Mathematical Modelling Long-Term Effects of Replacing Prevnar7 with Prevnar13 on Invasive Pneumococcal Diseases in England and Wales
Authored by Yoon Hong Choi, Mark Jit, Stefan Flasche, Nigel Gay, Elizabeth Miller
Date Published: 2012
DOI: 10.1371/journal.pone.0039927
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Abstract
Introduction: England and Wales recently replaced the 7-valent
pneumococcal conjugate vaccine (PCV7) with its 13-valent equivalent
(PCV13), partly based on projections from mathematical models of the
long-term impact of such a switch compared to ceasing pneumococcal
conjugate vaccination altogether.
Methods: A compartmental deterministic model was used to estimate
parameters governing transmission of infection and competition between
different groups of pneumococcal serotypes prior to the introduction of
PCV13. The best-fitting parameters were used in an individual based
model to describe pneumococcal transmission dynamics and effects of
various options for the vaccination programme change in England and
Wales. A number of scenarios were conducted using (i) different
assumptions about the number of invasive pneumococcal disease cases
adjusted for the increasing trend in disease incidence prior to PCV7
introduction in England and Wales, and (ii) a range of values
representing serotype replacement induced by vaccination of the
additional six serotypes in PCV13.
Results: Most of the scenarios considered suggest that ceasing
pneumococcal conjugate vaccine use would cause an increase in invasive
pneumococcal disease incidence, while replacing PCV7 with PCV13 would
cause an overall decrease. However, the size of this reduction largely
depends on the level of competition induced by the additional serotypes
in PCV13. The model estimates that over 20 years of PCV13 vaccination, around 5000-62000 IPD cases could be prevented compared to stopping
pneumococcal conjugate vaccination altogether.
Conclusion: Despite inevitable uncertainty around serotype replacement
effects following introduction of PCV13, the model suggests a reduction
in overall invasive pneumococcal disease incidence in all cases. Our
results provide useful evidence on the benefits of PCV13 to countries
replacing or considering replacing PCV7 with PCV13, as well as data that
can be used to evaluate the cost-effectiveness of such a switch.
Tags
Children
Impact
Carriage
Conjugate vaccine
Streptococcus-pneumoniae
Serotype replacement