Pulse vaccination strategy

File:Pulse Polio Day, Gwalior, January 2014.jpg

On Pulse Polio Day, a child swallows vaccine drops and is marked as vaccinated (felt-nib pen on finger). The Pulse Polio immunisation campaign eliminated polio from India.

The pulse vaccination strategy is a method used to eradicate an epidemic by repeatedly vaccinating a group at risk, over a defined age range, until the spread of the pathogen has been stopped. It is most commonly used during measles and polio epidemics to quickly stop the spread and contain the outbreak.

Where T= time units is a constant fraction p of susceptible subjects vaccinated in a relatively short time. This yields the differential equations for the susceptible and vaccinated subjects as:

$\frac{dS}{dt} = \mu N - \mu S - \beta \frac{I}{N} S, S(n T^+) = (1-p) S(n T^-) n=0,1,2,\dots$

$\frac{dV}{dt} = - \mu V, V(n T^+) = V(n T^-) + p S(n T^-) n=0,1,2,\dots$

It is easy to see that by setting I = 0 one obtains that the dynamics of the susceptible subjects is given by:

$S^*(t) = 1- \frac{p}{1-(1-p)E^{-\mu T}}E^{-\mu MOD(t,T)}$

and that the eradication condition is:

$R_0 \int_{0}^{T}{S^*(t)dt} < 1$

See also

• Critical community size
• Epidemic model
• Pulse Polio
• Vaccine-naive
• Herd immunity
• Ring vaccination

External links

• Immunisation Immunisation schedule for children in the UK. Published by the UK Department of Health.
• CDC.gov - 'National Immunization Program: leading the way to healthy lives', US Centers for Disease Control (CDC information on vaccinations)
• CDC.gov - Vaccines timeline
• History of Vaccines Medical education site from the College of Physicians of Philadelphia, the oldest medical professional society in the US
• Images of vaccine-preventable diseases