Moderna on Friday sued Pfizer and BioNTech, alleging that their Covid vaccine copied its groundbreaking technology.Moderna said in a statement that Pfizer and BioNTech infringed on patents filed between 2010 and 2016 that covered its mRNA technology. Moderna sued in U.S. District Court in Massachusetts and the Regional Court of Düsseldorf in Germany, where BioNTech is based.Messenger RNA, or mRNA, is the genetic script that carries DNA instructions to each cell’s protein-making machinery and has been used in the production of coronavirus vaccines.“We are filing these lawsuits to protect the innovative mRNA technology platform that we pioneered, invested billions of dollars in creating, and patented during the decade preceding the COVID-19 pandemic,” said Stéphane Bancel, Moderna’s chief executive. “This foundational platform, which we began building in 2010, along with our patented work on coronaviruses in 2015 and 2016, enabled us to produce a safe and highly effective Covid-19 vaccine in record time after the pandemic struck.”This is a developing story.

The vaccine, which has been approved for adults, generated a strong immune response against both the original virus and the Omicron variant.British regulators on Monday approved the country’s first Covid-19 booster vaccine to target two coronavirus variants, the original virus and the Omicron variant.Half of each dose of the vaccine, or 25 micrograms, will target the original variant, and the other half will target Omicron. In clinical trials, the vaccine, an updated version of Moderna’s original Covid vaccine, generated a good immune response to these two variants, as well as the BA.4 and BA.5 subvariants in adults, researchers found.Dr. June Raine, the chief executive of Britain’s Medicines and Healthcare Products Regulatory Agency, said she was pleased that the new booster vaccine met the regulator’s standards of safety, quality and effectiveness. The decision was endorsed by Britain’s independent expert scientific advisory body, the Commission on Human Medicines.“The first generation of Covid-19 vaccines being used in the U.K. continue to provide important protection against the disease and save lives,” Dr. Raine said. “What this bivalent vaccine gives us is a sharpened tool in our armory to help protect us against this disease as the virus continues to evolve.”Side effects were the same as those seen for the original Moderna booster dose and were typically mild, with no serious safety concerns, British regulators said.The emergence of highly contagious Omicron subvariants this spring have appeared to reduce the protection offered by the Pfizer-BioNTech and Moderna vaccines against Covid hospitalizations, with more vaccinated people admitted to the hospital with Covid than they had been during the winter Omicron wave. But booster shots have raised people’s levels of protection, scientists from the U.S. Centers for Disease Control and Prevention said last month. The C.D.C. recommends that people receive booster shots as soon as they are eligible.

Three of the deaths involved direct contact with bats, the C.D.C. said.Five people in the United States died from rabies last year, the highest number in a decade, the Centers for Disease Control and Prevention said Thursday.Three of those deaths, including that of a child, involved direct contact with bats and occurred over a five-week period starting in late September. The deaths occurred in Idaho, Illinois and Texas, and all three victims experienced symptoms three to seven weeks after contact with bats. They died two to three weeks after symptoms began, according to a C.D.C. report.Rabies is caused by a virus that is usually transmitted through the saliva of an infected animal through a bite. It has one of the highest mortality rates of any disease, but death is preventable: Vaccines taken before symptoms appear are nearly 100 percent effective. Still, rabies causes about 59,000 deaths around the world each year, 40 percent of which occur in Africa and Asia, according to the World Health Organization.Most of the deaths occur in countries where public health resources are inadequate. In the United States, death from rabies is exceedingly rare — in 2019 and 2020, there were no reported cases or deaths. The C.D.C. said the uptick in rabies cases could be because of a lack of awareness about the risks, since the number of rabid bats that have been reported to the National Rabies Surveillance System has been stable since 2007.Four of the five people who died in late 2021 did not receive the vaccine, according to the C.D.C. Two of the patients did not take vaccines because they did not know about the risk of rabies from their exposures, either because they did not notice a bite or scratch or because they did not recognize the risks of getting rabies from bats, the C.D.C. said.“We have come a long way in the United States toward reducing the number of people who become infected each year with rabies,” said Ryan Wallace, a veterinarian and rabies expert at the C.D.C., “but this recent spate of cases is a sobering reminder that contact with bats poses a real health risk.”Once the virus reaches the brain, it can cause convulsions, fear of water, excessive salivation and other symptoms. Eventually the infection causes coma and death.Once symptoms start, rabies is nearly always fatal.In one case, an 80-year-old man in Illinois who had a bat roost in his home awoke in August to find a bat on his neck, according to a statement from the Illinois Department of Public Health. The bat was captured and tested positive for rabies, but the man declined to take a vaccine because of a longstanding fear of vaccines. About a month after contact with the rabid bat, the man started experiencing neck pain, headaches, difficulty controlling his arms, finger numbness and difficulty speaking, before dying.In another case, a child in Texas picked up a bat with his bare hands and then released it. A third person died in New York after he was bitten by a dog in the Philippines. He started developing symptoms after he returned to the United States, and the C.D.C. was not able to determine why he did not receive a vaccine.A fourth person from Minnesota who died from rabies last year received the vaccine but his weakened immune system did not respond to it, the C.D.C. said.In the early 1900s, more than 100 people in the United States died of rabies every year. That number fell to one or two per year since 1960 as pet vaccination, animal control programs and public health surveillance improved, and the rabies vaccine became more available. In 2018, three people died from rabies, the second highest number in the past few years. In 2011, six people died from rabies.In many countries, the greatest risks of rabies are from stray, unvaccinated dogs. In the United States, however, about 70 percent of rabies infections are from exposure to bats. The C.D.C. urges people to avoid contact with bats. If contact occurs, people should talk to their doctors or local public health officials to determine whether rabies vaccines are needed. Bat bites or scratches can be very small and in some cases not visible.When it is unclear whether there was contact with a bat, such as in cases where bats enter homes while people were sleeping or if children were left unattended, it is essential that people immediately call local health officials for guidance. About 60,000 people receive rabies vaccines each year, according to a C.D.C. estimate.

