The Plague virus requires the absence of a specific gene sequence. The body’s resistance to the Plague—through its ability to fight the high white blood cell count it generates with speed—is present in the X chromosome. In around 9 percent of men their X chromosome has the necessary genetic protection. Thanks to their XX chromosomes, all women are safe. The others, the billions of other men, are vulnerable to the virus.
“How did you find it?” George asks her. “How did you know?”
“I’ve been treating two sets of twins,” Amaya says, her face for the first time revealing the weariness of a medical professional in the post-Plague world as though a curtain has been pulled to the side of her calm, well-rested fa?ade. “One set of male identical twins were both immune but their father was not. A set of male fraternal twins had an immune father but only one of the twins was immune. The other died. Basic genetic logic. And the luck of any of my patients being immune.”
George nods. “We’ve been doing the workings, so to speak, and we’re nearly there with the coding. The theory works, but we need to know why.”
“It also explains why women are asymptomatic hosts,” I add.
“It bothered me that we knew but didn’t know why,” Amaya says with a sigh. “Amanda Maclean was talking about it right from the beginning because she identified a female nurse as a cause of the spread of infection in her A and E Department.”
“Like with many things in the story of the Plague, Amanda was way ahead of the rest of the world,” George says.
Amaya pauses, looks at George thoughtfully. “I have to say, it’s a pleasant surprise to be sitting with a male doctor, discussing all of this. There’s not many of you left.”
George smiles in response, almost apologetically. “I’m immune. We tested my blood and Elizabeth personally looked at it under a microscope. I carry the virus but I’m asymptomatic. We’re working on a test for immunity, trying to identify the specific genetic markers. This will obviously help enormously.”
“We’re an army of hosts,” Amaya says with sad sigh. “Spreading it all around. How close are you to a vaccine?” George was cautious about saying anything on the phone about our progress, or lack thereof. It’s crucial that the difficulties we’re having finding a vaccine are not leaked to the public, unplanned and unfiltered. We can see the headlines writing themselves.
George looks at me, as if to say, “Do you want to take this one or shall I?” I decide to take one for the team. “We’ve not made a lot of progress,” I say, trying to lift the sentence with some optimism. “But we’re working on it, and we’ve managed to discount some options. The virus is very unstable, it’s hard to—well, you understand.”
Amaya’s face has dropped and I realize that the only thing scarier than knowledge is the lack of it. At least I know the details of what is being done, the scant information coming from other countries’ vaccine programs, the small steps forward we’ve made in our analysis of immunity. Amaya, until now, has probably been able to convince herself that the task force was close to success.
“I feared that might be the case,” she says, twisting her wedding band round her finger. It’s loose; she must have lost weight, grief most likely. It’s not a great leap to assume she’s now a widow.
I want to make her feel better. “We will get there, we’re closer than we were, but everything you’ve done is going to change a lot. Your discovery, the understanding of the genetics of male vulnerability, will make it so much easier. Truly, you’ve done something extraordinary.”
Later that afternoon, once Amaya has returned to her patients at Great Ormond Street, George and I talk. We have a few more weeks of work to do, finalizing the genetic sequencing and then what?
“We have to release it,” George says. I nod in agreement.