Graduation Year

2019

Document Type

Thesis

Degree

M.S.P.H.

Degree Name

MS in Public Health (M.S.P.H.)

Degree Granting Department

Epidemiology and Biostatistics

Major Professor

Aurora Sanchez-Anguiano, M.D., Ph.D.

Committee Member

Kevin E. Kip, Ph.D. FAHA

Committee Member

Getachew A. Dagne, Ph.D.

Keywords

Influenza, Vaccine, Selective Pressure, Epidemiology

Abstract

Understanding the evolutionary dynamics of influenza type B in human hosts is a public health concern as we strive to minimize the disease burden in seasonal epidemics. Vaccination is considered the best defense against contracting influenza, and everyone over the age of 6 months is advised to get vaccinated before each season. The effect that vaccine-acquired immunity has on the evolution of influenza B remains unclear. In the U.S., vaccine-uptake is irregular across the states, and the differing coverages present an opportunity to study how vaccination influences viral evolution. This thesis analyzes the evolutionary patterns of influenza B in the presence of vaccine-induced selective pressure. Using an ecological study design, estimates on statewide vaccination coverages from the Centers for Disease Control and Prevention were related to influenza B sequence data. The phylogenies and the frequencies of single nucleotide polymorphisms for high and low coverage states across three influenza seasons were compared to evaluate if there was evidence of vaccination influencing evolution. Overall, the results show that vaccination does not significantly impact the evolutionary dynamics of influenza B with both high and low coverage states showing interspersed phylogenetic trees and similar antigenic diversities.

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