Scott Alexander summarizes and responds to reader comments on his 'Diseasonality' article, exploring various aspects of disease seasonality across different viruses and geographical locations. Longer summary

This post discusses highlights from reader comments on the 'Diseasonality' article. It covers several key points: 1) A paper on SARS-CoV-2 transmission dynamics that explains seasonal patterns of coronaviruses, 2) Insights on how COVID-19 might become a seasonal endemic virus, 3) Discussions on the seasonality of other diseases like chickenpox and flu, 4) Comparisons between disease management and wildfire management, 5) The unique summer seasonality of polio, and 6) A simulation supporting the broad conditions for disease seasonality. The post synthesizes these reader contributions to further explore the concept of disease seasonality introduced in the original article. Shorter summary

Scott Alexander examines theories for disease seasonality, proposing a dynamic model where seasonal factors entrain waning immunity cycles. Longer summary

Scott Alexander explores the seasonality of diseases, particularly focusing on flu and COVID-19. He discusses various theories for why diseases peak in winter, including cold temperatures, low humidity, indoor crowding, and vitamin D deficiency. He finds these explanations unsatisfactory and proposes that ultraviolet light might play a role. Scott then considers a dynamic model where disease immunity wanes over time, and seasonal factors entrain this cycle to create annual epidemics. He suggests that COVID-19 is currently in a 'half-seasonal' phase and may become fully seasonal once it has infected most of the population and exhausted easy mutations. Shorter summary