You call a friend and arrange to meet for lunch. It’s unseasonably springlike, so you choose a place with outdoor seating, which seems like it should be safer. As usual, you take all reasonable precautions: You use hand sanitizer, sit a good distance from other customers, and try to avoid touching your face, though that last part is hard. A part of you suspects that this whole thing might be overblown.
What you don’t know is that ten days ago, your friend’s father was a guest of his business partner at the University Club, where he caught the novel coronavirus from the wife of a cryptocurrency speculator. Three days after that, he coughed into his hand before opening the door of his apartment to welcome his son home. The saliva of COVID-19 patients can harbor half a trillion virus particles per teaspoon, and a cough aerosolizes it into a diffuse mist. As your friend walked through the door he took a breath and 32,456 virus particles settled onto the lining of his mouth and throat.
Viruses have been multiplying inside his body ever since. And as he talks, the passage of his breath over the moist lining of his upper throat creates tiny droplets of virus-laden mucus that waft invisibly into the air over your table. Some settle on the as-yet-uneaten food on your plate, some drift onto your fingers, others are drawn into your nasal sinus or settle into your throat. By the time you extend your hand to shake good-bye, your body is carrying 43,654 virus particles. By the time you’re done shaking hands, that number is up to 312,405
One of the droplets gets drawn into the branching passages of your lungs and settles on the warm, wet surface, depositing virus particles into the mucus coating the tissue. Each particle is round and very small; if you magnified a human hair so that it was as wide as a football field, the virus particle would be four inches across. The outer membrane of the virus consists of an oily layer embedded with jagged protein molecules called spike proteins. These stick out like the protrusions on a knobby ball chew toy. In the middle of the virus particle is a coiled strand of RNA, the virus’s genetic material. The payload.
As the virus drifts through the lung’s mucus, it bumps into one of the cells that line the surface. The cell is considerably larger than the virus; on the football-field scale, it’s 26 feet across. A billion years of evolution have equipped it to resist attackers. But it also has a vulnerability — a backdoor. Protruding from its surface is a chunk of protein called angiotensin converting enzyme 2, or ACE2 receptor. Normally, this molecule plays a role in modulating hormone activity within the body. Today, it’s going to serve as an anchor for the coronavirus. Continue reading New York: How the Coronavirus Could Take Over Your Body (Before You Ever Feel It)