Humans are creating or exacerbating the environmental conditions that could lead to further pandemics, new University of Sydney research finds.
Modelling from the Sydney School of Veterinary Science suggests pressure on ecosystems, climate change and economic development are key factors associated with the diversification of pathogens (disease-causing agents, like viruses and bacteria). This has potential to lead to disease outbreaks.
The research, by Dr Balbir B Singh, Professor Michael Ward, and Associate Professor Navneet Dhand, is published in the international journal, Transboundary and Emerging Diseases.
They found a greater diversity of zoonotic diseases (diseases transmitted between animals and humans) in higher income countries with larger land areas, more dense human populations, and greater forest coverage.
The study also confirms increasing population growth and density are major drivers in the emergence of zoonotic diseases. The global human population has increased from about 1.6 billion in 1900 to about 7.8 billion today, putting pressure on ecosystems.
Associate Professor Dhand said: “As the human population increases, so does the demand for housing. To meet this demand, humans are encroaching on wild habitats. This increases interactions between wildlife, domestic animals and human beings which increases the potential for bugs to jump from animals to humans.”
“To date, such disease models have been limited, and we continue to be frustrated in understanding why diseases continue to emerge,” said Professor Ward, an infectious diseases expert.

Working with fruit flies, scientists at Johns Hopkins Medicine say they have identified a new molecular pathway that helps steer moving cells in specific directions. The set of interconnected proteins and enzymes in the pathway act as steering and rudder components that drive cells toward an “intended” rather than random destination, they say.
In a report on the work, published March 2 in Cell Reports, these same molecular pathways, say the scientists, may drive cancer cells to metastasize or travel to distant areas of the body and may also be important for understanding how cells assemble and migrate in an embryo to form organs and other structures.
The team of scientists was led by Deborah Andrew, Ph.D., professor of cell biology and associate director for faculty development for the Institute for Basic Biomedical Sciences at the Johns Hopkins University School of Medicine.
Andrew and her colleagues began this research while studying a gene called Tre1 and its role in the development of salivary glands in fruit flies. The tools to study the effects of turning the gene on and off weren’t ideal, she says. So, two of the team members, Caitlin Hanlon, Ph.D., of Quinnipiac University and JiHoon Kim, Ph.D., of Johns Hopkins, generated fruit flies that lack the protein-coding portion of the Tre1 gene. The pair also put a fluorescent tag on the Tre1 protein to learn where it localized during key steps in development.
In experiments with fruit fly embryos carrying an intact Tre1 gene, cells that produce future generations of the organism, called germ cells, migrate correctly to the sex organ, known as the gonad.
“Without the Tre1 gene, however, most of the germ cells failed to meet up with other nongerm cells, or somatic cells, of the gonad,” says Andrew. “Correct navigation of germ cells is important to ensure that future generations of the organism will happen.”
This is not the first time that scientists noted Tre1’s importance in germ cell navigation. Two research teams from Indiana University and the Massachusetts Institute of Technology had previously made the link. However, says Andrew, questions remained about what happens inside germ cells to get cells to the right place once Tre1 activates.

One in four Germans suffers from metabolic syndrome. Several of four diseases of affluence occur at the same time in this ‘deadly quartet’: obesity, high blood pressure, lipid metabolism disorder and diabetes mellitus. Each of these is a risk factor for severe cardiovascular conditions, such as heart attack and stroke. Treatment aims to help patients lose weight and normalise their lipid and carbohydrate metabolism and blood pressure. In addition to exercise, doctors prescribe a low-calorie and healthy diet. Medication is often also required. However, it is not fully clear what effects nutrition has on the microbiome, immune system and health.
A research group led by Dr Sofia Forslund and Professor Dominik N. Müller from the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) and the Experimental and Clinical Research Center (ECRC) has now examined the effect a change of diet has on people with metabolic syndrome. The ECRC is jointly run by the MDC and Charité Universitätsmedizin Berlin. “Switching to a healthy diet has a positive effect on blood pressure,” says Andras Maifeld, summarising the results. “If the diet is preceded by a fast, this effect is intensified.” Maifeld is the first author of the paper, which was recently published in the journal Nature Communications.
