Acquired Immune Responses Varies Substantially
When innate immunity, the initial defense against infection, is working properly — as it does in most people infected with Sars-Cov-2 who develop mild or no symptoms of disease — the second stage, adaptive immunity, kicks in after a few days. Warning: even mild Covid-19 infections can make people sick for months. [14] Figure 1. Innate immunity vs Adaptive immunity Adaptive response The nature of acquired immune responses following natural infection varies substantially among pathogens: [11] Measles (1) or smallpox (2) virus Results in lifelong protection from the re-acquisition and re-transmission of secondary infections Influenza (3), respiratory syncytial virus (RSV) (4) Confer imperfect or transient clinical and transmission-blocking immunity either via pathogen evolution or waning immunological memory Dengue (5) or a vaccine (e.g., RSV (6)) Could result in more clinically severe secondary infections due to a phenomena known as antibody-depend...