We consider a model for a disease with
two competing strains and vaccination.
The vaccine provides complete protection against one of the strains
(strain 2) but only
partial protection
against the other (strain 1). The partial protection leads to
existence of subthreshold equilibria of strain 1. If the first strain
mutates into the second, there are subthreshold coexistence equilibria
when both vaccine-dependent reproduction numbers are below one.
Thus, a vaccine that is specific toward the second strain
and that, in absence of other strains, should be able to eliminate
the second strain
by reducing its reproduction number below one,
cannot do so because it provides only
partial protection to another strain that mutates into the second strain.
Keywords:
- latent stage,
- coexistence,
- strongly
subthreshold coexistence,
- vaccine enhanced pathogen polymorphism.,
- multiple coexistence equilibria,
- multiple endemic equilibria,
- mutation,
- backward bifurcation,
- latent-stage progression age structure,
- alternating stability,
- vaccination
Citation: Maia Martcheva, Mimmo Iannelli, Xue-Zhi Li. Subthreshold coexistence of strains: the impact of vaccination and mutation[J]. Mathematical Biosciences and Engineering, 2007, 4(2): 287-317. doi: 10.3934/mbe.2007.4.287
Abstract
We consider a model for a disease with
two competing strains and vaccination.
The vaccine provides complete protection against one of the strains
(strain 2) but only
partial protection
against the other (strain 1). The partial protection leads to
existence of subthreshold equilibria of strain 1. If the first strain
mutates into the second, there are subthreshold coexistence equilibria
when both vaccine-dependent reproduction numbers are below one.
Thus, a vaccine that is specific toward the second strain
and that, in absence of other strains, should be able to eliminate
the second strain
by reducing its reproduction number below one,
cannot do so because it provides only
partial protection to another strain that mutates into the second strain.