Broccoli over roast beef
Dr Andreas Michalsen, Senior Consultant of the Naturopathy Department at Immanuel Hospital Berlin and Endowed Chair of Clinical Naturopathy at the Institute for Social Medicine, Epidemiology and Health Economics at Charité — Universitätsmedizin Berlin, and Professor Gustav J. Dobos, Chair of Naturopathy and Integrative Medicine at the University of Duisburg-Essen, recruited 71 volunteers with metabolic syndrome and raised systolic blood pressure. The researchers divided them into two groups at random.
Both groups followed the DASH (Dietary Approach to Stop Hypertension) diet for three months, which is designed to combat high blood pressure. This Mediterranean-style diet includes lots of fruit and vegetables, wholemeal products, nuts and pulses, fish and lean white meat. One of the two groups did not consume any solid food at all for five days before starting the DASH diet.
On the basis of immunophenotyping, the scientists observed how the immune cells of the volunteers changed when they altered their diet. “The innate immune system remains stable during the fast, whereas the adaptive immune system shuts down,” explains Maifeld. During this process, the number of proinflammatory T cells drops, while regulatory T cells multiply.
A Mediterranean diet is good, but to also fast is better
The researchers used stool samples to examine the effects of the fast on the gut microbiome. Gut bacteria work in close contact with the immune system. Some strains of bacteria metabolise dietary fibre into anti-inflammatory short-chain fatty acids that benefit the immune system. The composition of the gut bacteria ecosystem changes drastically during fasting. Health-promoting bacteria that help to reduce blood pressure multiply. Some of these changes remain even after resumption of food intake. The following is particularly noteworthy: “Body mass index, blood pressure and the need for antihypertensive medication remained lower in the long term among volunteers who started the healthy diet with a five-day fast,” explains Dominik Müller. Blood pressure normally shoots back up again when even one antihypertensive tablet is forgotten.
Blood pressure remains lower in the long term — even three months after fasting
Together with scientists from the Helmholtz Centre for Infection Research and McGill University, Montreal, Canada, Forslund’s working group conducted a statistical evaluation of these results using artificial intelligence to ensure that this positive effect was actually attributable to the fast and not to the medication that the volunteers were taking. They used methods from a previous study in which they had examined the influence of antihypertensive medication on the microbiome. “We were able to isolate the influence of the medication and observe that whether someone responds well to a change of diet or not depends on the individual immune response and the gut microbiome,” says Forslund.
If a high-fibre, low-fat diet fails to deliver results, it is possible that there are insufficient gut bacteria in the gut microbiome that metabolise fibre into protective fatty acids. “Those who have this problem often feel that it is not worth the effort and go back to their old habits,” explains the scientist. It is therefore a good idea to combine a diet with a fast. “Fasting acts as a catalyst for protective microorganisms in the gut. Health clearly improves very quickly and patients can cut back on their medication or even often stop taking tablets altogether.” This could motivate them to stick to a healthy lifestyle in the long term.

The latest gene editing technology, prime editing, expands the “genetic toolbox” for more precisely creating disease models and correcting genetic problems, scientists say.
In only the second published study of prime editing’s use in a mouse model, Medical College of Georgia scientists report prime editing and traditional CRISPR both successfully shut down a gene involved in the differentiation of smooth muscle cells, which help give strength and movement to organs and blood vessels.
However, prime editing snips only a single strand of the double-stranded DNA. CRISPR makes double-strand cuts, which can be lethal to cells, and produces unintended edits at both the work site as well as randomly across the genome, says Dr. Joseph Miano, genome editor, molecular biologist and J. Harold Harrison, MD, Distinguished University Chair in Vascular Biology at the MCG Vascular Biology Center.
“It’s actually less complicated and more precise than traditional CRISPR,” Miano says of prime editing, which literally has fewer components than the game-changing gene-editing tool CRISPR.
Miano was among the first wave of scientists to use CRISPR to alter the mouse genome in 2013. Two scientists were awarded the 2020 Nobel Prize in Chemistry for the now 9-year-old CRISPR, which enabled rapid development of animal models, as well as the potential to cure genetic diseases like sickle cell, and potentially reduce the destruction caused by diseases like cancer, in which environmental and genetic factors are both at play.
