Daily MoS: Herd Immunity

Amongst epidemiologists, an unpopular way to approach the pandemic has been dubbed the “herd immunity” approach. In this method, a population attempts to control the disease by *checks clipboard* getting the disease en masse, so it seems. Isolate at-risk populations, then healthy people should all go out and get exposed to help shield the at-risk people with their Care Bear stare of immunity and wishful thinking.

Given the nursing home outbreaks, all the gatherings with grandparents for holidays, the ICUs in Stockholm that are reportedly at capacity, and, um, all the dead people, we’re due for an explainer on why we’ve been wrongy mcwrongface.

Today in a Moment of Science… becoming a responsible member of the herd.

If you’re unclear on how herd immunity works and think “what good is the herd immunity tactic if it means I gotta lick a rat?” that’s not surprising. It’s a simple concept that a lot of internet libertarians have been incorrectly explaining for a year as the savior of the economy. I can understand the confusion.

The TL;DR version is that a sufficient level of a population is immune to contain and slow disease outbreak, keeping vulnerable populations protected. But I implore you to stick around for the colorful fucking version.

In order to better understand herd immunity for covid, let’s think about a disease that my fellow elder millenials and older are almost universally acquainted with: chicken pox. Until a certain point, most of us itched and scratched our way to immunity. A vaccine was first introduced abroad in 1988 and in the US in 1995. As of 2014 in the US, 95% of 17 year olds had received at least one dose of the chicken pox vaccine.

More importantly about chicken pox, it has something in common with covid; they’re both far milder for children, and lethality rates skyrocket in adulthood. But most of us spent our wee years projectile blasting bodily fluids on our parents as signs of a healthy immune system gradually figuring out the world one microbe at a time. So before the vaccine, annual chickenpox infections were similar to annual birth rates. We had a sort of rolling herd immunity from childhood infections.

However, since the vaccine was introduced, hospitalizations and fatalities from chicken pox have plummeted. People who received the vaccine are also not at risk for shingles. Crazy talk here, but getting immunity without the disease may just be the less shit option.

Now, if you missed getting chickenpox as a child, you can get vaccinated as an adult. But since some people cannot be vaccinated, we still have people at higher risk of fatality to this “harmless childhood disease.” And the point of herd immunity isn’t to stop outbreaks (you need eradication for that). It means when an outbreak occurs, there are limited juicy little disease vectors for the virus to feast on. This makes people who are at high risk more easily protected when the disease can’t spread like a wildfire through the herd. And the safest way to accomplish that, when we can, is via vaccination.

That’s herd immunity.

So then, let’s tackle why herd immunity is not a “tactic” for beating an active pandemic with a large swath of at risk people. There have already been simply absurd suggestions that we were approaching herd immunity months ago. With only (give or take) ten percent of the population immune so far via catching covid? This is like telling us we’re all protected with just ten percent of a condom, we have to keep fucking to make the rest of the condom come along, we’re not sure who’s at high risk of becoming pregnant or who’s contagious with the new highly infectious chlamydia variant but it’s okay because we’ll all be immune soon if we all keep fucking, pay no mind to the airborne babies that you’re contagious with before you know you’re pregnant. Or something.

Oof.

Building herd immunity via purposefully getting sick with a disease that poses a high chance of chronic health problems defeats the purpose of herd immunity. Until we can perfectly wall off everyone who’s at risk, you’re going to have to admit to yourself that you’re not “building herd immunity.” You’re just another fucking plague rat.

I’m SciBabe, and this has been your daily Moment of Science.

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