The world's largest vaccine maker is ramping up production of AstraZeneca Plc's Covid-19 shot, aiming to have 100 million doses ready by December for an inoculation drive that could begin across India that same month. From a report: If final-stage trial data show AstraZeneca's candidate gives effective protection from the virus, the Serum Institute of India -- which is partnered to produce at least one billion doses -- may get emergency authorization from New Delhi by December, said Adar Poonawalla, chief executive officer of the family-owned firm based in the western city of Pune. That initial amount will go to India, Poonawalla said in an interview on Thursday. Full approval early next year will allow distribution on a 50-50 basis with the South Asian nation and Covax, the World Health Organization-backed body that's purchasing shots for poor nations. Serum, which has tied up with five developers, has so far made 40 million doses of AstraZeneca's vaccine in the past two months and aims to start manufacturing Novavax's contender soon.

Microsoft said Friday it has detected at least seven attacks on companies working to develop a COVID-19 vaccine or treatments. From a report: The company said attacks by three nation-state actors -- two from North Korea and one from Russia -- have targeted companies in Canada, France, India, South Korea and the United States. "Two global issues will help shape people's memories of this time in history -- COVID-19 and the increased use of the internet by malign actors to disrupt society," Microsoft deputy general counsel Tom Burt said in a blog post. "It's disturbing that these challenges have now merged as cyberattacks are being used to disrupt health care organizations fighting the pandemic." Attackers have used a range of approaches including phishing schemes and brute force to get needed passwords, with one group tied to North Korea posing as the World Health Organization in its spear-phishing effort. Microsoft said its built-in security protections stopped a majority of the attacks. "We've notified all organizations targeted, and where attacks have been successful, we've offered help," Burt said.

sciencehabit writes: Two years ago, a global dust storm veiled Mars. But although the storm took a toll, killing off NASA's Opportunity rover, it also revealed that such storms play an important role in how the once-wet planet loses its water. In 2014, looking back at data from 2007, scientists noticed that the fluorescent fog of hydrogen in the martian upper atmosphere faded as the southern hemisphere's summer ended and a previous global dust storm subsided. The only plausible source for that hydrogen was water. Subsequent observations have indicated that water, buoyed by storms, can reach much higher in the atmosphere than previously thought -- all the way to the ionosphere, a new paper reports. This allows charged particles to directly break the water apart, and it is likely the primary method of water loss on the planet today.

An anonymous reader quotes a report from Phys.Org : Even if humanity stopped emitting greenhouse gases tomorrow, Earth will warm for centuries to come and oceans will rise by meters, according to a controversial modeling study published Thursday. Natural drivers of global warming -- more heat-trapping clouds, thawing permafrost, and shrinking sea ice -- already set in motion by carbon pollution will take on their own momentum, researchers from Norway reported in the Nature journal Scientific Reports. Using a stripped-down climate model, [lead author Jorgen Randers, a professor emeritus of climate strategy at the BI Norwegian Business School] and colleague Ulrich Goluke projected changes out to the year 2500 under two scenarios: the instant cessation of emissions, and the gradual reduction of planet warming gases to zero by 2100.

In an imaginary world where carbon pollution stops with a flip of the switch, the planet warms over the next 50 years to about 2.3 degrees Celsius above pre-industrial levels -- roughly half-a-degree above the target set in the 2015 Paris Agreement -- and cools slightly after that. Earth's surface today is 1.2C hotter than it was in the mid-19th century, when temperatures began to rise. But starting in 2150, the model has the planet beginning to gradually warm again, with average temperatures climbing another degree over the following 350 years, and sea levels going up by at least three meters. Under the second scenario, Earth heats up to levels that would tear at the fabric of civilization far more quickly, but ends up at roughly the same point by 2500.

The core finding -- contested by leading climate scientists -- is that several thresholds, or "tipping points", in Earth's climate system have already been crossed, triggering a self-perpetuating process of warming, as has happened millions of years in the past. One of these drivers is the rapid retreat of sea ice in the Arctic. [...] Another source is the thawing of permafrost, which holds twice as much carbon as there is in the atmosphere. The third is increasing amounts of water vapor, which also has a warming effect. Reactions from half-a-dozen leading climate scientists to the study -- which the authors acknowledge is schematic -- varied sharply, with some saying the findings merit follow-up research, and others rejecting it out of hand. There is a way to stop the melting process, but it involves sucking CO2 out of the atmosphere and storing it underground, which isn't yet possible at the scale required. The authors also suggest making Earth's surface brighter and planting billions of trees to slow or halt the planet warming gases.