Prime editing is the latest gene-editing technology, and the MCG scientists report in the journal Genome Biology that they were able to use it to remove expression of a gene in smooth muscle tissue, illustrating prime editing’s ability to create cell-specific knockout mice without extensive breeding efforts that may not result in an exact model, says Dr. Xiaochun Long, molecular biologist in the Vascular Biology Center. Miano and Long are corresponding authors of the new study.

Artificial Intelligence is now capable of generating novel, functionally active proteins, thanks to recently published work by researchers from Chalmers University of Technology, Sweden.
“What we are now able to demonstrate offers fantastic potential for a number of future applications, such as faster and more cost-efficient development of protein-based drugs,” says Aleksej Zelezniak, Associate Professor at the Department of Biology and Biological Engineering at Chalmers.
Proteins are large, complex molecules that play a crucial role in all living cells, building, modifying, and breaking down other molecules naturally inside our cells. They are also widely used in industrial processes and products, and in our daily lives.
Protein-based drugs are very common — the diabetes drug insulin is one of the most prescribed. Some of the most expensive and effective cancer medicines are also protein-based, as well as the antibody formulas currently being used to treat COVID-19.
From computer design to working proteins in just a few weeks
Current methods used for protein engineering rely on introducing random mutations to protein sequences. However, with each additional random mutation introduced, the protein activity declines.

SharecloseShare pageCopy linkAbout sharingimage copyrightGetty ImagesRoughly half of people in the UK now have antibodies against Covid, either through infection or vaccination, tests conducted by the Office for National Statistics (ONS) show. Most of this will be through vaccination – with 30 million people having received at least one dose.Antibodies are proteins in the blood which recognise specific infections and fight them off.Among the oldest who are most at risk, levels are even higher.But there has been a small decline in detectable antibodies in that group since the peak of infections in January.The ONS speculates this might be people who received the vaccine earliest having had their first dose but not their second – but they stress this is not evidence that these people have less immunity.Yes/no resultOnce someone has had an infection, antibodies help your body to be ready if it encounters it again. Vaccines provide a safe way to develop antibodies without risking getting ill. The tests used in the ONS study give a yes/no result based on whether the amount of antibodies in your blood cross a certain threshold.But people can be protected by lower levels of antibodies. And there are other element of your immune system like T-cells which are not being measured here. There is some evidence to suggest protective T-cells might be detectable for longer than antibodies.It’s possible some of the decline is from infections in the first wave, as we know antibodies from infection drop off over time. The study is conducted by taking blood from a representative sample of people around the UK to estimate what proportion of the whole population has antibodies. By 14 March, an estimated 55% of people in England had antibodies, 51% in Wales, 49% in Northern Ireland and 43% in Scotland. Vast majority retain Covid antibodies six months onCan you catch Covid twice?But among the over-65s, who are most likely to have been vaccinated, roughly 90% had antibodies. The figures mark a rapid rise in people in the population having protection against Covid – up from roughly a third of people testing positive when levels were measured at the start of March.Other data published today shows the number of deaths seen across the UK has remained below what is expected at this time of year, having dipped under average last week. There were 11,666 deaths registered in the week ending 19 March – 8% below the five-year average for this week.

