20%, and if the people will be not protected and isolated enough, hundred millions
in the world can be infected. The global mortality rate in September 2020 was
around 3%, [52]. It means, we have to work hard on protection and isolation to
avoid millions of deaths and reduce the number N.
Now it is possible to formulate the recommendations following directly from the
presented SIR model:
1. Do not panic. Together we can fight the epidemic!
2. Minimize the number of contacts and trips, not visit crowded places. Work and
study remotely where possible.
3. Refrain from shaking hands and kisses during meetings. Use masks in crowded
areas. Refrain from having sex with people you do not know (more than half of
those infected have no marked symptoms).
4. If you (or others) have any suspicious symptoms, do your best to avoid the
spread of the infection. Call a dedicated service that should isolate and verify
all suspects and contacts.
5. Authorities should organize such services and disseminate information as far as
possible about symptoms of the disease, where and how to contact them when
necessary.
Unfortunately, too many people do not follow these simple and not very burdensome recommendations, which increases the number of cases (we see a particularly threatening increase in September and October 2020). Moreover, there are
a large number of active corona skeptics who organize mass protests against
quarantine measures. Mostly, they are young people, often inspired by hostile
propaganda. The disease in young people can be mild, often without symptoms. But
we must not forget that children and young people can bring the infection to their
older relatives and friends, who may die. It is clear that strict quarantine measures
are detrimental to the economy, but in a pandemic we cannot live as we did before.
It is now the task of governments and society to develop optimal strategies to
contain the pandemic without significant economic losses.
The SIR model is the simplest one. It is unable to determine the duration of the
incubation period (for this purpose a susceptible-exposed-infectious-recovered
(SEIR) model can be used, see, e.g., [7, 57]) and to predict the number of deaths
caused by coronavirus. More complicated approaches can be found also in [58–65],
but the advantage of SIR model is small number of differential equations and
unknown parameters. This fact allows estimating the values of parameters with the
use of limited data volumes and making adequate predictions of the duration of
epidemics in different countries, estimates of their actual beginning (they may
precede the time of registration of the first patient), to calculate the time dependence
of the total number of patients V = I + R and I, to estimate the probability of
meeting an infected person and the effective reproduction numbers. Corresponding
results for mainland China, USA, Germany, the UK, the Republic of Korea, Italy,
Austria, Spain, France, the Republic of Moldova, Ukraine, and the city of Kyiv will
be presented in next chapters.
4 Classical SIR Model and the Exact …
25
in the world can be infected. The global mortality rate in September 2020 was
around 3%, [52]. It means, we have to work hard on protection and isolation to
avoid millions of deaths and reduce the number N.
Now it is possible to formulate the recommendations following directly from the
presented SIR model:
1. Do not panic. Together we can fight the epidemic!
2. Minimize the number of contacts and trips, not visit crowded places. Work and
study remotely where possible.
3. Refrain from shaking hands and kisses during meetings. Use masks in crowded
areas. Refrain from having sex with people you do not know (more than half of
those infected have no marked symptoms).
4. If you (or others) have any suspicious symptoms, do your best to avoid the
spread of the infection. Call a dedicated service that should isolate and verify
all suspects and contacts.
5. Authorities should organize such services and disseminate information as far as
possible about symptoms of the disease, where and how to contact them when
necessary.
Unfortunately, too many people do not follow these simple and not very burdensome recommendations, which increases the number of cases (we see a particularly threatening increase in September and October 2020). Moreover, there are
a large number of active corona skeptics who organize mass protests against
quarantine measures. Mostly, they are young people, often inspired by hostile
propaganda. The disease in young people can be mild, often without symptoms. But
we must not forget that children and young people can bring the infection to their
older relatives and friends, who may die. It is clear that strict quarantine measures
are detrimental to the economy, but in a pandemic we cannot live as we did before.
It is now the task of governments and society to develop optimal strategies to
contain the pandemic without significant economic losses.
The SIR model is the simplest one. It is unable to determine the duration of the
incubation period (for this purpose a susceptible-exposed-infectious-recovered
(SEIR) model can be used, see, e.g., [7, 57]) and to predict the number of deaths
caused by coronavirus. More complicated approaches can be found also in [58–65],
but the advantage of SIR model is small number of differential equations and
unknown parameters. This fact allows estimating the values of parameters with the
use of limited data volumes and making adequate predictions of the duration of
epidemics in different countries, estimates of their actual beginning (they may
precede the time of registration of the first patient), to calculate the time dependence
of the total number of patients V = I + R and I, to estimate the probability of
meeting an infected person and the effective reproduction numbers. Corresponding
results for mainland China, USA, Germany, the UK, the Republic of Korea, Italy,
Austria, Spain, France, the Republic of Moldova, Ukraine, and the city of Kyiv will
be presented in next chapters.
4 Classical SIR Model and the Exact …
25