An investigation of testing capacity for evaluating and modeling the spread of coronavirus disease

Abstract

Despite the consistent recommendation to scale-up the testing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), comprehensive analysis on determining the desirable testing capacity (TC) is limited. This study aims to investigate the daily TC and the percentage of positive cases over the tested population (PPCTP) to evaluate the novel coronavirus disease 2019 (COVID-19) trajectory phase and generate benchmarks on desirable TC. Data were retrieved from government facilities, including 101 countries and 55 areas in the USA. We have divided the pandemic situations of investigated areas into four phases, i.e., low-level, suppressing, widespread, or uncertain transmission phase. Findings indicate each country should increase TC to roughly two tests per thousand people each day. Additionally, based on TC, a susceptible-unconfirmed-confirmed-recovered (SUCR) model, which can capture the dynamic growth of confirmed cases and estimate the group size of unconfirmed cases in a country or area, is proposed. We examined our proposed SUCR model for 55 areas in the USA. Results show that the SUCR model can accurately capture the dynamic growth of confirmed cases in each area. By increasing TC by five times and applying strict control measures, the total number of COVID-19 patients would reduce to 33%.

Keywords: COVID-19; Epidemiological model; Pandemic evaluation; Testing capacity; Time series prediction.

Fig. 1

Pandemic situations of New York State, the UK, Pakistan, Chile, and Korea: (a) the number of daily COVID-19 tests per thousand people in a country or area, $\mathit{TC}\left(t\right)$; (b) the percentage of positive cases over the tested population $\mathit{PPCPT}\left(t\right)$; and (c) an overview of pandemic situations in terms of $\mathit{TC}\left(t\right)$ and $\mathit{PPCPT}\left(t\right)$.

Fig. 2

TC in different countries. The red dashed line represents the average TC of the 101 countries. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Classification of the pandemic situation of 101 countries in six continents on September 30, 2020.

Fig. 4

Results of daily TC against PPCTP (Squares represent the mean values, while the horizontal and vertical bars indicate the lower and upper bound of the 95% CI, respectively): (a) The mean values and 95% CI of TC and PPCTP of countries in six different continents; (b) The mean values and 95% CI of TC and PPCTP of countries in four different situations; (c) The mean values and 95% CI of TC and PPCTP of countries in developed, developing, and undeveloped countries.

Fig. 5

The average TC of 55 areas in the USA from Feb 27, 2020 to September 30, 2020.

Fig. 6

Classification of the pandemic situation of 55 areas in the USA on September 30, 2020.

Fig. 7

Results of daily TC against PPCTP (Squares represent the mean values, while the horizontal and vertical bars indicate the lower and upper bound of the 95% CI, respectively): (a) The mean values and 95% CIs of TC and PPCTP of 55 states in the four different situations; (b) The mean values and 95% CIs of TC and PPCTP of states, of which the governor belongs to the Democratic Party or the Republican Party.

Fig. 8

Estimated historical data of the number of confirmed cases, unconfirmed cases, and total infected cases in four selected states (including Iowa, New Jersey, Minnesota, and New York) in the USA. (a), (d), (g), and (j) show the number of active confirmed cases in each state, in which the squares indicate the real number of confirmed cases, while the three solid lines represent the estimated active number of confirmed cases in three different scenarios: scenario I, scenario II, and scenario III. (b), (e), (h), and (k) show the number of cumulative confirmed cases of the three different scenarios. (c), (f), (i), and (l) show the cumulative of confirmed and unconfirmed cases.

Fig. 9

Number of infected cases in different areas in the USA: (a) The number of confirmed cases (blue bar) and unconfirmed cases in each state in scenario I; (b) the number of confirmed cases (blue bar) and unconfirmed cases in each state under the condition of increasing TC by five times (scenario II); (c) the number of confirmed cases (blue bar) and unconfirmed cases in each state under the condition of increasing TC by five times and applying strict isolation measures (scenario III). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)