“The basic reproductive number, R₀, is widely used in infectious disease research to estimate the transmission potential of a disease. R₀ is defined as the average number of secondary infections caused by a single infection, assuming that the population is completely susceptible and that there are no interventions. Generally, a disease with an R₀ value < 1 will eventually die out, while a disease with an R₀ value > 1 may continue to spread and trigger an epidemic. Average R₀ values for some common infectious diseases are listed in Table 1. In its simplest form,

Equation 1
R₀ = pcd
where p is the transmissibility of the disease, c is the rate of contact with uninfected members of the population, and d is the duration of contagiousness. In reality, a population may not be entirely susceptible and interventions may provide immunity to certain members of the population. Thus, the effective reproductive number, R, is a means of relating R₀ to the actual level of susceptibility and is given by

Equation 2
R = R₀x
where x is the proportion of the population which is susceptible. One highly successful method of combating an outbreak is vaccination. The proportion of the population, V, which would need to be vaccinated in order to reduce the effective reproductive number to < 1 is

Equation 3
V = 1 – (1/ R₀)
Estimates of R₀, R, and V are used to determine the appropriate level of intervention necessary to control infectious diseases.

 

Disease	R0
Measles	16
Diphtheria	7
Smallpox	6
Polio	6
Mumps	5
HIV	4
SARS	4
Ebola	3
Influenza (1918)	2

Table 1. Approximate R₀ values for common diseases.”.

---

Find an error? Take a screenshot, email it to us at error@mytestingsolution.com, and we’ll send you $3!