R 0 = 1.55. The basic reproduction numbers of the COVID-19 pandemic were
estimated in [12–14, 22, 30]. According to WHO calculations for China [12],
values R 0 vary from 2 to 2.5.
Figure 6.22 illustrate that the number of cases registered in USA before March 1,
2020 (V j , “triangles”) was significantly less than the theoretical estimate
V = I + R (solid line). For almost two months, the COVID-19 epidemic remained
unnoticed in this country. This conclusion is in good agreement with the results of a
very interesting study [88]. A fundamental statistical analysis showed that the
number of cases of pneumonia in the USA in January and February 2020 exceeded
previous year’s figures and this excess was higher in those states where the actual
numbers of reported COVID-19 cases are larger [88].
Figure 6.23 illustrates that the number of cases registered in USA (V j , “stars”)
started to deviate significantly from the theoretical V = I + R curve (solid line) in
10–15 days after T c . The result of this behavior is the very large value of the
relative error e. Usually, the accuracy of predictions can be improved with the use
of fresher data sets, but the character of the increase in the number of cases V j
demonstrates that next waves of the epidemic occurred. It means that classical SIR
theory (presented in Chap. 4) and the identification of its parameters (proposed in
Chap. 5 and used in this chapter to calculate SIR curves) does not work in the case
of USA statistics. Later, we will discuss how the new waves of the pandemic can be
simulated with the use of generalized SIR model.
A comparison of the epidemic dynamics in USA with the pandemic situation in
other countries and in the world is shown in Figs. 6.6 and 6.7. The SIR curves and
markers representing the V j values taken for calculations (“circles”), comparisons
(“triangles”) and verifications of calculations (“stars”) are shown by blue color for
USA. Figure 6.6 demonstrates that the first COVID-19 cases in the USA probably
occurred at the same time as in Italy (compare blue and green lines). Before March
1, 2020, the estimated numbers of cases in Italy and USA were rather close.
Nevertheless, on March 1 the number of confirmed cases in Italy was 1689 in
comparison with 62 in USA. This delay with detection of infected persons and later
quarantining (see, e.g., [87]; in particular, in New York the quarantine was
announced on March 20, in comparison with March 8 in Lombardy and March 10
in Italy) caused the huge difference in number of cases (visible in Fig. 6.7).
Figure 6.6 shows that in the Republic of Korea the detected number of cases was
close to the estimated one (compare solid magenta line and magenta “triangles”)
already on March 1. Timely testing and isolation of patients allowed this country to
avoid a large number of cases (visible in Fig. 6.7).
6.10 The Republic of Moldova
In this section, we consider the first wave of the COVID-19 epidemic in the
Republic of Moldova and present the results of two SIR simulations.
72
6 SIR Simulations for the First Waves of the COVID-19 …
estimated in [12–14, 22, 30]. According to WHO calculations for China [12],
values R 0 vary from 2 to 2.5.
Figure 6.22 illustrate that the number of cases registered in USA before March 1,
2020 (V j , “triangles”) was significantly less than the theoretical estimate
V = I + R (solid line). For almost two months, the COVID-19 epidemic remained
unnoticed in this country. This conclusion is in good agreement with the results of a
very interesting study [88]. A fundamental statistical analysis showed that the
number of cases of pneumonia in the USA in January and February 2020 exceeded
previous year’s figures and this excess was higher in those states where the actual
numbers of reported COVID-19 cases are larger [88].
Figure 6.23 illustrates that the number of cases registered in USA (V j , “stars”)
started to deviate significantly from the theoretical V = I + R curve (solid line) in
10–15 days after T c . The result of this behavior is the very large value of the
relative error e. Usually, the accuracy of predictions can be improved with the use
of fresher data sets, but the character of the increase in the number of cases V j
demonstrates that next waves of the epidemic occurred. It means that classical SIR
theory (presented in Chap. 4) and the identification of its parameters (proposed in
Chap. 5 and used in this chapter to calculate SIR curves) does not work in the case
of USA statistics. Later, we will discuss how the new waves of the pandemic can be
simulated with the use of generalized SIR model.
A comparison of the epidemic dynamics in USA with the pandemic situation in
other countries and in the world is shown in Figs. 6.6 and 6.7. The SIR curves and
markers representing the V j values taken for calculations (“circles”), comparisons
(“triangles”) and verifications of calculations (“stars”) are shown by blue color for
USA. Figure 6.6 demonstrates that the first COVID-19 cases in the USA probably
occurred at the same time as in Italy (compare blue and green lines). Before March
1, 2020, the estimated numbers of cases in Italy and USA were rather close.
Nevertheless, on March 1 the number of confirmed cases in Italy was 1689 in
comparison with 62 in USA. This delay with detection of infected persons and later
quarantining (see, e.g., [87]; in particular, in New York the quarantine was
announced on March 20, in comparison with March 8 in Lombardy and March 10
in Italy) caused the huge difference in number of cases (visible in Fig. 6.7).
Figure 6.6 shows that in the Republic of Korea the detected number of cases was
close to the estimated one (compare solid magenta line and magenta “triangles”)
already on March 1. Timely testing and isolation of patients allowed this country to
avoid a large number of cases (visible in Fig. 6.7).
6.10 The Republic of Moldova
In this section, we consider the first wave of the COVID-19 epidemic in the
Republic of Moldova and present the results of two SIR simulations.
72
6 SIR Simulations for the First Waves of the COVID-19 …