Amid the chatter of travel’s long-awaited rebound one year into the pandemic, many families with children feel largely left out of the conversation.Nearly every summer, Ada Ayala, a teacher, and her husband, Oscar Cesar Pleguezeulos, travel with their children to visit Mr. Cesar Pleguezeulos’s parents in Spain. But this year, even though they will both soon be fully vaccinated in their home state of Florida, they are changing their plans. The reason? There is still no pediatric Covid-19 vaccine available for their kids.The travel industry, buoyed by news of vaccine rollouts, is anticipating a summer rush after a year of devastation. But amid the chatter of travel’s long-awaited rebound, many families with children — who comprise roughly 30 percent of the global travel market — say they are largely being left out of the conversation.In a March survey on Bébé Voyage, an online community for traveling families, 90 percent of respondents said that amid unclear guidelines on Covid-19 testing, they were searching for flexible bookings. The topic also comes up often on Bébé Voyage’s Facebook page, particularly among parents in the United States. “It’s the Americans in the group that are the most nervous traveling with kids,” said the Bébé Voyage chief executive, Marianne Perez de Fransius.Ms. Ayala, 44, is among those nervous parents. “If it wasn’t for the kids, we would definitely be flying this summer,” she said. Ms. Ayala already received her shot as a teacher. Her husband, also 44, will soon receive his shots, too, because Florida recently opened vaccinations to those age 40 and up. But their children, Charlise, 6, and Oscar, 2, will have to wait many more months to be inoculated.“My 2-year-old isn’t going to wear a mask for 10 hours on a flight, and I don’t know if I want to expose him for a 16-hour trip with layovers,” Ms. Ayala said. “I’ll feel more confident when vaccination reaches more people worldwide, or at least in the destinations we want to go.”Nearly one in three adults in the United States have now received at least one dose of the Covid-19 vaccine. But a full pediatric Covid-19 vaccine currently isn’t expected until the end of 2021 at the earliest, and while they wait, parents are struggling to figure out how they, too, can travel safely this summer, and even where their children are welcome as rules on quarantine and testing continue to shift.“This is the elephant in the room right now,” said Cate Caruso, an adviser for Virtuoso, a network of luxury travel agencies, who also owns her own travel planning company, True Places Travel. The potential that a child could become infected with Covid-19 while abroad and not be allowed on a return flight, she said, is a major deterrent for parents. “Anywhere you go outside of the U.S. right now, you’ve got to think about how you’re going to get back in,” she said. “It’s leaving behind a whole bunch of people who are ready to go.”In Ms. Ayala’s case, a compromise has been struck: If and when Spain — which is currently closed to American travelers — opens its borders, Mr. Cesar will travel to Spain with their daughter, Charlise, while Ms. Ayala will remain in Florida with Oscar. “She goes to school and is very good with wearing her mask, cleaning her hands and keeping distance,” Ms. Ayala said of her daughter. “So I think she can be safe. But it’s just not possible with a baby.”But she doesn’t plan to stay home all summer. Whether or not her husband and daughter make it to Spain, Ms. Ayala is planning a family road trip at some point this summer, likely within Florida.After a year of road trips, R.V.s and rental cottages, many Americans are now ready to fly again: Online searches for late-summer flights are up as much as 75 percent, and hotels on both coasts are reporting that they are sold out through October. But families, more than any other travel sector, continue to play it safe.Family travel plans for this summer are more low-key than two years ago, with bookings to Mount Rushmore National Memorial, in the Black Hills of South Dakota, reported to be significantly up.Tannen Maury/EPA, via ShutterstockRovia, a membership-based global travel agency that works with both travelers and travel agents, reports that beach and camping destinations within driving distance are the most popular choices for families this summer. An exception? Disney World, which is seeing an uptick in reservations for summer from families looking to visit while capacity remains limited (and lines, as a result, remain shorter).