Safety guideline for COVID19: Role of prevalence of infection  Summary and Q&A
TL;DR
Safety guidelines for controlling the spread of a pandemic should consider both the indoor reproductive number and the prevalence of infection in a given region.
Questions & Answers
Q: What is the significance of considering the prevalence of infection in safety guidelines?
Considering the prevalence of infection helps determine the appropriate level of restrictions in a given region. As the number of infected individuals in the population increases, stricter measures should be implemented to control the spread of the disease.
Q: How is the transmission rate calculated in the model?
The transmission rate is calculated by multiplying the number of infected individuals (I) by the number of susceptible individuals (S) in the room. This rate is influenced by the prevalence of infection (pI) and the probability of transmission (TMN).
Q: What assumptions are made in the model for random transmissions?
The model assumes that the transmission events are independent and identically distributed Poisson processes. It neglects any correlations between the infected individuals and assumes that the number of infected people and transmission events are uncorrelated.
Q: How is the expected number of transmissions calculated?
The expected number of transmissions is calculated by multiplying the total number of pairs of infected and susceptible individuals (IS) by the expected value of the transmission time (tau MN). This can be further simplified using the average transmission rate (beta bar) and the physical parameters of the room.
Summary & Key Takeaways

Safety guidelines have traditionally been based on the indoor reproductive number, which measures the effective number of new infections from a single infected person in a room.

The prevalence of infection in a region should also be taken into account when determining safety restrictions.

A simple model based on random transmissions and the number of infected and susceptible individuals helps calculate the expected number of transmissions in a room.