A new study questions that figure, known as Dunbar’s number. The Oxford professor for whom it is named, Robin Dunbar, dismissed the new findings as “absolutely bonkers.”LONDON — Just how many friends can one person have?In a 1993 study, Robin Dunbar, a British anthropologist, theorized that humans could have no more than about 150 meaningful relationships, a measure that became known as Dunbar’s number.But researchers at Stockholm University published a paper last week calling that number into question, finding that people could have far more friends if they put in the effort.“We can learn thousands of digits of pi, and if we engage with lots of people, then we will become better at having relationships with lots of people,” said Johan Lind, an author of the study and an associate professor at Stockholm University. The paper was published in the journal Biology Letters.In his original research, Dr. Dunbar studied monkeys and apes and determined that the size of the neocortex, the part of the brain responsible for conscious thought, correlated with the size of the groups they lived among. The neocortex in humans is even larger, so he extrapolated that their ideal group size was, on average, 150.In the new study, Dr. Lind said he and his team used updated data sets and statistical methods and found that the size of the neocortex did not limit the number of connections people could maintain. Dunbar’s number, he said, “has been criticized for quite a long time.” Dr. Lind’s team found that no maximum number of friendships could be established with any precision.In an interview, Dr. Dunbar, a professor of evolutionary psychology at Oxford University, defended his research. The new analysis, he said, “is bonkers, absolutely bonkers,” adding that the Stockholm University researchers conducted a flawed statistical analysis and misunderstood both the nuances of his analyses and of human connections. “I marvel at their apparent failure to understand relationships.”Dr. Dunbar defines meaningful relationships as those people you know well enough to greet without feeling awkward if you ran into them in an airport lounge. That number typically ranges from 100 to 250, with the average around 150, he said.At birth, it starts at one or two. Friendships peak in the late teens and early 20s. By their 30s, people tend to have about 150 connections, and that number remains flat until people reach their late 60s and early 70s, when their number of connections, Dr. Dunbar said, “starts to plummet.” “If you live long enough, it gets back to one or two.”In his book “How Many Friends Does One Person Need,” Dr. Dunbar pointed to historical and modern-day examples to back up his research. Around 6000 B.C., the size of Neolithic villages from the Middle East was 120 to 150 people, judging by the number of dwellings. In 1086, the average size of most English villages recorded in the Domesday Book was 160 people. In modern armies, fighting units contain an average of 130 to 150 people, he said.In 2007, when the Swedish tax agency was restructuring, a strategist for the agency proposed that each of the new offices have about 100 to 150 employees, citing Dr. Dunbar’s research. Employees, already unhappy with the restructuring, got wind of the plan and complained about being compared to monkeys. (Dunbar’s number did not, in the end, play any role in the agency’s restructuring, according to three officials involved with the plans.)While it may be comforting to think that there is an optimal number of people with whom we should surround ourselves, in reality there is not one rule that applies to all of us, said Louise Barrett, a psychology professor at the University of Lethbridge in Canada. “Human life is really complicated,” she said.Dr. Barrett, a biological anthropologist who was not involved in the new study and who previously studied under Dr. Dunbar, said the analysis looked robust. “We need to rethink and adjust our interpretation and hypotheses in light of this new data,” she said.The debate over relationships comes as people are rethinking which friendships they want to recultivate after the pandemic shrank social circles and as businesses are designing post-pandemic work spaces.The British academic and anthropologist Robin Dunbar has said people can maintain about 150 meaningful relationships.Colin McPherson/Corbis, via Getty ImagesDr. Dunbar posited his theory decades ago, in the early days of the internet and long before social media sites changed how people communicate. “This number would make sense if we still relied on a Rolodex and talking to people, but that’s not the world we live in,” said Angela Lee, a professor at Columbia Business School.Networking tools like LinkedIn have made it possible to increase the number of connections we can maintain, and this is important because research shows that people on the outer edge of our networks are often the ones who end up being the most helpful for career advancement or generating creative ideas, she said.Dr. Dunbar contended that his theory is still viable, even in today’s hyper-connected world, since the quality of connections on social networks is often low. “These are not personalized relationships,” he said.What will the pandemic mean for rebuilding meaningful connections, whether at work or in our social lives? It is probably too early to say, but Dr. Dunbar predicted that the biggest effects on networks would be on older people. “Their friendship circles were already declining and this will push them further down that slope,” he said.Dr. Dunbar said that, while he tries not to analyze himself, he guessed he had about 150 friends.“It’s fairly blatantly obvious to most people when they sit down and think about it that that’s how their social network is organized,” he said. Dunbar’s number, he said, is not going anywhere.