It always starts quietly. Just a few cases, a couple of infected animals, and some scientists raising cautious concerns. Then suddenly, it spreads fast. Remember March 2020, when “lockdown” became part of everyday life? What if something similar is already happening again—and we just haven’t noticed yet?

The person sounding the alarm this time is David Quammen, the same writer who warned us before COVID-19.

David Quammen: The Man Who Saw It Coming

David Quammen isn’t a fortune teller, but his past predictions were spot on. In his book Spillover, written before the COVID-19 pandemic, he warned about zoonoses—diseases that jump from animals to humans. At the time, some thought he was being overly cautious. But the pandemic proved he had a point.

Now, he’s focused on another virus: H5N1, better known as bird flu. It’s not new, but recent changes in the virus and how quickly it’s spreading have scientists worried.

Bird Flu Is Already Spreading in Animals

This isn’t just a “what if” situation anymore. In April 2025, H5N1 was found in a sheep in the UK—something that had never happened there before. Over in the U.S., things are even more serious. The virus has hit over 1,000 dairy farms, led to the culling of more than 168 million birds, and infected at least 70 people. One person has died.

This isn’t a plot from a movie—this is real. The virus is spreading not just in birds, but in mammals too, which makes it more likely to jump to humans.