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Two years into the Covid-19 pandemic, America’s death toll is closing in on one million. Federal authorities estimate that 987,456 more people have died since early 2020 than would have otherwise been expected, based on long-term trends. People killed by coronavirus infections account for the overwhelming majority of cases. Thousands more died from derivative causes, like disruptions in their healthcare and a spike in overdoses.Covid-19 has left the same proportion of the population dead—about 0.3%—as did World War II, and in less time. (Kamp, Levitz, Abbott and Overberg, 1/31)

To understand how the coronavirus keeps evolving into surprising new variants with new mutations, it helps to have some context: The virus’s genome is 30,000 letters long, which means that the number of possible mutation combinations is mind-bogglingly huge. As Jesse Bloom, a virologist at the Fred Hutchinson Cancer Research Center, told me, that number far, far exceeds the number of atoms in the known universe. (Zhang, 1/29)

Around Dec. 19, 2021, John and Bridget Rooks got a call from their daycare asking them to pick up their kids after another child tested positive for coronavirus. Such calls have become a regular occurrence for countless parents over the course of the pandemic, with the disruptions leading to lost workdays, burnout, and even feelings of despair. “You can’t plan for it because you never know when it’s going to happen,” said John Rooks, an attorney who has two children, aged 4 years and 8 months, in daycare in Chicago’s Logan Square neighborhood. With the December case, he noted, “it was just ‘Come pick up your kids and we’ll see you after the New Year.” (Roberts, 2/2)

Blink and you could have missed it. For six months, the United States experimented with an idea that's new here but is already a backstitch in the social fabric of many wealthy nations: a monthly cash payment to help families cover the costs of raising children. Less than a year in, though, this U.S. experiment, known as the expanded child tax credit, has already been unwound by a deadlocked Congress. Still, it's worth asking: What did it accomplish? Here's what the data tells us. (Turner, 1/27)

Whether you’re landing down from a basketball layup or simply stepping off a street curb, your body must be able to decelerate with control. “If you can’t harness your power, you misstep and fall,” says Ann Crosby, strength and conditioning coach for the Women’s National Basketball Association’s 2021 championship team, the Chicago Sky. (Murphy, 1/29)

When you take a whiff of something, odor molecules sail inside your nose where they bind to proteins — called olfactory receptors — on cells that line your nasal cavity. These receptors trigger signals that your brain interprets as one or many smells. A team of scientists has identified the olfactory receptors for two common odor molecules: a musk found in soaps and perfumes and a compound prominent in smelly underarm sweat. The research team also discovered that more recent evolutionary changes to these olfactory receptors alter people’s sensitivities to those odors. The work was published in PLoS Genetics on Thursday. (Jones, 2/3)

A group of medical school friends nominated Sasha Hamadi to create a memory book for their pregnant classmate. Hamadi worked hard on the task for several weeks. She printed pictures, gathered mementos and listened to stories about their friend. The book — meant to be a group gift for their classmate’s baby shower — was more than 100 pages long, with items such as anatomy class doodles and fabric from a white medical coat. On the flight to the baby shower from Kansas, Hamadi realized when she was searching in her bag for her headphones that she had left the memory book behind. She felt awful. “I’m sure that half of the people here thought I never even made anything,” she recalled thinking. Hamadi, now 35, was diagnosed with attention-deficit/hyperactivity disorder at age 9. She frequently misplaces important items, runs late or struggles with a disorganized purse — all symptoms of ADHD. She has been labeled a “flake” because she forgets social engagements or to reply to texts. People have often told her, “If it was important to you, you’d remember.” (Maguire, 2/3)

Research that just unlocked how an antibiotic-resistant superbug evolved on one of nature’s prickliest mammals is an important reminder for humans: Bacteria are often very good at outmaneuvering the antibiotics designed to kill them. By swabbing the skin, feet and nasal areas of nearly 300 hedgehogs, a joint international study shows how one strain of MRSA, or a bacteria known as methicillin-resistant Staphylococcus aureus, has developed antibiotic resistance in nature. Findings from researchers at the University of Cambridge, Denmark’s Serum Statens Institut and several other research institutions suggest the process is a result of a microscopic competition between the bacteria and a specific type of fungus, both found on the skin of the little, spiky critters. (Isaacs-Thomas, 2/3)

In June 2017, Betty Balikagala traveled to a hospital in Gulu District, in northern Uganda. It was the rainy season: a peak time for malaria transmission. Balikagala, a researcher at Juntendo University in Japan, was back in her home country to hunt for mutations in the parasite that causes the disease. For about four weeks, Balikagala and her colleagues collected blood from infected patients as they were treated with a powerful cocktail of antimalarial drugs. After initial analysis, the team then shipped their samples — glass slides smeared with blood, and filter papers with blood spots — back to Japan. (Pawar, 1/26)