Temperature and symptom-based screening programs don't help catch coronavirus cases, the US Centers for Disease Control and Prevention said in a new report that took a closer look at the programs used at US airports until mid-September. CNN reports: The CDC said this was a resource-intensive program that had a low case detection rate. Between January 17 and September 13, the CDC screened more than 766,000 travelers. Nearly 300 met the criteria for public health assessment, 35 were tested for the coronavirus, and nine tested positive. That means the program identified about one case per 85,000 travelers screened, the CDC reported Thursday in the agency's weekly report. This style of screening doesn't seem to work for a few reasons. Covid-19 has a wide range of nonspecific symptoms common to other infections, there are a high number of asymptomatic cases, travelers may deny symptoms or take steps to avoid detection and passenger data was limited.

The CDC also only shared contact information with local health departments for 68% of the passengers it screened. There were data collection problems, the report said, and some states opted out of receiving the information. The CDC ended the program September 14. Instead, the CDC has concentrated on communicating more with travelers to promote recommended preventive measures. The agency has also enhanced the public health response capacity at ports of entry. The CDC said travelers and their local communities would be better protected if there was "more efficient" collection of contact information for international air passengers before they arrive and real-time data that could be sent to US health departments. Pre-departure testing within 72 hours before the trip and testing upon arrival would help, as would rules that would encourage a traveler to self-isolate for a certain period.

schwit1 shares a report from Phys.Org: Forget glue, screws, heat or other traditional bonding methods. A Cornell University-led collaboration has developed a 3-D printing technique that creates cellular metallic materials by smashing together powder particles at supersonic speed. This form of technology, known as "cold spray," results in mechanically robust, porous structures that are 40% stronger than similar materials made with conventional manufacturing processes. The structures' small size and porosity make them particularly well-suited for building biomedical components, like replacement joints.

The team's paper, "Solid-State Additive Manufacturing of Porous Ti-6Al-4V by Supersonic Impact," published Nov. 9 in Applied Materials Today. "If we make implants with these kind of porous structures, and we insert them in the body, the bone can grow inside these pores and make a biological fixation," Moridi said. "This helps reduce the likelihood of the implant loosening. And this is a big deal. There are lots of revision surgeries that patients have to go through to remove the implant just because it's loose and it causes a lot of pain." Moridi added: "We only focused on titanium alloys and biomedical applications, but the applicability of this process could be beyond that. Essentially, any metallic material that can endure plastic deformation could benefit from this process. And it opens up a lot of opportunities for larger-scale industrial applications, like construction, transportation and energy."

Thelasko shares a report from the BBC: Early results from trials of a Covid vaccine developed in Russia suggest it could be 92% effective. The data is based on 20 cases of Covid-19 from 16,000 volunteers given the Sputnik V vaccine or a dummy injection. While some scientists welcomed the news, others said the data had been rushed out too early. The Sputnik V vaccine, developed at the National Research Centre for Epidemiology and Microbiology in Moscow, is currently going through phase III clinical trials in Belarus, UAE, Venezuela and India. So far there are no safety issues, with Russian researchers saying there were "no unexpected adverse events" 21 days after volunteers received their first of two injections.

The Russian researchers say their data will be published "in one of the leading international peer-reviewed medical journals." If it's positive, it means there will almost certainly be more than one way of protecting people against the virus. The Pfizer vaccine injects part of the genetic code of the virus into the body to train the immune system. The other two use a harmless virus that has been genetically modified to resemble the coronavirus. Two doses are also required, but one advantage of Sputnik is that it doesn't need to be stored at very low temperatures, around -80C, unlike Pfizer's.

Ticketmaster is planning to check the coronavirus vaccination status of concert-goers prior to shows once a treatment is approved. The New York Post reports: The ticketing giant plans to have customers use their cellphones to verify their inoculation or whether they've tested negative for the virus within a 24- to 72-hour window, according to the exclusive report. The plan, which is still being ironed out, will utilize three separate components, including the California-based company's digital ticketing app, third-party health information firms like CLEAR Health Pass and testing/vaccination distributors like Labcorp or CVS Minute Clinic.