“The rate of couples traveling by air has increased faster, whereas families are still leaning toward travel by car and R.V. rentals,” said Jeff Gwynn, Rovia’s director of communications.Montoya and Phil Hudson, who showcase their travels as a Black family on their popular blog, The Spring Break Family, are among them. “Most years we go pretty far — Spain, Italy, France, as far as we can go. This year it was about what’s reachable by car,” Ms. Hudson said. She and Mr. Hudson, who both work in the health care industry, are vaccinated, but admit they probably won’t be willing to fly with their two daughters, Leilah, 11, and Layla, 8, for several more months.That’s because they want to wait for herd immunity to help keep their daughters safe. “The goal is to wait until the majority of the population is vaccinated, or has at least had the opportunity to become vaccinated,” Ms. Hudson said.In addition to preferring driving over flying this summer, travel analysts say families with children will also continue to opt for rental homes over hotel rooms.In fact, when it comes to the vacation cottage market, parents are booking faster than anyone else. “Families are the number one group expected to travel in 2021,” said Vered Schwarz, the president and chief operating officer of Guesty, a short-term property management platform which reports that its summer reservations are already 110 percent higher than 2020, with families comprising more than 30 percent of those booking. “For families with unvaccinated children, private rentals are appealing — they are comfortable and they avoid hotels chock-full of crowded common areas,” she said.The question of how to treat unvaccinated children who may be traveling with their parents is also presenting a legal and ethical minefield for American travel operators.The European Union is considering a vaccine passport that will allow free travel within the bloc for those who can show proof of inoculation. In Israel, a green pass has been established for those who have been vaccinated, granting holders not just the ability to cross a border but also check into a hotel or eat inside a restaurant, but children are not exempt — so parents with unvaccinated children must dine outside at restaurants and find babysitters before heading to the gym or a show.But in the United States, such policies are unlikely to take hold, said Chuck Abbott, the general manager of the InterContinental San Diego. “Most hotels would not ask for that information, because it violates the privacy of the guest,” he said. “Even putting vaccinated guests on a different floor than other guests would likely present a legal issue.”Compared with summer 2019, families’ plans for summer 2021 are more low-key: Travelocity reports that bookings to Mount Rushmore and Nashville are significantly up over two years ago; internationally, family bookings to London, Paris and Rome, destinations that were top family sites in 2019, but have still not reopened to U.S. travel, are way down, while Cancún, which is currently open to American travelers without quarantine requirements, is up nearly 50 percent.Some European countries, like Iceland, have begun inching open their borders, but only to passengers who are vaccinated. That means individuals who can present proof of the Covid-19 jab can bypass quarantine when they arrive — unless they are parents traveling with children.“Unvaccinated children would still need to quarantine for five days, and the parents, of course, must stay with the child,” said Eric Newman, who owns the travel blog Iceland With Kids. “Iceland’s brand-new travel regulations are not friendly to families hoping to visit with children.”After a year of virtual schooling and working from home, parents have no desire to quarantine with their kids, said Anthony Berklich, the founder of the travel platform Inspired Citizen. “What these destinations are basically saying is you can come but your children can’t,” he said.Instead, families are opting for warm-weather destinations closer to home.When the Centers for Disease Control and Prevention announced in January that proof of a negative PCR test would be required of all air passengers arriving in the United States, many tropical resorts — including more than a dozen Hyatt properties — began offering not just free on-site testing, but a deeply discounted room in which to quarantine in case that test comes back positive. That move, said Rebecca Alesia, a travel consultant with SmartFlyer, has been a boon for family travel business.“What happens if the morning you’re supposed to come home, you get up and Junior has a surprise positive test?” she said. “A lot of my clients have booked this summer because of this policy.”For parents struggling to decide how and when to return to travel, there is good news on the horizon, said Dr. Shruti Gohil, the medical director of infection prevention at the University of California, Irvine.“The chances of a good pediatric vaccine coming soon are high,” she said, noting that both Pfizer and Moderna are already running pediatric trials on their vaccines. “There is no reason to think that the vaccine will have any untoward effects on children that we haven’t already noted in adults.”In the meantime, she said, parents with children need to continue to be cautious. That doesn’t mean families shouldn’t travel at all, but she recommends choosing to drive rather than fly; to not allow unvaccinated children to play unmasked with children from other households; and to remain vigilant about wearing masks and regularly washing hands while on the road.“We can’t keep saying that you can’t go anywhere,” she said. “At some point we have to have some kind of nuance around this. But this is a game we are all still playing until the virus is gone.”Follow New York Times Travel on Instagram, Twitter and Facebook. And sign up for our weekly Travel Dispatch newsletter to receive expert tips on traveling smarter and inspiration for your next vacation.

