Coronavirus COVID 19

, medical expert
Last reviewed: 27.11.2021

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At the end of 2019, the world was shocked by a little-studied viral infection - the so-called "Chinese virus", or the coronavirus COVID-19. This is an acute viral pathology, which is characterized by a predominant lesion of the respiratory system and, to a lesser extent, the digestive tract. Coronavirus refers to zoonotic infections - that is, to those that can be transmitted to humans from sick animals.

Coronavirus COVID-19 is dangerous, first of all, because little is known about it, and there are no specific therapy and vaccines that can save from infection. Therefore, it is extremely important that people know as much as possible about the disease: this is necessary for the prevention and early detection of cases of pathology. It’s not in vain that they say: forewarned means armed.

Structure of the coronavirus COVID 19

Specialists were able to determine the protein structure of the coronavirus COVID-19, which allows it to enter the cells. This discovery is very important for science, because with its help it is easier to work on the creation of a specific antiviral vaccine.[1]

Previously, scientists discovered that the coronavirus COVID-19 is a direct "relative" of the infectious pathogen SARS (SARS) . However, after the experiment it turned out that the finished antibodies to the SARS pathogen are not able to bind the "Chinese" coronavirus. What is the matter?

Scientists have described the S-protein structure that covers the viral membrane and plays the role of the main tool for cell damage. Proteins “mask” and take on the form of molecules necessary for the cells: this gives them the opportunity to bind to certain enveloped receptors and get inside. In particular, the coronavirus S-protein COVID-19 interacts with ACE2 (angiotensin-converting enzyme).

Using the microscopic CEM method, it was possible to determine the three-dimensional organization of the protein surface of the “Chinese” coronavirus with a resolution of less than 3.5 Angstroms. Specialists began to study the original, not introduced into the cell S-proteins.

As a result, the molecule practically did not differ from that of the causative agent of SARS infection. But some points of difference were still present: for example, the segment entering into contact with the ACE2 receptor had increased affinity for the target, which is responsible for the quick and easy infection of cells and the further spread of the pathogen. Antibodies to SARS infection are not able to strengthen well on the S-proteins of the coronavirus COVID-19, so the expected binding action does not occur. However, research into the viral structure is ongoing.[2]

Life cycle of the coronavirus COVID 19

Coronaviruses have long been known to science. This is a rather large-scale viral family that can provoke the development of various pathologies - mild variations like the common cold, and the most severe ones (in particular, such complex coronavirus infections as the Middle East respiratory syndrome MERS-CoV, acute respiratory syndrome SARS-CoV). The last known causative agent, the coronavirus COVID-19, is a new culture of microorganisms that has not yet been identified in humans.

The life cycle of the coronavirus COVID-19 does not need DNA, and this is its significant difference from other RNA-containing infections that have already been studied (for example, HIV). This, in particular, explains the ineffectiveness of antiretroviral treatment used to suppress the development of HIV. The carrier of genetic data in the coronavirus is not DNA, but a single RNA strand lasting 20-30,000 nucleotides. This means that the virus protein is produced by the affected cell immediately on RNA, which disguises itself as matrix RNA of the carrier. After penetration into the cell, the virus produces a specific enzyme substance, RNA polymerase, which creates copies of the virus genome. Next, the affected cell produces the remaining proteins, and new virions begin to develop on it.

Microscopic examination of the viral particle has the form of an oval with a mass of tiny spines formed by the S-protein. This particular protein plays the role of a kind of magnet, binding to a target on the cell surface in the affected body.

According to the World Health Organization, the incubation period for COVID-19 coronavirus disease averages 2-14 days. However, Chinese doctors have already stated that there were cases when this period was extended to 27 days. Moreover, an infected person is able to spread the infection from the first day of incubation.[3]

Other interesting facts about the coronavirus COVID-19:

  • Coronavirus received this name in connection with the specific configuration of the protein compound resembling a corona.
  • Coronavirus COVID-19 was found to be less pathogenic compared to the previous similar SARS virus, which "raged" in 2003 and led to the death of 10% of sick people (for comparison: about 3% of sick people die from COVID-19).
  • According to experts, the incidence should decrease with the arrival of heat, since coronavirus develops better and persists in cold conditions.
  • The main danger of COVID-19 coronavirus is the high probability of lung damage. Most often, death occurs from the severe course of pneumonia.
  • Information on immunity after coronavirus infection has not yet been reported. At the very beginning, doctors talked about the formation of acquired immunity, but then several cases of re-illness were registered in people who had the COVID-19 coronavirus. Therefore, to date, the issue of immunity remains open.

The information announced by the Ministry of Health states: this type of coronavirus is transmitted by airborne droplets from one infected organism to another. [4

People are considered the most contagious when they show symptoms. Distribution is possible before people develop symptoms.

How easy is the virus to spread? Spread from contact with infected surfaces or objects. It is possible that a person may become infected with COVID-19 by touching the surface or object on which the virus is located, and then touching its own mouth or nose. 

The fecal-oral type of transmission is also allowed: for example, in Hong Kong, people were infected through the sewage system and unwashed hands.

