Will Delta mutate into extinction?

Three months ago, Japan was struggling with its largest Covid wave yet, recording 23,000 new cases a day. But the infection rate has since dropped off a cliff—the country is now recording a mere 100 cases daily. Genetic experts say this sudden slump may be the result of the Delta variant mutating into self-extinction. When viruses replicate, “copying errors” in their genes change their characteristics—they might become more transmissible, for example, or better able to cause severe disease. But sometimes these mutations become evolutionary dead ends. Researchers at Japan’s National Institute of Genetics found that the Delta variant in Japan accumulated numerous mutations in an error-correcting protein before there was a sudden stop in the evolutionary process. “As the mutations piled up,” lead researcher Ituro Inoue tells The Japan Times, “we believe it eventually became a faulty virus and was unable to make copies of itself.” A similar case of self-extinction likely wiped out the SARS virus in the early 2000s, but this coronavirus is much more transmissible—making a natural global drop-off in cases highly unlikely. “The chances are not zero,” says Inoue, “but that seems too optimistic for now.”

Now a new study suggests these platforms can also leave middle-aged adults feeling down. Starting in May 2020, researchers spent a year surveying some 5,400 adults, with an average age of 56, about their mental health, reports NBCNews.com. Those who went on Facebook, TikTok, and Snapchat were much more likely to say they had become depressed than people who didn’t use social media, even after accounting for factors such as isolation during the pandemic. Different platforms appeared to affect different age groups: Depressive symptoms were more common in Facebook users under 35; for Snapchat and TikTok, such symptoms were more common in over-35s. The research doesn’t prove causation—people more vulnerable to depression may simply be more likely to use social media. But experts say the feelings of jealousy and envy that social media can trigger may have been accentuated when everyone was stuck at home. “Our brains were not built for this,” says Mitch Prinstein, from the American Psychological Association, who wasn’t involved with the study. “Social media is the empty calories of social interaction.”