By David Bell at Brownstone dot org.

The primary reason people in wealthy countries live longer than those in poorer countries is that they have better sanitation (e.g. clean water, hygiene), nutrition (especially fresh food), living conditions (e.g. housing), and access to basic healthcare - like antibiotics for childhood pneumonia. This should be uncontroversial - it was taught in medical schools a few decades ago when evidence formed the basis of medicine.

The fact that it is now widely forgotten, or ignored as a matter of convenience, explains why there is such a fuss over the United States administration defunding Gavi - the 'Vaccine Alliance' based in Switzerland.

Our Age-Old Argument with Pathogens

As most public health people seem unaware, and many of the public also, let us review why so many of us now reach old age. Humans are constantly exposed to microbes that could cause harm. The vast majority don't, as our forebears spent hundreds of millions of years evolving defenses against them, even as the microbes evolved new ways to use our bodies to multiply their own.

Mostly, we live in harmony with bacteria - our gut is full of them, but they also cohabit in our bloodstream and elsewhere - even possibly in our brain, as that is demonstrated in other vertebrates. Most of the cells we lug around are actually not us, but bacteria that live with us.

Some microbes (bacteria, viruses, fungi, protozoa) and even small worms of various sorts can, however, cause us great harm (they become pathogens). Their genetic code is, like ours, designed to reproduce itself, and to do this they need to eat part of us or hijack the metabolism of our cells. In doing so, they can sicken or kill us.

We have evolved very effective ways to prevent this, by developing skin and mucosal barriers that hamper them from entering our bodies, and producing cells that eat or otherwise destroy them (our immune system). The brilliance of our immune system is that it has a memory. Once it has developed an effective chemical or cellular response to a pathogen, it stores that code so that an effective response can be very rapidly reactivated if the same pathogen comes along in the future.

Some pathogens frequently change their chemistry to try to get around this and still reproduce within us, and our immune response has to keep adjusting.

The Growth of Human Resilience

So, back to sanitation, nutrition, and living conditions. Relatively recently, we figured out what pathogens are (bacteria, viruses, protozoa, nematode worms, and the like) and better understood how to avoid them altogether. Many of the pathogens that used to kill us spread from person to person through a 'fecal-oral' route, as it is euphemistically called. They reproduce within the body, and the resulting multitude move on when we defecate.

If someone then drinks water contaminated by that, they get infected. Cholera, typhoid, and E. coli are well-known examples. Beyond aesthetics, this is why we have sewerage systems in towns and cities. We stopped most deaths from these simply by drinking clean water untainted by someone else's toilet.

Pathogens that spread by respiratory routes to cause disease (e.g. influenza, Covid-19) are more likely to pass between people if they live in a confined space with poor air circulation. This raises the chance of breathing in air others have breathed out, and increases the number of organisms that infect us at once (i.e. infective dose or 'viral load'). A high infective dose makes it more likely that we get very sick before our immune system can mount an effective response.

Good nutrition is absolutely essential for us to mount an effective immune response, whether to an organism or a vaccine. The cells in the immune system have specific requirements, such as Vitamins D, K2, C, and E, and zinc and magnesium, and cannot function well without an adequate concentration of them. They can also be impaired in their function when our general metabolism is impaired,...