Until recently, the general uptick in respiratory illness in the winter was blamed on the fact that people spend more time indoors together, swapping viruses, in cooler weather. That’s likely a factor, but cold is also directly, not just indirectly, responsible for making us sick, thanks to a previously unknown immune mechanism: cells in our nostrils that are capable of detecting incoming microbes and releasing a swarm of tiny little antiviral bubbles to surround and neutralize them.