Ticketmaster will reportedly not store or access medical records under the plan. If approved, fans would need to verify that they've either already been vaccinated or have tested negative as recently as 24 hours prior to the show. Concert-goers would then instruct a lab to send over test results to companies like CLEAR Health Pass or IBM's Digital Health Pass, which would verify the fan's status to Ticketmaster. Anyone who tests positive or doesn't get screened won't be granted access to the event venue, Billboard reported. The digital ticketing app will also eliminate the need for paper tickets and can be prohibited from being resold, according to the report. Further reading: Billboard

McDonald has announced plans to introduce its own plant-based burger option to the menu in select markets as soon as next year. From a report: The company made its plans public this week at an investor meeting. The McPlant -- the McPlant! -- uses a fake-meat amalgamation of McDonald's own creation, rather than partnering with an existing plant-based company like Impossible Foods as other chains have. (Beyond Meat and McDonalds co-created the plant-based patty .) "McPlant is crafted exclusively for McDonald's, by McDonald's," McDonald's international president Ian Borden said at this week's meeting. The reveal is a pretty drastic reversal of McDonald's public-facing strategy around plant-based options. If Borden's initial announcement is to be believed, the company doesn't just see it as a single menu option -- rather, McDonald's hopes the McPlant will prove successful enough to extend to a full plant-based menu.

A British firm has won a European Space Agency contract to develop the technology to turn moon dust and rocks into oxygen, leaving behind aluminium, iron and other metal powders for lunar construction workers to build with. The Guardian reports: If the process can be made to work well enough, it will pave the way for extraction facilities on the moon that make oxygen and valuable materials on the surface, rather than having to haul them into space at enormous cost. Analyses of rocks brought back from the moon reveal that oxygen makes up about 45% of the material by weight. The remainder is largely iron, aluminium and silicon. In work published this year, scientists at Metalysis and the University of Glasgow found they could extract 96% of the oxygen from simulated lunar soil, leaving useful metal alloy powders behind.

The Esa contract will fund Metalysis for nine months to perfect an electrochemical process that releases oxygen from lunar dust and rocks by sending an electrical current through the material. The process is already used on Earth, but the oxygen is released as an unwanted byproduct of mineral extraction. To make it work for lunar explorers, the oxygen must be captured and stored. Under the contract, the firm will try to boost the yield and purity of oxygen and metals from the rock while reducing the amount of energy the process consumes. If the technology looks promising, the next step will be to demonstrate oxygen extraction on the moon. The oxygen released from the lunar surface can be combined with other gases to produce breathable air, but it is also a vital component of rocket propellant that could be manufactured on the moon and used to refuel spacecraft bound for deep space.

An anonymous reader shares an excerpt from Wired: On Monday morning, when representatives from the drug company Pfizer said that its Covid-19 vaccine appears to be more than 90 percent effective, stocks soared, White House officials rushed to (falsely) claim credit, and sighs of relief went up all around the internet. [...] The arrival of an effective vaccine to fight SARS-CoV-2 less than a year after the novel coronavirus emerged would smash every record ever set by vaccine makers. "Historic isn't even the right word," says Larry Corey of the Vaccine and Infectious Disease Division at the Fred Hutchinson Cancer Center. A renowned virologist, Corey has spent the last three decades leading the search for a vaccine against the virus that causes AIDS. He's never seen an inoculation developed for a new bug in under five years, let alone one. "It's never happened before, never, not even close," he says. "It's just an amazing accomplishment of science."

And perhaps even more monumental is the kind of vaccine that Pfizer and BioNTech are bringing across the finish line. The active ingredient inside their shot is mRNA -- mobile strings of genetic code that contain the blueprints for proteins. Cells use mRNA to get those specs out of hard DNA storage and into their protein-making factories. The mRNA inside Pfizer and BioNTech's vaccine directs any cells it reaches to run a coronavirus spike-building program. The viral proteins these cells produce can't infect any other cells, but they are foreign enough to trip the body's defense systems. They also look enough like the real virus to train the immune system to recognize SARS-CoV-2, should its owner encounter the infectious virus in the future. Up until now, this technology has never been approved for use in people. A successful mRNA vaccine won't just be a triumph over the new coronavirus, it'll be a huge leap forward for the science of vaccine making.

