why people have hesitancy is concern about the safety of the vaccine.”On Friday, federal officials lifted a pause that had been recommended on April 13 for the use of the Johnson & Johnson vaccine because of a few cases of a rare blood clotting disorder that had occurred mainly among younger women. By Friday, experts had identified 15 cases, including three deaths, stemming from the extremely unusual clotting issue. A warning about the risk for the disorder will be included for the company’s product.Public health experts have raised concerns that the Johnson & Johnson pause was particularly worrisome because many states were relying on the one-dose shot to expand vaccinations into harder-to-reach rural areas, and for those who were homebound, homeless and on college campuses. Some officials also worried that the pause would dampen vaccine rates that are already falling in the country.On NBC’s program “Meet the Press,” Dr. Francis Collins, director of the National Institutes of Health, compared the risk of a blood clot from the vaccine — less than 1 in 500,000 — to the danger of aspirin causing significant bleeding in the intestines among people who regularly take aspirin.“We’re talking about something about a thousand times less likely to happen,” Dr. Collins said. “But we Americans are not that good at this kind of risk calculation.”Many states have already announced that they would resume use of the Johnson & Johnson vaccine. Nearly 8 million people had received it before the pause, and about 10 million doses were sitting on shelves around the country waiting to be dispensed.Overall, more than 50 percent of adult Americans have received at least one shot among the three vaccines available, Dr. Fauci said.Both Dr. Fauci and Dr. Collins said it was crucial for a high percentage of Americans to be vaccinated to end the pandemic. “The more people you get vaccinated, the more people you protect,” Dr. Fauci said. “When you get a critical number of people vaccinated, you really have a blanket of protection over the entire community.”Dr. Collins said scientists did not know the exact percentage of people with immunity, either from the vaccine or from antibodies generated from surviving a bout with the virus, that would be needed to reach herd immunity, especially as the coronavirus mutates into new variants that can be more infectious.“But it’s up there around 70, 85 percent,” he said. “And we’re not there yet.”He said that being fully vaccinated was freeing.“My wife and I were able to invite another couple to come to our house to dinner and take off our masks because they were immunized as well and have a normal conversation and hug each other at the end of the evening,” Dr. Collins said. “That was so liberating. If you’re not vaccinated, you’re missing out on that chance to lift that blanket of fear that’s been there.”Asked about calls for lessening restrictions for mask-wearing outdoors, Dr. Fauci said the Centers for Disease Control and Prevention could soon revise its recommendations. “I think it’s pretty common sense now that outdoor risk is really, really quite low,” Dr. Fauci said. “I mean, if you are a vaccinated person, wearing a mask outdoors, obviously, the risk is minuscule.”

Without hospitals or medical specialists in space, NASA and other space agencies have always been concerned about astronauts falling sick during a mission. To minimize the chances of that, they typically spend the two weeks before launch in quarantine.A Covid-19 superspreader event at the space station would disrupt operations.The interior of the space station has a volume equivalent to a Boeing 747 jetliner, so there would be space for infected crew members to isolate themselves. But space station managers certainly would not want to worry about the virus spreading in the station’s perpetually filtered and recycled air.During a news conference last week, Shane Kimbrough, the NASA astronaut who is the commander of Crew-2, said all four astronauts had received Covid vaccinations. “I guess it went fine,” he said. “We all have a little bit different reactions, just like most people do. So we’re no different in that regard. But we’re thankful that we have the vaccines.”The three astronauts who launched in a Soyuz rocket to the station earlier this month — Oleg Novitskiy and Pyotr Dubrov of the Russian space agency and Mark Vande Hei of NASA — were also vaccinated.The four astronauts of the Crew-1 mission are not, because no vaccines were available when they launched last November. When they return to Earth, every human not on the planet will be vaccinated against Covid-19.