Some questions of epidemiology, statistics, and pandemic forecast
COVID-19.
Prof. Vil M. Timerbulatov, MD, Shamil V. Timerbulatov, MD, Prof. Mahmud V. Timerbulatov, MD.
Bashkir State Medical University, str. Lenin, 3, Ufa, Russian Federation. 450008.
Professor Vil Mamilovich Timerbulatov – head of surgery department in Bashkir State Medical University, Ufa, Russian Federation; head of Surgery Emergency Clinic, Ufa, Russian Federation; https://orcid.org/0000-0002-1696-3146;
Professor Shamil Vilevich Timerbulatov – PhD, surgery department in Bashkir State Medical University, Ufa, Russian Federation; deputy head of Clinic for Infection Diseases, Ufa, Russian Federation; https://orcid.org/0000-0002-4832-6363; e-mail:timersh@yandex.ru; phone: +79273073333;
Professor Makhmud Vilevich Timerbulatov – head of surgery department in Bashkir State Medical University, Ufa, Russian Federation; head of Surgery Emergency Clinic, Ufa, Russian Federation; https://orcid.org/0000-0002-6664-1308.
Number of words 5634.
The article analyzes the indicators of prevalence, morbidity, lethality and mortality in the new coronavirus disease - COVID-19, based on this specialized literature and official information from the state mass media. The importance of correct application of the principles of medical statistics for the analysis of these indicators in decision-making on the introduction of restrictive measures, monitoring the epidemic process, evaluating the effectiveness of these measures and the activities of medical organizations is shown. Individual pandemic forecast models are considered.
Since the World Health Organization’s announcement on 11 March 2020 of a new coronavirus disease pandemic, COVID-19, many reports of illness, especially deaths, from the media, social networks, have triggered a stormy, mixed public reaction and often fueled fear and depression in people.
In statistical processing of medical articles, packages of statistical programs are used, based on probability theory and mathematical statistics [1], i.e., in fact, the techniques of ”medical statistics” are used. The complexity of statistical analysis of medical data is caused by a number of objective and subjective factors, such as specific standards in research design, the presence of legal, economic, ethical restrictions, the great complexity of the studied phenomena, the presence of ”leads” and confusing factors, the most frequently solved problems do not completely coincide with those in other subject areas.
In the first month of the pandemic, official information from WHO and all countries reported numbers of people infected and dead (in absolute figures), with shocking effects on the population, although these figures did not reflect the status, course or trends of the epidemic. Such uncertainty in the assessment of the situation, especially ignorance of trends in the spread of COVID-19, could not contribute to the adoption of correct, justified, especially preventive decisions by the authorities, public health leaders, at least in the near future.
As of May 26, 2020 COVID-19 in the world 5,603,427 people got sick, 350,041 died, in the Russian Federation 362,342 and 3,807 respectively. The mortality rate for this infection in the world is 6.5%, the share of the infected population is 0.06445%, in Russia it is 0.96% and 0.22% respectively.
A pandemic occurs when 1 to 5% of the population is affected, but given the characteristics of the COVID-19 coronavirus, WHO has declared a pandemic with lower infection rates.
Up to 60% of those tested in Russia have the coronavirus without symptoms. The results of antibody testing of the population in Santa Clara County, California, showed that the morbidity was 50-85 times higher than the official one and, accordingly, the mortality rate was also 50-85 times lower and was 0.04-0.07% instead of 4%.
It is important to clearly distinguish between lethality (% of all deaths) and mortality, which is calculated on 1,000 or more often on 100 thousand population.
Every year 1.2 million people die from pneumonia alone, 350,041 died from coronavirus between the end of December 2019 and 26 May 2020, but the difference between dying with coronavirus and dying from coronavirus must also be considered. The vast majority of those who died suffered from cancer, chronic lung disease, obesity, diabetes, and cardiovascular disease, and the virus was the last straw during their illnesses.
According to Rospotrebnadzor (Russian Federal Service for Supervision of Consumer Rights Protection and Human Health), following the results of the influenza and acute respiratory infections epidemic in 2016-2017, the daily number of cases in Russia was 120 thousand people, which is significantly higher than COVID-19 (from 5 thousand to 10 thousand per day). Therefore, rather, the peak of the epidemic in Russia was passed 2 months ago, when there was no testing due to the total hospitalization of all infected people in hospitals, the latter have become real centers of the hospital epidemic (in 55% of centers in medical organizations), the expansion of indications was influenced by the increase in the cost of payment for medical insurance up to 200 thousand rubles per case. With the further mass conversion of medical organizations into infectious disease hospitals, the latter are loaded only by 30-35%.