[I]n the last decade, the field has started to move away from this see-what-sticks approach toward something pharma folks call "rational drug design." It involves understanding the structure and function of the target -- like say, the spiky protein SARS-CoV-2 uses to get into human cells -- and building molecules that can either bind to that target directly, or produce other molecules that can. Genetic vaccines represent an important step in this scientific evolution. Engineers can now design strands of mRNA on computers, guided by algorithms that predict which combination of genetic letters will yield a viral protein with just the right shape to prod the human body into producing protective antibodies. In the last few years, it's gotten much easier and cheaper to make mRNA and DNA at scale, which means that as soon as scientists have access to a new pathogen's genome, they can start whipping up hundreds or thousands of mRNA snippets to test -- each one a potential vaccine. The Chinese government released the genetic sequence of SARS-CoV-2 in mid-January. By the end of February, BioNTech had identified 20 vaccine candidates, of which four were then selected for human trials in Germany. [...] Genetic vaccines might be proving they can work -- but it's still not definitive, and they may not yet work for everyone. That's why experts say it's so crucial to continue supporting ongoing trials for the more than 60 other vaccine candidates still in various stages of human testing. What older technologies lack in terms of speed, they make up for in durability.

A cryptographic master tool called indistinguishability obfuscation has for years seemed too good to be true. Three researchers have figured out that it can work. Erica Klarreich, reporting for Quanta Magazine: In 2018, Aayush Jain, a graduate student at the University of California, Los Angeles, traveled to Japan to give a talk about a powerful cryptographic tool he and his colleagues were developing. As he detailed the team's approach to indistinguishability obfuscation (iO for short), one audience member raised his hand in bewilderment. "But I thought iO doesn't exist?" he said. At the time, such skepticism was widespread. Indistinguishability obfuscation, if it could be built, would be able to hide not just collections of data but the inner workings of a computer program itself, creating a sort of cryptographic master tool from which nearly every other cryptographic protocol could be built. It is "one cryptographic primitive to rule them all," said Boaz Barak of Harvard University. But to many computer scientists, this very power made iO seem too good to be true. Computer scientists set forth candidate versions of iO starting in 2013. But the intense excitement these constructions generated gradually fizzled out, as other researchers figured out how to break their security. As the attacks piled up, "you could see a lot of negative vibes," said Yuval Ishai of the Technion in Haifa, Israel. Researchers wondered, he said, "Who will win: the makers or the breakers?" "There were the people who were the zealots, and they believed in [iO] and kept working on it," said Shafi Goldwasser, director of the Simons Institute for the Theory of Computing at the University of California, Berkeley. But as the years went by, she said, "there was less and less of those people."

Now, Jain -- together with Huijia Lin of the University of Washington and Amit Sahai, Jain's adviser at UCLA -- has planted a flag for the makers. In a paper posted online on August 18, the three researchers show for the first time how to build indistinguishability obfuscation using only "standard" security assumptions. All cryptographic protocols rest on assumptions -- some, such as the famous RSA algorithm, depend on the widely held belief that standard computers will never be able to quickly factor the product of two large prime numbers. A cryptographic protocol is only as secure as its assumptions, and previous attempts at iO were built on untested and ultimately shaky foundations. The new protocol, by contrast, depends on security assumptions that have been widely used and studied in the past. "Barring a really surprising development, these assumptions will stand," Ishai said. While the protocol is far from ready to be deployed in real-world applications, from a theoretical standpoint it provides an instant way to build an array of cryptographic tools that were previously out of reach. For instance, it enables the creation of "deniable" encryption, in which you can plausibly convince an attacker that you sent an entirely different message from the one you really sent, and "functional" encryption, in which you can give chosen users different levels of access to perform computations using your data. The new result should definitively silence the iO skeptics, Ishai said. "Now there will no longer be any doubts about the existence of indistinguishability obfuscation," he said. "It seems like a happy end."

