At the beginning of June, it’s time: I received my first dose of the Sars-CoV-2 vaccine. The dull ache in my arm and fatigue the next day showed my immune system was reacting as intended. But what exactly happens in our bodies during this vaccination? Above all: how can vaccines cause immunity to a pathogen, often decades of life, when most of the body’s cells are fairly short-lived?
Mark Hellerstein of the University of California, Berkeley, explores such questions in this issue’s cover story beginning on page 12. He developed new methodological approaches to learning how our immune system’s memory develops after encountering germs. Because this plays a major role in future long-term protection against disease. Normally, lymphocytes, which are essential for immune defense, only live for a few days or weeks. Do they pass on information about the pathogen to subsequent cells after infection or vaccination before they bless time? But it is also conceivable that the cellular transporters of immune memory are simply extraordinarily persistent. In one of the experiments, the author was able to establish that some of the specially reactive immune cells that formed after vaccination against yellow fever are actually still present in the body after several years. Other than that, longevity is only known from neurons in the brain – by the way, the only other system in the body that has memory as well.
In addition to insight into the miracle of our bodies’ defenses, Hellerstein’s article outlines the success story of vaccines – perhaps the greatest achievement in medicine and comparable in importance to technological advances such as electricity or the Internet. It is easy to forget what kind of suffering polio, diphtheria or smallpox caused in the past. According to estimates, about 300 million people died from the latter alone in the twentieth century. Thanks to vaccinations, these epidemics have lost their horrors.