Reader TTS

WHAT THE SPANISH FLU TELLS US After sweeping the globe for more than a year, COVID-19 won't just disappear. But it could eventually evolve into something more similar to the flu or even

the common cold, Wherry says, although that could take years, decades or more. The last major pandemic, which took place a century ago, could offer a few hints. In 1918 and 1919, the

Spanish flu killed at least 50 million people around the globe (so far, COVID-19 has killed fewer than 3 million people worldwide). The virus finally receded mainly because much of the

world's population had already been exposed and developed immunity or died. But although the pandemic ended, the virus never really went away. In fact, descendants of the 1918 flu virus

caused deadly outbreaks in 1957, 1968 and 2009. "The 1918 virus accumulated many changes over the years, and there are still genetic remnants in the H1N1 viral strain out there today,”

Schaffner says. “It's like generations of people. A little bit of your great-great-grandfather's genes are in you, so the current influenza virus has some of its

great-great-grandparents’ flu genes.” Likewise, SARS-CoV-2, the virus that causes COVID-19, has already begun to mutate. The question is how the virus will change. Most mutations in other

viruses don't have any meaningful impact on the way the virus behaves, and some mutations can even be detrimental to the virus. In other instances, viruses can mutate to spread more

easily or evade the body's immune response. "The problem is that one small little change can make a virus very harmful,” says Gustavo Caetano-Anollés, a computational biologist and

biochemist at the University of Illinois at Urbana-Champaign who studies the evolution of viruses. “The difference between COVID and influenza is that humans have been exposed to [the flu]

for so long and have been generating immunities for so long, it pushes down the toll of the disease.” You may not think of the flu as a major concern today, but it still kills between 12,000

and 61,000 people in the U.S. each year and hospitalizes hundreds of thousands more. If the fatality and hospitalization rates for COVID-19 eventually decline to those of the flu — and

that's still an if, Rock notes — it would still represent a significant burden. "Influenza kills thousands of people every year, mostly older adults, and causes a huge strain on

health systems,” she says. “And we could have twice as much COVID-19 as flu every year.”