Our most recent flu pandemic—2009’s H1N1 “swine flu”—was, in absolute terms, a public-health crisis. By scientists’ best estimates, roughl

How Much Worse Would a Bird-Flu Pandemic Be?

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2024-06-10 01:00:05

Our most recent flu pandemic—2009’s H1N1 “swine flu”—was, in absolute terms, a public-health crisis. By scientists’ best estimates, roughly 200,000 to 300,000 people around the world died; countless more fell sick. Kids, younger adults, and pregnant people were hit especially hard.

That said, it could have been far worse. Of the known flu pandemics, 2009’s took the fewest lives; during the H1N1 pandemic that preceded it, which began in 1918, a flu virus infected an estimated 500 million people worldwide, at least 50 million of whom died. Even some recent seasonal flus have killed more people than swine flu did. With swine flu, “we got lucky,” Seema Lakdawala, a virologist at Emory University, told me. H5N1 avian flu, which has been transmitting wildly among animals, has not yet spread in earnest among humans. Should that change, though, the world’s next flu pandemic might not afford us the same break.

Swine flu caught scientists by surprise. At the time, many researchers were dead certain that an H5N1, erupting out of somewhere in Asia, would be the next Big Bad Flu. Their focus was on birds; hardly anyone was watching the pigs. But the virus, a descendant of the devastating flu strain that caused the 1918 pandemic, found its way into swine and rapidly gained the ability to hack into human airway cells. It was also great at traveling airborne—features that made it well positioned to wreak global havoc, Lakdawala said. By the time experts caught on to swine flu’s true threat, “we were already seeing a ton of human cases,” Nahid Bhadelia, the founding director of the Boston University Center on Emerging Infectious Diseases, told me. Researchers had to scramble to catch up. But testing was intermittent, and reporting of cases was inconsistent, making it difficult for scientists to get a handle on the virus’s spread. Months passed before the rollout of a new vaccine began, and uptake was meager. Even in well-resourced countries such as the U.S., few protections hindered the virus’s initial onslaught.