An anonymous reader writes: Glaciers in China's bleak Qilian mountains are disappearing at a shocking rate as global warming brings unpredictable change and raises the prospect of crippling, long-term water shortages, scientists say. The largest glacier in the 800-kilometer (500-mile) mountain chain on the arid northeastern edge of the Tibetan plateau has retreated about 450 meters since the 1950s, when researchers set up China's first monitoring station to study it. The 20-square kilometer glacier, known as Laohugou No. 12, is criss-crossed by rivulets of water down its craggy, grit-blown surface. It has shrunk by about 7% since measurements began, with melting accelerating in recent years, scientists say. Equally alarming is the loss of thickness, with about 13 meters (42 feet) of ice disappearing as temperatures have risen, said Qin Xiang, the director at the monitoring station. "The speed that this glacier has been shrinking is really shocking," Qin told Reuters on a recent visit to the spartan station in a frozen, treeless world, where he and a small team of researchers track the changes. The Tibetan plateau is known as the world's Third Pole for the amount of ice long locked in the high-altitude wilderness. But since the 1950s, average temperatures in the area have risen about 1.5 Celsius, Qin said, and with no sign of an end to warming, the outlook is grim for the 2,684 glaciers in the Qilian range. Across the mountains, glacier retreat was 50% faster in 1990-2010 than it was from 1956 to 1990, data from the China Academy of Sciences shows.

The reopening of restaurants, gyms and hotels carries the highest risk of spreading Covid-19, according to a study that used mobile phone data from 98 million people to model the risks of infection at different locations. From a report: Researchers at Stanford University and Northwestern University used data collected between March and May in cities across the U.S. to map the movement of people. They looked at where they went, how long they stayed, how many others were there and what neighborhoods they were visiting from. They then combined that information with data on the number of cases and how the virus spreads to create infection models. In Chicago, for instance, the study's model predicted that if restaurants were reopened at full capacity, they would generate almost 600,000 new infections, three times as many as with other categories. The study, published Tuesday in the journal Nature, also found that about 10% of the locations examined accounted for 85% of predicted infections. This type of very granular data "shows us where there is vulnerability," said Eric Topol, of the Scripps Research Translational Institute, which wasn't involved in the study. "Then what you need to do is concentrate on the areas that light up."

fahrbot-bot shares a report from CNN: A team of physicists at a university in the Netherlands have 3D-printed a microscopic version of the USS Voyager, an Intrepid-class starship from Star Trek. The miniature Voyager, which measures 15 micrometers (0.015 millimeters) long, is part of a project researchers at Leiden University conducted to understand how shape affects the motion and interactions of microswimmers.

Microswimmers are small particles that can move through liquid on their own by interacting with their environment through chemical reactions. The platinum coating on the microswimmers reacts to a hydrogen peroxide solution they are placed in, and that propels them through the liquid. "By studying synthetic microswimmers, we would like to understand biological microswimmers," Samia Ouhajji, one of the study's authors, told CNN. "This understanding could aid in developing new drug delivery vehicles; for example, microrobots that swim autonomously and deliver drugs at the desired location in the human body." In their project, the physicists also printed shapes like boats, trimers and helices, with each object's shape affecting their swimming behaviors.

Greenhouse gas emissions from U.S. power plants, manufacturing sites and other large facilities declined nearly 5% from 2018 to 2019, according to data released Monday. Bloomberg reports: The drop is consistent with a decade-long downward trend in greenhouse gas releases from large stationary sources, partly propelled by the power sector's ongoing shift away from coal to renewable sources and cleaner-burning natural gas. The new data reflect emissions from nearly 8,000 large, stationary facilities -- including cement plants, steel mills, oil refineries and landfills. The numbers do not cover small stationary sources that emit fewer than 25,000 metric tons of carbon dioxide equivalent annually. Nor do they cover the transportation sector, now the single biggest source of greenhouse gas emissions in the U.S.

Large facilities in the reporting program emitted 2.85 billion metric tons of carbon dioxide or its equivalent in 2019, down from 2.99 billion metric tons in 2018. Overall U.S. greenhouse gas emissions have been on a downward trend since 2005, a commonly used baseline. However, they increased 2.9% in 2018 over 2017 levels, after three years of annual declines, according to a separate EPA inventory, the last year for which data is available.

According to USA Today, McDonald's has developed a new plant-based platform dubbed McPlant that will debut in markets around the world early next year. From the report: "McPlant is crafted exclusively for McDonald's, by McDonald's," Ian Borden, McDonald's international president, said at the investor meeting. "In the future, McPlant could extend across a line of plant-based products including burgers, chicken substitutes and breakfast sandwiches." The plant-based and chicken sandwich announcements were part of the company's new growth strategy called "Accelerating the Arches." The strategy includes a commitment to the core menu.

