Herd immunity

If enough people in a given population are individually protected from a certain infection, everyone benefits. Basically, a microbe cannot circulate in enough hosts if those potential hosts are immune. So the microbe doesn’t circulate, or at least not as much. That’s good for people without any individual protection. The herd shelters them.

Unfortunately, in the early days of COVID-19, none of us has much sanctuary. The herd is actually unsafe. Consequently, we spend a lot of time alone, separated, wary of each other, surfaces we’ve touched, even the air we’ve commonly breathed.

Earlier this week, while hiking in the forest not too far from my house, a very friendly dog bounded toward me. “She likes to lick,” the owner called. I stood still, hands in my pocket. The dog gave me the “Come on, I know you want to pet me” look, then gave up with a shrug when I didn’t reach out and comply.

Antibodies. We all wish we had them. Because antibodies, of the right kind and in sufficient quantities, means personal safety, security. Individual immunity. The chance to pet people’s dogs and not shrink away from dogs’ owners when we are all out in public.

Human immune systems are pretty complex. There are lots of parts and each part has subparts, with those subparts containing layers of componentry. Some cells are fighters. Others are helpers. The further one goes into the study of it all the more technical the names become. Most have numbers, almost as if scientists gave up trying to name everything discovered in a human host designed to stave off external invaders, large and small. Numbers and wordless letters also maintain a certain neutrality; the soldiers within our immune systems can sometimes get hyper-excited and attack native tissue by mistake. “Auto-immunity” is not a fun thing to experience, to which many people who suffer from various illnesses can attest.

Walking in the forest following my recent close encounter with a friendly four-legged standard poodle, it occurred to me that there may be more to the concept of “herd immunity” than we’ve envisioned. The public health advantage is clear; non-immune individuals benefit from the immunity of others. But suppose we play roles in the common immunologic landscape other than independent physical forms teeming with internal serologic security staff? Suppose we ourselves are walking and talking parts of the planet’s immune system?

We are more than a species, co-existing on a planet teetering on the edge of disarray. We are a collection of individual constituent pieces. And we each have parts to play.

Some of us are like B and T lymphocytes; we carry broad memories of past assaults on ecosystems and life forms, ready to identify trends and communicate threats. Others are NK or natural killer cells; we serve as emergency responders. There are the cleaners and waste removers (the “lymphaticists”), the filterers and producers (our “bone marrowists”, “thymusists”, and “splenics”), the supporters (our “helper cells”) and then a whole host of specialists: people perhaps like you and me who have targeted abilities to perform key functions in the world, people who think we don’t make much of a difference until a need arises that we are personally and uniquely qualified and able to recognize and address, people who depend on each other for our common survival and who, without the ability to rely on that interdependence, would not individually survive.

We are, many of us, our species’ – and our world’s – antibodies.

Think about that, the next time you look at someone or some other living creature and you wonder about her or its place on this planet. We got here, to this point in time, together, as a gathering of species and possibilities, not because of our similarities but instead because of our differences. Sometimes we hurt each other; sadly, we have a proclivity for auto-immunity at a macroscopic level. Most of the time, however, we help and support each other at the micro level, in the small things we say and do, in the myriad of things that we sometimes refrain from saying and doing.

I regret that I did not feel safe to reach out and pet that poodle the other day. But the dog didn’t seem worried. It bounded off beyond me, secure in the awareness that there was a greeting still to come further down the trail. Somehow, it knew what my COVID-19 confounded consciousness caused me to forget: we are a herd.