Fig 1.
Statistics for COVID-19 pre-vaccination data in the U.S from January 21th, 2020 to February 1st, 2021.
Note that values have been scaled in order to allow comparisons in one figure.
Fig 2.
Infectious cases at time t − 1 who have been infected d days, i(t − 1, d), have three possible outcomes at time t.
An infectious case is either cured, they die, or they remain infectious, with rates cd, md, and 1 − cd − md, respectively.
Fig 3.
(A) Contact rate calculated as the fraction of new infected on day t in the total infected during day t − 29 through day t and set to 0.2 for the first 30 days. (B) Reproduction number R0(t) assuming data driven contact rate for exponential model (classical SIR model) and lognormal model where CFR is 8.5% for the first wave and 1.7% thereafter.
Fig 4.
COVID-19 analysis of pre-vaccination data using exponential model (classical SIR model) and lognormal model assuming CFR is 8.5% for the first wave and 1.7% thereafter.
(A,B) Probability and hazard values for cure and death for exponential model. (C) Estimated aCFR, cumulative and daily infected cases using exponential model compared to observed values. (D,E) Probability and hazard values for cure and death for lognormal model. (F) Estimated aCFR, cumulative and daily infected cases using lognormal model compared to observed values.
Fig 5.
What-if practical identifiability analysis of SICD lognormal model.
Estimated values for daily infected and deaths are given by for different and Mdeath values (i.e. what if
equals this and what if Mdeath equals this): (A)
(B) Mdeath = 0.85%, 1.7% and 3.4%.
Fig 6.
(A) Graphical representation of SIVCDI model. Removed status includes cured, dead, and immune from vaccination. (B) Contact rate and percentage of vaccinated population. Contact rate shows presence of a small wave after February 2021, which could be a potential fourth wave, but because of the success of vaccination, the fourth wave contact rate is much lower than the third wave contact rate. (C) Results of the data driven SIVCDI model from December 20th, 2020 to May 11th, 2021, where dashed lines are predicted values and solid lines are observed values.