"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," he writes. "A part of you suspects that this whole thing might be overblown."
What he doesn't realize is his friend's father had already unknowingly contracted COVID-19 at a conference, and coughed into his hand before opening the door to his son three days earlier.
"The saliva of COVID-19 patients can harbor half a trillion virus particles per teaspoon, and a cough aerosolizes it into a diffuse mist," he wrote. "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."
As he talks across the table, 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"; settling on the food, his fingers, and even straight into his nose and 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."
The article goes onto explain how the virus particles settle into "warm, wet surfaces" of the mucus coating the tissue of your lungs.
The outside of each particle is covered in spiky protrusions like a "knobby ball chew toy"; inside is a coiled strand of RNA -- the virus payload.
After meeting a cell in the lung, it matches its shape, fuses with it and spills its contents inside.
Working normally, the cell is "like Santa's workshop, where the elves, dutifully hammering out the toys on Santa's instructions"; but the viral RNA hijacks the machinery and begins countlessly replicating itself.
The components collect in internal bubbles "that move to the surface, burst open, and release new virus particles into your body by the tens and hundreds of thousands."
"Meanwhile, spike proteins that haven't been incorporated into new viruses embed themselves directly into the host cell's membrane so that it latches onto the surface of an adjacent cell, like a pirate ship lashing itself to a helpless merchantman. The two cells then fuse, and a whole host of viral RNA swarms over into the new host cell."
This process replicates up and down the lungs, throat, mouth, through the bloodstream and digestive system.
While all of this is going on, most scarily of all, the author feels completely fine - his only complaint during self quarantine, is boredom. So he calls up an ex to go for a walk together, which they do, before hugging her goodbye.
"What she doesn't know is that an hour before, you went to the bathroom and neglected to wash your hands afterward. The invisible fecal smear you leave on the arm of her jacket contains 893,405 virus particles."
"Forty-seven seconds after she gets home, she'll hang up her coat and then scratch an itch at the base of her nose just before she washes her hands. In that moment, 9,404 viral particles will transfer to her face. In five days, an ambulance will take her to Mount Sinai."
Only now, as remnants of the hijacked and infected cells that have been burnt out begin to float through the bloodstream, does the immune system finally suspect something is wrong.
Fever kicks in as the body begins to fight the infection. The author is not worried as he knows the virus is really only dangerous to older people. But for reasons scientists don't yet understand, one in five younger people who get infected become seriously ill... and he's about to become one of them.
The jarring story goes on to describe how the author's body continues to break down as the immune system goes into overdrive, attacking everything in the body -- virus and healthy cells alike.
Fluttering on the edge between life and death, doctors desperately delegate many of his organ functions to machines. "Your odds are 50-50 or worse. Owing to the fact that the pandemic has stretched the hospital's resources past the breaking point, your outlook is even bleaker."
Be warned; if you're hoping the story has a happy ending, finish reading that reassuring epilogue at the penultimate par.