Fig. 3 Scenario of epidemic development in Russia without restrictive
measures. (Source: Covid-19-scenarios.org)
Increasing RO per unit significantly accelerates the process, if RO is
2, then the first infected person transmits the virus to two more
people, then each of them transmits the virus to two more people and so
on.
The index of the current COVID-19 coronavirus is about three. When the
authorities restrict people’s contacts, the reproduction index
decreases. Now all countries are trying to lower the reproduction rate
below 1, hoping that at a slow rate of infection, restrictive measures
can be eased (Fig. 2).
Reducing the reproduction index does not yet mean defeating the virus,
but a low infection rate can be controlled through more economical
measures - wearing masks, mass testing, tracking contacts and timely
isolation of people with symptoms.
In order to model the coronavirus distribution, the University of Basel,
Switzerland, developed an interactive model based on SEIR, where data
(number of inhabitants, age structure, number of confirmed cases, etc.)
are loaded automatically and RO is assumed to be 2.64-3.23.
If no restrictive measures were taken in Russia, according to this
model, 1.3-1.36 million people would have died by the beginning of July,
and the number of infected people at the peak of the epidemic would have
been 14-22 million (Fig. 3).
If Russia eases the restrictions so that the number of people’s contacts
will increase by 50%, the number of new infections may increase to
300,000 by May 31, 2020, and if nothing is changed or the number of
contacts reduced by another 50%, the increase in infection will be
almost invisible or not at all.
Based on mathematical modeling of COVID-19 epidemic development in
Moscow, 5 scenarios of epidemic suppression and their possible
consequences are presented [18]. The extended SEIR model [15],
implemented as a public computer program, was used for modeling. 5
scenarios of the epidemic development are considered: 0 - zero scenario
corresponds to the absence of protective measures, scenario A - a mild
step to suppress the epidemic (closure of schools, universities,
recommendations to elderly people not to leave home), scenario B and D -
a complete knockdown, introduced in scenario B from the beginning of
May, in scenario D - from the beginning of April 2020. In the O-variant,
the number of deaths from COVID-19 in Moscow will exceed 100 thousand
people, and the number of critical patients at the peak of the epidemic
will exceed the capacity of the healthcare system by more than 10 times.
Scenarios A and B do not radically reduce the number of deaths, and the
number of critical patients at the peak of the epidemic will continue to
far exceed the capacity of the health system. In addition, scenario B
assumes that the epidemic will last for more than a year. Scenarios B
and D can suppress the epidemic and significantly reduce the number of
deaths (by 30 and 400 times, respectively). At the same time, as a
result of these two scenarios, the population does not develop
collective (group) immunity and the population will remain susceptible
to repeated outbreaks of the epidemic.
Of the 50,000 Moscow citizens who voluntarily tested, antibodies to
COVID-19 were found in 12.5-14% who are developing or have developed
immunity to the coronavirus. Rather, the examined patients suffered from
the disease in an asymptomatic or mild form, without contacting medical
professionals. Based on the results of these studies, it can be assumed
that those who acquired immunity during the asymptomatic course of
COVID-19 in Moscow may be from 1,586,000 to 1,776,000 people, and the
total number of infected, including officially registered (applied for
medical care) patients then is from 175,000 to 1,946,000 people.
Consequently, the proportion of those identified in medical
organizations is only 8.69-9.64% of the total number of infected
people.
During the last month, the growth of COVID-19 cases has been gradually
decreasing: for example, during April 15-19, 2020, this figure was
14-15%, May 1-5, 2020 - 7-8%, and during the last week it dropped to
3% (21.05.2020).
In Sweden, the pandemic strategy included the following measures: 1. Do
not interrupt business activities. 2. Don’t disrupt people’s daily
lives. 3. Systematically move towards achieving collective immunity.
Citizens were asked to observe social distancing precautions, but they
were not required to do so and were not penalized for non-compliance.
Two weeks ago, the health care system was on the verge of collapse, but
the situation has improved and there has been no collapse. The number of
infected people is still growing, and the death rate is higher than in
other Scandinavian countries, but lower than in countries that have
taken radical isolation measures. WHO now considers the Swedish model to
be a possible model for countries waiting for a vaccine.
The effectiveness of COVID-19 restrictive measures to prevent the spread
of infection has been studied comparatively in the states of Iowa (where
they were not introduced) and Illinois, where these measures were
introduced from March 21, 2020. [17]. In addition, the difference in
the timing of closure of schools and businesses, population density and
income levels were taken into account. The population density was higher
in Iowa (114.2 people per square mile) than in Illinois (78.2 people).
Summarized COVID-19 cases for 10,000 populations in both states were
compared prior to the State of Illinois self-imposed isolator ordinance.
After the decree, the incidence became higher in Iowa, decreased in
Illinois. Within 10, 20, and 30 days of the Illinois Home Isolation
Ordinance, the difference in COVID-19 cases was 0.51 per 10,000
residents (SE 0.09; 95%, CI is from 0.69 to 0.32; p<0.001;
-1.15 per 10,000 population (SE 0.49; 95% CI is from -2.12 to -0.18;
p=0.02) and -4.71 per 10,000 population (SE 1.99; 95% CI is from -8.64
to -0.78; p=0.02), respectively. These data demonstrate the
effectiveness of home isolation to prevent the spread of COVID-19 even
in selected regions of the country.
Medical organizations are known to be one of the frequent outbreak
centers of infection. Often, when such a focal point arises in a general
hospital, infected patients are transferred to other hospitals, creating
a chain of infectious disease outbreaks, sometimes from infectious
disease hospitals to non-infectious disease hospitals for surgical
interventions. It is always a high risk of infection for patients and
medical staff. It seems reasonable to introduce a surgeon to infectious
diseases hospitals and to organize an operating room.
Conclusion. Analysis of the prevalence of the new coronavirus disease
COVID-19 over a 4-month period from the initial ”emotional” assessment
based on intensive indicators is gradually moving to a system of
”medical statistics”. The actual epidemiological situation, trends and
prognosis can be most reliably assessed and determined based on relative
morbidity and mortality rates.
It is necessary to distinguish such indicators as ”morbidity”,
”infection rate”, ”mortality” and ”lethality” according to the generally
accepted postulates of medical statistics and epidemiology. Proper
calculation of such indicators as morbidity (number of patients with
COVID-19 per 1,000/100,000 of population), the rate of infection (or
reproduction), allows to objectively assess the effectiveness of various
restrictive measures in dynamics, helps to make decisions about the
continuation or weakening of these activities, and for the health system
- about the possibilities for the near future to cope with the upcoming
flow of patients or make adjustments to strengthen their resources.
Approximately the same importance of another indicator - mortality (the
number of deaths per 100,000 population), although it characterizes the
state, the level of health care system. Indicator - lethality (%
deceased to the number of patients) - is primarily an assessment of the
activities of medical organizations, medical workers, the level of
medical knowledge, professionalism, the state of implementation of
research results. Undoubtedly, the level of lethality is also connected
with material and technical, medical equipment of medical organizations,
opportunities of conversion of medical organizations into infectious
diseases hospitals, organization of intensive care and resuscitation
departments, providing the latter with equipment for non-invasive and
invasive ventilation of the lungs, hemodialysis, efferent methods of
treatment.
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