Daniel Arlein has already had COVID-19. In March, the 36-year-old small business owner and DJ, who lives in Brooklyn, tested positive for the viral infection and suffered through two weeks of flu-like symptoms.
Arlein has since recovered, and while he’s still being careful — avoiding leaving the house, washing his hands more often and wearing a face mask — he can’t help feeling a bit relieved to have already had the infection.
“The only way it’s helping me is psychologically, to be able to go out in the world and still be careful but not be freaked out that I’m going to get sick,” he said. “I have no idea if I will get sick again. I feel like I won’t, but I have no idea if I can get it again.”
Most people understand immunity to mean that once a person has been exposed to a disease, they can’t get it again. It’s an easy concept to grasp, and some people have hoped that widespread immunity could be the way out of this pandemic: If enough of the population becomes immune to the disease, the spread would be stopped, since the virus would run out of new, susceptible targets. The “herd” of immune people would protect everyone.
But getting to herd immunity without a vaccine isn’t as simple as the idea itself. A number of variables can affect when herd immunity is reached — and what it costs to get there — and they vary depending on the disease. How infectious is the disease? How deadly is it? And how long do people stay immune once they’ve gotten it? Adjusting any of these variables can drastically change the outcome of this equation. You can probably sense where this is heading …
We’ve built a very simplified version of how those variables interact. (You’ll see just how simple in the methodology beneath the simulator.) To be clear, this is not about COVID-19 itself — instead, our calculator shows how a theoretical disease we’re calling Fictionitis would play out in a population that has never encountered it before and does nothing to try to stop it.
You’ll notice that each variable plays a role in setting a herd immunity threshold and reaching it.
The more people a person with Fictionitis infects on average, the higher the herd immunity threshold rises, but the faster spread also means that the threshold is reached more quickly. That, of course, can lead to a huge portion of the population getting ill at once, which would overwhelm hospitals. Unless the death rate is extremely low, that would be a devastating mix. A disease that doesn’t spread as readily will stick around for longer, but it helps maintain a flatter curve.
If you shortened the immunity duration, you may have also seen that the blue bar showing how much of the population is susceptible rose again even after the herd immunity threshold had been crossed. That’s because if immunity fades while the disease is still active, people who were previously immune once again become at risk for infection. Herd immunity only truly works while the recovered population has immunity to the disease.
For COVID-19, of course, we can’t change these variables, and we still haven’t nailed down their exact values, anyway. What we do know so far paints a stark picture: This disease is too deadly, too contagious and too new to depend on post-infection immunity (as opposed to immunity via vaccination) as a solution. Naturally acquired herd immunity is not the answer.
Read on for the details. They’re pretty compelling.
The road we would have to take to get to herd immunity is piled high with dead bodies. And while it might happen “faster” we shuld not want that. If you are fated to get this thing, you want to get it later not sooner — they are learning new things about this thing every day, new treatments, protocols, diagnostic tools. Maybe they’ll come up with some drug treatments that work.
Being in the herd is great unless you’re being trampled in a stampede.