Strong correlations between power-law growth of COVID-19 in four continents and the inefficiency of soft quarantine strategies

Abstract

In this work, we analyze the growth of the cumulative number of confirmed infected cases by a novel coronavirus (COVID-19) until March 27, 2020, from countries of Asia, Europe, North America, and South America. Our results show that (i) power-law growth is observed in all countries; (ii) by using the distance correlation, the power-law curves between countries are statistically highly correlated, suggesting the universality of such curves around the world; and (iii) soft quarantine strategies are inefficient to flatten the growth curves. Furthermore, we present a model and strategies that allow the government to reach the flattening of the power-law curves. We found that besides the social distancing of individuals, of well known relevance, the strategy of identifying and isolating infected individuals in a large daily rate can help to flatten the power-laws. These are the essential strategies followed in the Republic of Korea. The high correlation between the power-law curves of different countries strongly indicates that the government containment measures can be applied with success around the whole world. These measures are scathing and to be applied as soon as possible.

FIG. 1.

Cumulative number of confirmed infected cases by COVID-19 as a function of time for (a) USA, (b) Germany, (c) Spain, (d) France, (e) Italy, (f) China, (g) Brazil, (h) Japan, and (i) Republic of Korea, excluding days with $<$100 infected cases. The black-continuous curves represent the function $\alpha +\beta t^{\mu }$ that fit the time-series, and the parameters $\alpha$, $\beta$, and $\mu$ for each country are described in Table I.

FIG. 2.

In panels (a), (b), (c), (g), (h), and (i) the log–log plot of the cumulative numbers of confirmed infected cases as a function of time is presented for the possible pairs of countries formed between Brazil, Italy, Japan, and USA. The semi-log plot of DC calculated between these pairs of countries is presented in panels (d), (e), (f), (j), (k), and (l), respectively.

FIG. 3.

Log–log plot of cumulative number of confirmed cases (black circles) for Italy [(a) and (c)] and France [(b) and (d)] as a function of time and projected number of cases (colored lines) using distinct government strategies (discussed in the text).

FIG. 4.

Log–log plot of cumulative number of confirmed cases (black circles) for Brazil [(a) and (c)] and USA [(b) and (d)] as a function of time and the projected number of cases (colored lines) using distinct government strategies (discussed in the text).