The Influence of Social Network Graph Structure on Disease Dynamics in a Simulated Environment Page: 69
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4.4.2. Graph Structure and Outbreak Analysis
The severity of every simulated outbreak is measured based upon the proportion of the popula-
tion that becomes infected, the value of R0, and the duration. These findings support similar results
presented in Chapter 3. The results are summarized in Tables 4.6, 4.7, and 4.8. Although there
are exceptions as noted in the tables, general trends are observed regarding each of the severity
measures as discussed below.
The proportion of the population that becomes infected during the simulations after implemen-
tation of a vaccination policy (see Table 4.6) ranges from 15.4% to 88.7%. The lowest average
occurs at N = 250 and p = 0 under the high contact vaccination policy. The highest average
occurs at N = 150 and p = 0.25 under the low contact vaccination policy. Consistent with ear-
lier experiments, the proportion of infected individuals increases with the number of non-local
contacts regardless of the vaccination policy. This is an indication that restricted contacts have a
tendency to confine the spread of an outbreak. Additionally, the proportion of infected individuals
is found to be considerably higher in smaller populations in simulations in which there are no, or
very few (p = 0 or p = 0.01) outside contacts. This disparity is not observed in simulations with
a larger probability of non-local contacts (p = 0.25 and p = 0.5). The neighborhood size, k = 6,
is held constant for these experiments regardless of the population size which may account for
this discrepancy. In smaller populations, the neighborhood size is proportionally larger, thereby
increasing the probability that the disease will transfer to a higher proportion of individuals in the
Average values of R0, as shown in Table 4.7 range from 2.65 to 4.07 in simulations with
vaccination implementation. The low value of 2.65 occurs at N = 50 and p = 0 under the
random vaccination policy. The highest average of 4.07 occurs at N = 50 and p = 0.5 under
the low contact vaccination policy. All vaccination strategies are shown to lower the value of Ro0.
Regardless of the population size or the type of vaccination, the value of R0 tends to increase
with the probability of outside contacts. The population size, N, does not appear to have as much
influence over R0 as the probability of non-local contacts and the vaccination method. Perhaps
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Johnson, Tina V. The Influence of Social Network Graph Structure on Disease Dynamics in a Simulated Environment, dissertation, December 2010; Denton, Texas. (https://digital.library.unt.edu/ark:/67531/metadc33173/m1/79/: accessed May 26, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; .