Reproductive number of rabies among dogs in Kenya is 2.44 (Kitala et al, 2002)

Ro = 2.44

Generate sequence of numbers for fraction of population vaccinated from 0 to 1 with 0.1 interval

fraction_vaccinated = seq (0, 1, 0.1)

Print fraction of population vaccinated.

cat ("Fraction of population vaccinated: ", fraction_vaccinated)
## Fraction of population vaccinated:  0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Compute effective reproductive number

Re = Ro * (1 - fraction_vaccinated)

Print effective reproductive number

cat ("Effective reproductive number:", Re)
## Effective reproductive number: 2.44 2.196 1.952 1.708 1.464 1.22 0.976 0.732 0.488 0.244 0

Compute herd immunity threshold

herd_immunity_threshold = 1 - (1/Ro)

Print herd immunity threshold

cat ("herd immunity threshold = ", herd_immunity_threshold)
## herd immunity threshold =  0.5901639

Plot fraction of population vaccinated (versus) effective reproductive number

subtitle = paste ("Ro = ", Ro, ", herd immunity threshold = ", round (herd_immunity_threshold, digits = 4), "; dogs (Kenya) - Kitala et al (2002)", sep="")
plot (fraction_vaccinated, Re, main = "Rabies" , sub = subtitle, xlab = "Fraction of Population Vaccinated \n", ylab = "Effective Reproductive Number (Re)")

Results and Discussion

Reproductive number of rabies among dogs in Kenya is 2.44 (Kitala et al, 2002). The graph illustrates that as fraction of population vaccinated increases, effective reproductive number decreases. Herd immunity threshold is 59.02%; that is, at this level of vaccination coverage, effective reproductive number is 1 (Re = 1). When vaccination coverage is above 59.02%, effective reproductive number is less than 1 (Re < 1); thereby, rabies will be eliminated at these higher levels of vaccination coverage

Public heath implications

Recommend rabies vaccination among dogs in Kenya at coverage levels of above 59.02%