The magazine’s Ethicist columnist on balancing health care providers’ privacy against patients’ concerns, creating an equitable vaccine system and more.I was planning to make an appointment with a hygienist working under my dentist and was told by a third party that one of the hygienists had contracted Covid, been treated and was back to work. I am 69, and my nephew died of Covid last May. Four other relatives contracted the virus and recovered. I am nervous about the pandemic.I requested not to be treated by that hygienist and received this email in response: “To protect the privacy of our staff, just as we do for our patients, we cannot confirm or deny if someone has recovered from the coronavirus. This would be a violation of HIPAA. Your request to not be seen by someone who tested Covid-19 positive was not appropriate, as C.D.C. guidelines state that after 14 days of quarantine, individuals are safe to go out in public. In addition, our clinicians wear appropriate P.P.E. for treatment (including N95 masks, face shields, gowns, gloves), and our office has implemented additional infection-control measures. We monitor for symptoms, take temperatures and measure oxygen saturation daily for everyone that comes into our suite. If this policy makes you uncomfortable, our office may not be a good fit for you.”I have a problem with putting the privacy of an employee ahead of the concerns of a patient. I also thought that HIPAA applied only to disclosures by a doctor about their patients. Am I out of line to make this request? Should a doctor or dentist tell patients if a staff member has had the virus so that the patient can make an informed decision about treatment? Jack L. Schwartz, Los AngelesAll employers, including medical employers like your dentist, are entitled to have certain kinds of health information about employees. But, like health care providers, they should generally keep that information confidential. It’s granted to them for a limited class of purposes and should be seen only by people who require access to it for those reasons. (The federal rules are complicated, but the basic idea is that information about people’s health shouldn’t be given without their consent unless necessary.) Your dentist is entitled to know that employees are sick in order to confirm that they have medical reasons for taking sick days and to be sure that they pose no risks when they return to patient care. But precisely because the dentist was allowed the information necessary to decide whether the hygienist could safely be at work, patients in the clinic don’t need this information. The really important thing isn’t whether someone once had the virus but whether everyone in the clinic is taking the appropriate precautions with respect to hygiene and P.P.E. As it happens, people who have recovered from Covid-19 are thought to have immunity to it for some time, and people who have immunity to the virus are less likely to transmit it. So it doesn’t make sense to avoid a hygienist who has recovered. Someone who has never had the disease or has not been vaccinated poses the greater risk. (Though, again, a minimal one given proper precautions.)The C.D.C. says that someone who has had Covid-19 can be around others if 10 days have elapsed since symptoms began, a full day has elapsed without fever and other symptoms are improving. Although your dentist’s précis was inexact, it sounds as if the office erred on the side of safety and is rigorous about protocols. Your dentist was making the point that there was no clash here between employee privacy and the legitimate concerns of a patient. Possibly, though, I wouldn’t have added that slightly barbed final comment (“If this policy makes you uncomfortable, our office may not be a good fit for you”). Dentists, of all people, should understand the power and prevalence of irrational anxieties, and one element of good medicine is an understanding heart.I am a college student who spent my break working as an E.M.T. for a private ambulance service. My state’s Covid-19 vaccine protocol prioritizes first responders, and I have the option to receive a shot next week. Given that it can take up to a few weeks for the vaccine to promote antibodies, however, if I get the vaccine now, it won’t protect me until after I’m back at school. My early vaccination provides no benefit to the community, and I could be taking a dose from someone who is at greater risk. Is it wrong for me to get the vaccine knowing that if it weren’t for a few weeks of work, I would be waiting months? Elizabeth Hopkinson, MassachusettsA fair and reasonable system that isn’t unworkably complicated will end up vaccinating some people earlier than others whose need is greater. It’s not your job to add further criteria of your own. What’s more, the available evidence suggests that significant protection starts to kick in about 10 to 14 days after initial vaccination, which could overlap with your period of work as an E.M.T. And being vaccinated does provide a benefit to your community. It lowers the chance of your transmitting the disease by reducing the likelihood that you’ll contract it and, very likely, by reducing the likelihood that you’ll transmit it even if you do. Adding to the overall vaccination rate, which this does, will be necessary in order to reach something like herd immunity.An acquaintance asked me to refer him for an open position at my company. Normally, I would be happy to do so, but he mentioned that for New Year’s he rented a house in another state with a group of friends and later traveled to yet another state to ski. I think it is irresponsible of him to have engaged in recreational travel during the winter peak of the pandemic. The position he’s applying for is at a company where all employees currently work remotely. My concern is not that he’ll get anyone sick but that his recent