“Well, yeah,” said Becks. “It’s part of the standard set of field vaccines.”

“For a long time, they didn’t have a vaccine for chickenpox—it was a childhood disease, and almost everybody caught it. Only that was a good thing back then, because most kids get over the chickenpox pretty easy. They itch for a week and then they’re fine. Better than fine. Having the virus once makes them resistant to catching it again, and for adults, chickenpox is no laughing matter. It can cause permanent nerve damage, severe scarring, all sorts of nasty side effects.r Dr. Abbey looked placidly at Kelly. “People used to have chickenpox parties, where they’d deliberately expose their young children to somebody who was already sick.”

“That’s disgusting,” said Becks.

“Now that we have a vaccine, sure. Back then, it was a way to save your children from suffering a lot more. It wasn’t safe—kids died of chickenpox—but it was a damn sight better than the alternative.”

“I don’t understand,” I said.

I do, said George, very quietly.

“I do,” echoed Alaric. I turned to look at him, and he said, “When infants are exposed to live Kellis-Amberlee, they can’t amplify, but they still get sick. Only they can get better, can’t they? They can actually recover from the virus.”

“Bingo.” Dr. Abbey, touching her nose with her left index finger while she pointed at Alaric with her right. “Princess CDC, tell the nice man what he’s won!”

Kelly was silent.

I swallowed away the dryness in my throat, and said, quietly, “Please.”

My voice seemed very loud in the enclosed space of the lab. Kelly turned to face me and said, “Yes, sometimes early exposure can lead to individuals successfully fighting off a live Kellis-Amberlee infection. It’s impossible to run a standard blood test on an infant, because they can’t amplify, so we can’t find the usual amplification markers. But they’ll get sick. It’s been seen. And then, after a little while, they aren’t sick anymore.” Kelly stopped, choosing her next words with care: “Most of the individuals who undergo a potential infectious episode as infants develop one of the reservoir conditions when they get older, because their immune systems are preconditioned to respond.”

“Their bodies remember that the virus is bad, and they set up their own little kennels, filled with their own little packs of domesticated viral bodies,” clarified Dr. Abbey, leaning down to thump Joe on the side. He looked up at her adoringly, tongue lolling. “That’s what humanity does when faced with wolves. We take them in, tame them, and teach them how to keep us safe.”

“Yes,” agreed Kelly. “The reservoir conditions are a marker that the immune system has learned it needs to fight back when Kellis-Amberlee starts taking over.”

“That’s why you said she would’ve gotten better, isn’t it?” Kelly didn’t answer. I slammed my fist into the safety-glass window, hard enough to make everyone jump—everyone but Dr. Abbey, who looked like she’d plugged herself into some inner reservoir of contentment. “Answer the damn question, Doc.”

“Yes.” Kelly looked up at me, expression drawn. “Dr. Wynne and I reviewed her test results. Her immune system was already starting to respond to the new infection when the test was taken. The chances that she would have been able to fight off the infection were very good. Better than eighty percent.”

“Spontaneous remission,” said Alaric, sounding awed.

I didn’t take my eyes off Kelly as I said, “Explain.”

“It’s supposed to be an urban legend. Supposedly, there are people who’ve been infected—like, full-on ready-to-eat-the-neighbors infected—but they miraculously recovered before they could be put down. Nobody ever seems to know anyone who’s had a spontaneous remission. It’s always a guy who knows a guy who used to know a guy. But the stories keep cropping up, and then the CDC reminds everyone that there’s no cure and they get written off again.”

“Guess it’s not that much of a legend, huh, Doc?” I glanced toward Dr. Abbey. “Is that what we’re talking about here? This remission thing?”

“The CDC is telling the truth about one thing: There’s no cure for Kellis-Amberlee, and if someone offered me one, I wouldn’t take it, for a lot of reasons. They’re also lying, because if you can live with the virus from the time you’re born, why the hell should it be able to wake up but not able to go back to sleep?” Dr. Abbey smiled encouragingly. “Isn’t story hour fun?”

“Like a heart attack,” I said.

“Two in ten thousand,” said Kelly sharply.

“What?” I asked.

“Two in ten thousand.” She stood, ignoring the gun Becks had trained on her. “That’s how many people with existing reservoir conditions are likely to recover from a live infection. Two in ten thousand. No one who didn’t have a reservoir condition has ever recovered. The rate of recovery seems to be tied to the density of the viral particles in the individual reservoir, but we don’t have any hard-and-fast proof of that. It’s not like we’ve had much opportunity for study, since you can’t exactly get volunteers for that sort of thing.”

“Not even from the prison system,” deadpanned Maggie.

Kelly winced again. I didn’t really give a f**k. If she wanted to feel guilty, she’d damn well earned her guilt. “It’s not like that,” she said.