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It was H5N1, or “avian flu,” discovered two decades prior, but known only to infect birds.
By then, it was August. Scientists sent distress signals around the world. The Chinese government swiftly killed 1.5 million chickens (over the protests of chicken farmers). Further cases were closely monitored and isolated. By the end of the year there were 18 known cases in humans. Six people died.
This was seen as a successful global response, and the virus was not seen again for years. In part, containment was possible because the disease was so severe: Those who got it became manifestly, extremely ill. H5N1 has a fatality rate of around 60 percent—if you get it, you’re likely to die. Yet since 2003, the virus has killed only 455 people. The much “milder” flu viruses, by contrast, kill fewer than 0.1 percent of people they infect, on average, but are responsible for hundreds of thousands of deaths every year.
Severe illness caused by viruses such as H5N1 also means that infected people can be identified and isolated, or that they died quickly. They do not walk around feeling just a little under the weather, seeding the virus. The new coronavirus (known technically as SARS-CoV-2) that has been spreading around the world can cause a respiratory illness that can be severe. The disease (known as COVID-19) seems to have a fatality rate of less than 2 percent—exponentially lower than most outbreaks that make global news. The virus has raised alarm not despite that low fatality rate, but because of it.
Coronaviruses are similar to influenza viruses in that they are both single strands of RNA. Four coronaviruses commonly infect humans, causing colds. These are believed to have evolved in humans to maximize their own spread—which means sickening, but not killing, people. By contrast, the two prior novel coronavirus outbreaks—SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome, named for where the first outbreak occurred)—were picked up from animals, as was H5N1. These diseases were highly fatal to humans. If there were mild or asymptomatic cases, they were extremely few. Had there been more of them, the disease would have spread widely. Ultimately, SARS and MERS each killed fewer than 1,000 people.
COVID-19 is already reported to have killed more than twice that number. With its potent mix of characteristics, this virus is unlike most that capture popular attention: It is deadly, but not too deadly. It makes people sick, but not in predictable, uniquely identifiable ways. Last week, 14 Americans tested positive on a cruise ship in Japan despite feeling fine—the new virus may be most dangerous because, it seems, it may sometimes cause no symptoms at all.
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Much more:
https://www.theatlantic.com/health/a...accine/607000/
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