travel indicates poor judgment, which may be obliquely relevant to his ability to do the job. Should I decline to refer him on these grounds or is that too big of a logical leap? Name WithheldYou’re not obliged to recommend an acquaintance for a job just because he asks. And if you do, you should not hide faults relevant to that job. But your resistance to recommending this person doesn’t seem to be that you think he wouldn’t do a good job; it’s that you disapprove of his behavior during the pandemic. As an empirical matter, though, there’s reason to doubt that people’s character traits are “global” — that the careful accountant is a careful driver, that the faithless spouse is a disloyal friend, that the effective product manager will share your sensible concerns about unnecessary travel and socializing. So yes, that’s a big logical leap. Still, you’re entitled to decline to recommend him because you think that he failed to display a concern for the common good; as an ethical matter, you can deny a favor to someone who, in your view, lacks an important virtue. What you can’t do is say you’ll recommend him and then not do so.I’m in a high-risk group, eligible for a Covid vaccination in both the state I live in and a neighboring state. My state is doing a poor job of distributing vaccines, and I’ve failed to get an appointment. But the neighboring state has a terrific system. A friend who lives there got me an appointment. I know that they don’t ask for your address when you arrive for your appointment, which suggests that they’re not overly concerned about residency, and my friend didn’t misrepresent me when signing me up. Am I right to feel a twinge of guilt all the same? Name WithheldDifferent states have different approaches. Our collective goal, as a nation, is to get as many people vaccinated — especially those at particular risk — as quickly as we can. But because states are allocated vaccines on the basis of their population, some are taking a firm line, restricting vaccinations to those who live or work there; they may require documentation or at least self-attestation to this effect. Other state officials seem OK with letting visitors in the line. So long as you don’t misrepresent yourself at any point, you can proceed with an easy conscience.Kwame Anthony Appiah teaches philosophy at N.Y.U. His books include “Cosmopolitanism,” “The Honor Code” and “The Lies That Bind: Rethinking Identity.” To submit a query: Send an email to ethicist@nytimes.com; or send mail to The Ethicist, The New York Times Magazine, 620 Eighth Avenue, New York, N.Y. 10018. (Include a daytime phone number.)

BRUSSELS — Citing what they call “the biggest challenge to the global community since the 1940s,” the leaders of 25 countries, the European Union and the World Health Organization on Tuesday floated an international treaty to protect the world from pandemics.In a joint article published in numerous newspapers across the globe, the leaders warn that the current coronavirus pandemic will inevitably be followed by others at some point. They outline a treaty meant to provide universal and equitable access to vaccines, medicines and diagnostics, a suggestion first made in November by Charles Michel, the president of the European Council, the body that represents the leaders of the European Union countries.The article argues that an international understanding similar to the one that followed World War II and that led to the United Nations is needed to build cross-border cooperation before the next global health crisis upends economies and lives. The current pandemic is “a stark and painful reminder that nobody is safe until everyone is safe,” the leaders write.The suggested treaty is an acknowledgment that the current system of international health institutions, symbolized by the relatively powerless World Health Organization, an agency of the United Nations, is inadequate to the problem.“There will be other pandemics and other major health emergencies. No single government or multilateral agency can address this threat alone,” the leaders note. “We believe that nations should work together toward a new international treaty for pandemic preparedness and response.”The treaty would call for better alert systems, data sharing, research and the production and distribution of vaccines, medicines, diagnostics and personal protective equipment, they said.“At a time when Covid-19 has exploited our weaknesses and divisions, we must seize this opportunity and come together as a global community for peaceful cooperation that extends beyond this crisis,” the leaders write. “Building our capacities and systems to do this will take time and require a sustained political, financial and societal commitment over many years.”The article is not clear, however, about what would happen should a country choose not to cooperate fully or to delay sharing scientific information, as China has been accused of doing with the W.H.O.China has not signed the letter, at least so far. Neither has the United States.In a news conference on Tuesday in Geneva, the director general of the World Health Organization, Tedros Adhanom Ghebreyesus, said that when discussions on a treaty start, “all member states will be represented.”Asked if the leaders of China, the United States and Russia had been asked to sign the letter, he said that some leaders had chosen to “opt in.”“Comment from member states, including the United States and China, was actually positive,” he said. “Next steps will be to involve all countries, and this is normal,” he added. “I don’t want it to be seen as a problem.”As well as European countries and the W.H.O., the letter’s signatories included nations in Africa, Asia and Latin America.Coronavirus World Map: Tracking the Global OutbreakThe virus has infected more than 127,627,400 people and has been detected in nearly every country.