On 15 January 2019 WHO announced a list of 10 major threats to human health in 2019, including air pollution and related climate change, Ebola, the global influenza pandemic, HIV and increased resistance of bacteria to antibiotics.
Every year, air pollution leads to the premature death of 7 million people.
Non-communicable diseases such as diabetes, cancer, and cardiovascular diseases are the second most dangerous, with 4 million people dying from them every year (7% of all deaths).
As of 31 January 2020, 213 people worldwide had died infected with COVID-19. During this period, 684,497 people died of cancer, 633,508 children under 5 years old, 140,112 suicides, 81,757 of malaria, 70,189 of contaminated water, 40,452 of influenza, 25,763 during childbirth.
As of March 11, 2020, the total number of COVID-19 infections in the world exceeded 118 thousand in 114 countries, according to WHO, 4,291 people died. Most of the infected were found in Italy (>10,000), Iran (9,000 cases, of which almost 1,000 died), South Korea (7,700, 242 died), and the Russian Federation had 20 infected, so at the beginning of the pandemic the global mortality rate from COVID-19 was 3.63%, in Iran - 11.1%, South Korea - 3.14%, in Russia - 0%.
Subclinical or mild forms of coronavirus disease were observed in 80.9% of patients, but they had the potential for virus spread [2] and had the same viral load as patients with symptoms of SARS-CoV-2 [3].
According to WHO, the incubation period is 5.2 days with a range of 1-14 days [4].
The average time for patients to see a doctor from the onset of symptoms is 5.8 days, and 12.5 days before hospitalization [5].
The stages of symptomatic disease were classified on the basis of non-contrast CT results and divided into early (0-4 days), progressive (5-8 days), peak (9-13 days) and adsorption (>14 days) stages [6].
Subpleural opacities (GGOs) located in the lower lobes of the lung are detected at an early stage of the disease. Bilateral spread of the infection process and diffuse subpleural turbidity are detected in the progression stage. At the peak stage, the presence of dense consolidation, residual parenchymatous strips are determined. The adsorption stage can last more than 26 days, with a more controlled process, gradual resolution, and signs of recovery [6].
In a prospective cohort study of 1,150 COVID-19 patients hospitalized in New York City, it was shown that more than ¾ of the severely ill patients needed a ventilator and almost 1/3 needed hemodialysis [7]. Of the patients in critical condition, 39% died, and 41% received invasive mechanical ventilation.
According to the National Health Service of England, Wales and Northern Ireland (11,292 patients needed intensive care), 50% of patients who received a ventilator died within 40 days after starting intensive care [8].
In the United States, at the beginning of the pandemic, there were 95,000 intensive care and resuscitation beds (28.7 beds per 100,000 population). In Russia there is no exact data, their number, according to different sources, varies from 12 thousand to 35 thousand (8.57-35.0 per 100,000 population).
The number of COVID-19 intensive care beds also varies greatly in different countries from 22.9 beds 100,000 population in Germany, 28.9 - Austria, 16.3 - France, 12.9 - Canada, 10.5 - UK, 9.7 - Spain. 8.6 - Italy, 7.8 - Denmark, 5.0 - Ireland.
In 2016, there were 197 million pneumonia cases worldwide and 1,200,000 died.
In 2017, according to the Federal State Statistics Service, over 671 thousand people suffered from pneumonia in Russia, and 26 thousand died. 26,088 died in 2017, 25,642 people died in 2018.
In 2019, 1.8 million people died from various causes in Russia, 1.67 million died directly from diseases, and 130 thousand died from external causes.
In Russia, every year respiratory diseases (influenza, acute respiratory infections, pneumonia) are carried by ≈50 million people.
According to WHO, there are ≈1 billion influenza cases worldwide every year, including 3-5 million severe cases and from 300 to 650 thousand deaths.
Table 1.
Rates of morbidity and mortality of new coronavirus infection COVID-19 in different countries (as of 30.05.2020)