"There are other plant-based burgers out there, but the McPlant delivers our iconic taste in a sink-your-teeth-in (and wipe-your-mouth) kind of sandwich," McDonald's said in a blog post Monday. "It's made with a juicy, plant-based patty and served on a warm, sesame seed bun with all the classic toppings." Borden said some markets will test the burger next year. Whether or not the vegan-friendly burger will arrive in the U.S. and a potential timeline was not immediately known. "We are excited about the opportunity because we believe we have a proven, delicious-tasting product," Borden said. "When customers are ready for it, we will be ready for them." Beyond Meat, a pioneer of plant-based meat substitutes, said it co-created the plant-based patty that will be part of the McPlant platform with McDonald's.

An anonymous reader shares a report: Earthlings are lucky to live near a relatively stable Sun, which has enabled life on our planet to emerge and thrive over the past four billion years. While many worlds in our galaxy might contain the right ingredients to support life, though, a lot of them could be stuck with a more volatile star that prevents them from becoming -- or remaining -- habitable. To get a better grip on which types of star systems might be most likely to host aliens, a pair of scientists at New York University Abu Dhabi (NYUAD) Center for Space Science have observed space weather around nearly 500 stars, according to a study published on Sunday in the journal Monthly Notices of Royal Astronomical Society: Letters. The results suggest that planets subjected to occasional but intense flares are probably more hospitable to life than worlds that receive a constant flux of radiation and low-energy flares, which blows their protective atmospheres away. Planetary habitability "is one of the most important concepts in exoplanet science" and "is defined as the zone around a star in which a planet is able to sustain liquid water on its surface," said research scientist Dimitra Atri and graduate student Shane Carberry Mogan, both at NYUAD, in the study. "While this approach is useful to identify potentially hospitable planets around stars, it fails to take into account the damaging aspect of stellar activity on such planets," the pair added. "The main goal of this paper is to understand how stellar luminosity and flares can lead to atmospheric escape on [habitable zone] planets on long time-scales and how these losses impact planetary habitability."

NASA administrator Jim Bridenstine says he plans to leave his position at the space agency under the new Joe Biden administration, even if he's asked to stay, according to an interview he did with Aviation Week. Bridenstine said the decision would be to ensure NASA has the right leader who connects with the new president. From a report: "What you need is somebody who has a close relationship with the president of the United States," Bridenstine told Aviation Week. "You need somebody who is trusted by the administration... including the OMB [Office of Management and Budget], the National Space Council and the National Security Council, and I think that I would not be the right person for that in a new administration." President Trump nominated Bridenstine, then a Republican representative from Oklahoma, to lead NASA in 2017. Bridenstine's confirmation became a contentious one, with many lawmakers decrying the idea of a politician running a scientific agency like NASA. "NASA is one of the last refuges from partisan politics," former Sen. Bill Nelson (D-FL) said during Bridenstine's confirmation hearing in November 2017. "NASA needs a leader who will unite us, not divide us. Respectfully, Congressman Bridenstine, I don't think you're that leader." Eventually, the Senate did narrowly confirm him in April 2018, with lawmakers voting along party lines.

A single shot given every two months has proved to be more effective than a daily pill at preventing H.I.V. in women, researchers reported on Monday, an advance that medical experts hailed as groundbreaking in the fight against the deadly virus that causes AIDS. From a report: The finding that the long-acting drug would prevent H.I.V. in six doses taken over a year instead of the 365 required for the prevention pill currently on the market was so convincing the researchers decided to end their clinical trial of the drug early. "It's a game changer for women," said Dr. Sigal Yawetz, an expert on women with H.I.V. at Brigham and Women's Hospital in Boston who was not involved in the trial. Women and girls accounted for about half of all new H.I.V. infections in 2019, according to Unaids, a United Nations organization that leads the global fight against H.I.V. and AIDS. In sub-Saharan Africa, five in six new infections among adolescents ages 15 to 19 are among girls. "If we're going to get to the end of the epidemic, we have to do something to stem the tide of infection in those women," said Dr. Kimberly Smith, head of research and development at ViiV Healthcare, which manufactures the injection. "That is why this study is so important. It gives a new, incredibly effective option for women." Women have had only one approved option for pre-exposure prophylaxis, or PrEP, a course of drugs taken to prevent contracting H.I.V.: the daily pill Truvada, made by Gilead Sciences. (A second pill also made by Gilead, called Descovy, was approved in October 2019, but only for men and transgender women.)