TY - JOUR
T1 - On the role of cross-immunity and vaccines on the survival of less fit flu-strains
AU - Nuño, M.
AU - Chowell, G.
AU - Wang, X.
AU - Castillo-Chavez, Carlos
N1 - Funding Information:
M. Nuño is partially funded by the Yerby Postdoctoral Fellowship and the National Institutes of Health Grant T32AI07358. G. Chowell is supported through a Director's Postdoctoral Fellowship from Los Alamos National Laboratory. This research was also partially supported through the visit of M. Nuño and C. Castillo-Chavez to the Statistical and Applied Mathematical Sciences Institute (SAMSI), Research Triangle Park, NC, which is funded by NSF under the Grant DMS-0112069. C. Castillo-Chavez and X. Wang were supported through NSF Grant (DMS-0441114), NSA Grant H98230-05-1-0097 and The Alfred P. Sloan Foundation Grant (016935-001).
PY - 2007/2
Y1 - 2007/2
N2 - A pathogen's route to survival involves various mechanisms including its ability to invade (host's susceptibility) and its reproductive success within an invaded host ("infectiousness"). The immunological history of an individual often plays an important role in reducing host susceptibility or it helps the host mount a faster immunological response de facto reducing infectiousness. The cross-immunity generated by prior infections to influenza A strains from the same subtype provide a significant example. The results of this paper are based on the analytical study of a two-strain epidemic model that incorporates host isolation (during primary infection) and cross-immunity to study the role of invasion mediated cross-immunity in a population where a precursor related strain (within the same subtype, i.e. H3N2, H1N1) has already become established. An uncertainty and sensitivity analysis is carried out on the ability of the invading strain to survive for given cross-immunity levels. Our findings indicate that it is possible to support coexistence even in the case when invading strains are "unfit", that is, when the basic reproduction number of the invading strain is less than one. However, such scenarios are possible only in the presence of isolation. That is, appropriate increments in isolation rates and weak cross-immunity can facilitate the survival of less fit strains. The development of "flu" vaccines that minimally enhance herd cross-immunity levels may, by increasing genotype diversity, help facilitate the generation and survival of novel strains.
AB - A pathogen's route to survival involves various mechanisms including its ability to invade (host's susceptibility) and its reproductive success within an invaded host ("infectiousness"). The immunological history of an individual often plays an important role in reducing host susceptibility or it helps the host mount a faster immunological response de facto reducing infectiousness. The cross-immunity generated by prior infections to influenza A strains from the same subtype provide a significant example. The results of this paper are based on the analytical study of a two-strain epidemic model that incorporates host isolation (during primary infection) and cross-immunity to study the role of invasion mediated cross-immunity in a population where a precursor related strain (within the same subtype, i.e. H3N2, H1N1) has already become established. An uncertainty and sensitivity analysis is carried out on the ability of the invading strain to survive for given cross-immunity levels. Our findings indicate that it is possible to support coexistence even in the case when invading strains are "unfit", that is, when the basic reproduction number of the invading strain is less than one. However, such scenarios are possible only in the presence of isolation. That is, appropriate increments in isolation rates and weak cross-immunity can facilitate the survival of less fit strains. The development of "flu" vaccines that minimally enhance herd cross-immunity levels may, by increasing genotype diversity, help facilitate the generation and survival of novel strains.
KW - Coexistence
KW - Cross-immunity
KW - Influenza
KW - Invasion reproduction number
KW - Isolation
KW - Sub-threshold coexistence
KW - Uncertainty and sensitivity analysis
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U2 - 10.1016/j.tpb.2006.07.002
DO - 10.1016/j.tpb.2006.07.002
M3 - Article
C2 - 16930653
AN - SCOPUS:33750968462
SN - 0040-5809
VL - 71
SP - 20
EP - 29
JO - Theoretical Population Biology
JF - Theoretical Population Biology
IS - 1
ER -