The article discusses the concept of herd immunity in the context of COVID-19, emphasizing its importance and implications. Herd immunity is defined as indirect protection from infection when a sufficient proportion of the population is immune. The authors explain that this effect is achieved through individual immunity, either from natural infection or vaccination, and it depends on the basic reproduction number (R0) and the effective reproduction number (Re). They highlight that the herd immunity threshold, which is 1 − 1/R0, varies across populations due to factors such as population density, structure, and contact rates. The article also explores the challenges of achieving herd immunity, including the potential for heterogeneity in infectivity and the duration of immunity. The authors conclude that while herd immunity is a theoretical possibility, the ethical and practical consequences of widespread infection are severe, and the focus should be on protecting vulnerable groups and developing effective vaccines.The article discusses the concept of herd immunity in the context of COVID-19, emphasizing its importance and implications. Herd immunity is defined as indirect protection from infection when a sufficient proportion of the population is immune. The authors explain that this effect is achieved through individual immunity, either from natural infection or vaccination, and it depends on the basic reproduction number (R0) and the effective reproduction number (Re). They highlight that the herd immunity threshold, which is 1 − 1/R0, varies across populations due to factors such as population density, structure, and contact rates. The article also explores the challenges of achieving herd immunity, including the potential for heterogeneity in infectivity and the duration of immunity. The authors conclude that while herd immunity is a theoretical possibility, the ethical and practical consequences of widespread infection are severe, and the focus should be on protecting vulnerable groups and developing effective vaccines.