Edastatavuse

Edastatavus, or transmissibility, is the capacity of an infectious agent to be transmitted from one host to another, potentially leading to onward spread within a population. It can also be used in a broader sense to describe how readily information, ideas or signals propagate through a system, but in scientific contexts it is primarily used for pathogens.

In epidemiology, transmissibility is determined by a combination of pathogen properties, host characteristics and environmental and social factors. Biological factors include how long an individual remains infectious, how easily the pathogen is shed, its viability outside the host, and the infectious dose required to establish infection. Host factors include immunity, age, behavior and contact patterns. Environmental conditions such as humidity, temperature, and ventilation can influence transmission, as can cultural and behavioral practices that affect contact rates.

Transmissibility is commonly quantified through metrics like the basic reproduction number R0, which estimates the average number of secondary infections produced by a typical case in a fully susceptible population, and the effective reproduction number Re, which accounts for immunity and interventions. Other measures include the secondary attack rate and the probability of transmission per contact. It is important to note that transmissibility is context-dependent and can vary across populations, pathogens, and time.

Understanding transmissibility informs public health responses, including vaccination strategies, hygiene interventions, masking, ventilation improvements, and social measures designed to reduce contact rates. However, these estimates carry uncertainty and depend on data quality and model assumptions.