Protected for Life
Our immune system remembers pathogens for an amazingly long time. How does this work and what does it mean in terms of Covid-19 vaccines?
Like our brain, our body's defenses can recall past experiences. In principle, this works in a similar way for both – we live through an event and store the memory of it in a memory from which it can be recalled later. However, you have to have survived the event first.
Before there were vaccinations against pathogens, acquiring immune memory was a dangerous proposition. It was by no means always possible to survive the encounter with the respective pathogen or the disease it triggered. In the event of recovery, the patients had retained a resilience comparable to a scar left by an injury. In contrast, the vaccines available today provide a much safer shield against potentially deadly microorganisms. They allow our body's defenses to remember foreign invaders without ever having been at risk of natural infection.
For a long time, however, immune memory has been a mystery. Almost all cells in the body eventually die and are replaced by new ones. In the case of lymphocytes, for example, important blood cells in the immune system, the life span is sometimes just days to weeks. How can our body's defenses then remember encounters with germs for 50 years or even longer? …