Since newborn babies haven’t encountered many pathogens, they haven’t yet built up a fully robust immune response. But they do have what’s known as “innate immunity” — a collection of bacteria-busting molecules and cells we’re all born with, such as neutrophils and macrophages.
More recently, scientists have come to appreciate another member of the innate immune system: platelets. Better known for their role in clotting blood, it turns out platelets also help keep the bloodstream clear of bacteria. For example, platelets can directly kill Staphylococcus aureus (staph bacteria), a common but sometimes life-threatening microbe.