Vaccine boosts innate immunity in people with dormant immune cells

Humans are protected by two branches of the immune system. Innate immunity provides built-in defense against widespread characteristics of bacteria and viruses, while adaptive immunity memorizes individual pathogens that a person has already encountered. Vaccines teach the adaptive immune system about new pathogens without having to go through an actual infection. This has greatly contributed to human health, but requires a specific vaccine for each major pathogen. Some vaccines not only teach the adaptive immune system about a specific pathogen, but also increase the overall vigilance of our body’s innate immune cells. The BCG vaccine, which teaches our adaptive immune system to fight tuberculosis bacteria, has been shown to reduce infant mortality independent of its protection against tuberculosis. This observation can be explained by the concept of “trained immunity” – the idea that innate immune cells can switch between dormant and vigilant states, and are more effective at fighting infection when...