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Impact of waning immunity against SARS-CoV-2 severity exacerbated by vaccine hesitancy
Fig 2
Dynamics of different durations of natural and vaccinal severity protection, with variable vaccination rates, for different strengths of immunity.
(A), (B), (C), and (D) have vaccination rates ν = 0.0025 per week, ν = 0.01 per week, ν = 0.02 per week, and ν = 0.04 per week, respectively. In all panels, we assume that 
years and that 
years. For each column, we assume that the duration of severity-blocking immunity imparted from vaccination or infection is the same and is equal to the columnar label ℓc, i.e. 
and 
. Thus, 
years and 
years. In each panel, the top, middle, and bottom rows depict the fraction of individuals in Iw, the fraction of infections that are in Iw (i.e. 
, where 
), and the relative change in 
for each ε compared to ε = 1, i.e. 
, respectively (for weeks when f1(t) > 0). Other parameters are 
week−1 and μ = 0.02 years−1, as in previous work [6, 20–22]. The initial conditions here and throughout are a fraction 10−9 of individuals with primary infection (IP) and the remainder fully susceptible (SP), which is as in previous work with the simpler model [6].
doi: https://doi.org/10.1371/journal.pcbi.1012211.g002