calculated in the second prediction (see Table 6.25), the corresponding global
figure is R 0 = 1.99.
Unfortunately, we could correctly apply formula (4.20) only in February–March
2021 (after moments of time corresponding to t final ), but as early as September 26,
2020, the number of registered cases in the world 32,730,945 (see, e.g., [86])
already significantly exceeded theoretical estimates V 1 . In Table 6.25, we have
used the inequality V f > 32,730,945 to calculate the lower limit of possible values
of relative error. It can be seen that the accuracy of SIR simulations of the global
first wave (e will exceed 79–85%) is the lowest one (in contrast to the situation for
the EU countries, and even to USA, the UK, Ukraine, and the Republic of
Moldova). So, the second and subsequent global waves of the COVID-19 pandemic
began before the end of the first wave. We will discuss this in detail in the following
chapters.
The SIR curves corresponding to prediction 1 are shown in Figs. 6.6 and 6.7.
The epidemic dynamics in the world (brown lines and markers) was compared with
the situation in USA (blue), Italy (green), Spain (yellow), the UK (red), and South
Korea (magenta). The markers represent V j values taken for calculations (“circles”),
comparisons (“triangles”) and verifications of calculations (“stars”). The number of
laboratory confirmed cases in Wuhan, China, is shown by brown “squares.” These
values were calculated in [69] with the use of information from [6]. Solid brown
line and brown “triangles” in Fig. 6.6 illustrate a big difference between number of
calculated and actual cases which can be explained by the fact that many infected
people do not have symptoms and there were and still are problems with their
detection. In particular, the hidden periods (time between the estimated epidemic
beginning t
Ã
1 and the first confirmed case) can be rather long.
The value t
Ã
1 estimated in prediction 1 (the beginning of the epidemic in late
September 2019) does not look very reliable, since the registered number of global
cases V j was higher than the theoretical estimation V(t) in February 2020 (compare
brown “triangles” and brown solid line in Fig. 6.6). The above examples of SIR
simulations in different countries show the opposite picture. Therefore, the estimate
of the value of t
Ã
1 obtained in prediction 2 is more credible, because all values V j are
below the corresponding theoretical curve V(t) (see Fig. 6.29). The beginning of the
pandemic should be sought in early August 2019, and in Ukraine it probably began
in early 2020 (according to forecast 8, the results of which are also shown in
Figs. 6.29 and 6.30).
Dashed magenta curve in Fig. 6.29 illustrates that more than 2000 persons could
spread the infection on December 31, 2019—the day when China notified WHO
about the situation in Wuhan. On January 23, 2020, this city was locked down, but
the number of infected persons could be estimated by 6000 with hundreds of cases
in USA, Italy, and Germany (see Fig. 6.6; the officially confirmed number of cases
was 830 in mainland China, 2 in the Republic of Korea, and 1 in USA on this day).
The Military World Games is likely to have played a fatal role in the spread of
COVID-19 infection around the world. These competitions were held in Wuhan
from October 18 to November 3, 2019, with the participation of 9300 athletes from
6.13 The World
85
figure is R 0 = 1.99.
Unfortunately, we could correctly apply formula (4.20) only in February–March
2021 (after moments of time corresponding to t final ), but as early as September 26,
2020, the number of registered cases in the world 32,730,945 (see, e.g., [86])
already significantly exceeded theoretical estimates V 1 . In Table 6.25, we have
used the inequality V f > 32,730,945 to calculate the lower limit of possible values
of relative error. It can be seen that the accuracy of SIR simulations of the global
first wave (e will exceed 79–85%) is the lowest one (in contrast to the situation for
the EU countries, and even to USA, the UK, Ukraine, and the Republic of
Moldova). So, the second and subsequent global waves of the COVID-19 pandemic
began before the end of the first wave. We will discuss this in detail in the following
chapters.
The SIR curves corresponding to prediction 1 are shown in Figs. 6.6 and 6.7.
The epidemic dynamics in the world (brown lines and markers) was compared with
the situation in USA (blue), Italy (green), Spain (yellow), the UK (red), and South
Korea (magenta). The markers represent V j values taken for calculations (“circles”),
comparisons (“triangles”) and verifications of calculations (“stars”). The number of
laboratory confirmed cases in Wuhan, China, is shown by brown “squares.” These
values were calculated in [69] with the use of information from [6]. Solid brown
line and brown “triangles” in Fig. 6.6 illustrate a big difference between number of
calculated and actual cases which can be explained by the fact that many infected
people do not have symptoms and there were and still are problems with their
detection. In particular, the hidden periods (time between the estimated epidemic
beginning t
Ã
1 and the first confirmed case) can be rather long.
The value t
Ã
1 estimated in prediction 1 (the beginning of the epidemic in late
September 2019) does not look very reliable, since the registered number of global
cases V j was higher than the theoretical estimation V(t) in February 2020 (compare
brown “triangles” and brown solid line in Fig. 6.6). The above examples of SIR
simulations in different countries show the opposite picture. Therefore, the estimate
of the value of t
Ã
1 obtained in prediction 2 is more credible, because all values V j are
below the corresponding theoretical curve V(t) (see Fig. 6.29). The beginning of the
pandemic should be sought in early August 2019, and in Ukraine it probably began
in early 2020 (according to forecast 8, the results of which are also shown in
Figs. 6.29 and 6.30).
Dashed magenta curve in Fig. 6.29 illustrates that more than 2000 persons could
spread the infection on December 31, 2019—the day when China notified WHO
about the situation in Wuhan. On January 23, 2020, this city was locked down, but
the number of infected persons could be estimated by 6000 with hundreds of cases
in USA, Italy, and Germany (see Fig. 6.6; the officially confirmed number of cases
was 830 in mainland China, 2 in the Republic of Korea, and 1 in USA on this day).
The Military World Games is likely to have played a fatal role in the spread of
COVID-19 infection around the world. These competitions were held in Wuhan
from October 18 to November 3, 2019, with the participation of 9300 athletes from
6.13 The World
85