There is no reason to believe that any animals, including domestic animals, can be the source of infection with this new coronavirus. To date, the CDC has not received any reports of the disease of domestic animals or other animals COVID-19. There is currently no evidence that pets can distribute COVID-19. However, since animals can transmit other diseases to humans, it is always helpful to wash their hands. [5]

Coronavirus spreads faster. Normal flu has a reproductive number of about 1.3, which means that every infected person can infect an average of 1.3 people. This number is used to measure the potential of the epidemic. When it is larger than one, the disease tends to spread. In 2009, during the H1N1 flu pandemic, the virus had a reproductive number of 1.5. Available studies show that the reproductive number of coronavirus is from 2 to 3. 

Like the influenza virus, coronaviruses are enveloped viruses, which makes them susceptible to environmental conditions such as high temperatures, drying out and sunlight. The virus survives in a drop of 28 days if the temperature is below 10 degrees, and only one day when the temperature exceeds 30 degrees.[6]


According to data reported by the European Center for the Prevention and Control of Pathologies, the following basic symptoms are characteristic of coronavirus COVID-19:

  • temperature rise;
  • cough of varying intensity;
  • difficulty breathing, shortness of breath;
  • muscle pain;
  • a strong feeling of fatigue.

Other possible signs of coronavirus may be nausea and diarrhea: they are recorded in 10% of cases, and may even precede other symptoms. In early reports from Wuhan, 2-10% of patients with COVID-19 had gastrointestinal symptoms such as diarrhea, abdominal pain, and vomiting. [7], [8]Abdominal pain was recorded more often in patients admitted to the intensive care unit than in individuals who did not require care in the intensive care unit, and 10% of patients had diarrhea and nausea 1-2 days before the development of fever and respiratory symptoms

Some patients have conjunctivitis. It can be noted that the symptoms in general have much in common with influenza infection. [9]However, some differences from the flu are:

  • coronavirus infection begins literally abruptly - the patient becomes ill, although even a minute ago nothing portended trouble;
  • the temperature rises sharply and strongly - often above 39 ° C;
  • dry cough, not relieving, debilitating;
  • shortness of breath can be accompanied by intrathoracic pain, which indicates the development of viral pneumonia;
  • Patient weakness is so pronounced that people often cannot trivially raise their arm or leg.

Coronavirus COVID-19, entering the body, primarily affects the lower respiratory tract. With influenza , the upper respiratory system is affected first.

If any suspicious symptoms appear, you should immediately contact an infectious disease doctor, or your family doctor.


If you suspect infection with coronavirus COVID-19, you must consult a doctor. If the suspicions are justified, the doctors will take the biological material from the patient and send him to a laboratory equipped with special test systems for determining the virus. These systems are available in sufficient quantities in key medical institutions and laboratories: there is no shortage of them.

The effect of such tests is based on the well-known PCR method - polymerase chain reaction. This technique has many advantages: it is common, highly sensitive, and the result can be obtained quickly enough. To determine an infectious disease, biomaterial is most often taken from the patient's nasopharynx, however, mucus, sputum, urine, blood, etc. [10], can also become a material for research, [11]

To date, several test system options have already been developed. Some of them are aimed at detecting exclusively the COVID-19 coronavirus, while others can also detect the causative agent of SARS, a severe acute respiratory syndrome. It is important that all tests allow pathology to be determined even in the very early stages of development.[12]

As for other methods of diagnosing coronavirus, they are auxiliary and can be used to assess the degree of damage to internal organs, respiratory system. For example, to exclude or confirm the development of pneumonia, radiography is performed.

Differential diagnosis

Differential diagnosis of coronavirus infection is carried out with rhinovirus infection , viral gastroenteritis, respiratory syncytial infection .


To date, there is no specific treatment for the disease caused by the coronavirus COVID-19. The main therapy is aimed at maintaining the patient's body in accordance with its clinical condition.

Chinese doctors are testing a combination of several antiviral drugs at once. High doses of the well-known anti-influenza drug Oseltamivir are used, as well as drugs for treating HIV infection, such as Lopinavir and Ritonavir. [13]Many patients have successfully undergone treatment with the antiviral drug Abidol: [14]this medicine was included in one of the treatment regimens for the coronavirus COVID-19, in combination with Ribavirin and Chloroquin phosphate, [15]interferon, or Ritonavir (Lopinavir). [16]A clinical trial of Remdesivir, [17]Baricitinib [18]for the treatment of COVID-19, has begun.

FDA-approved ivermectin for the treatment of parasitic infections inhibits in vitro replication of SARS-CoV-2 (COVID-19). A single treatment can cause a reduction of the virus by 5,000 times in 48 hours in cell culture. When treating with ivermectin, a 99.8% decrease in viral RNA associated with cells was observed (which indicates unreleased and unpacked virions). [19]Ivermectin is widely available due to its inclusion in the WHO Model List of Essential Medicines.

In addition to antiviral drugs, symptomatic therapy is mandatory. Medications are prescribed to normalize the temperature, to ease coughing, to relieve edema, etc. It is also possible to use specific immunoglobulins and corticosteroids - with increasing deterioration of the patient's condition, with prolonged lymphopenia, with reduced blood oxygen saturation.

If there are risks of developing complications from coronavirus, antibiotic therapy and mechanical ventilation are performed.

Prevention of the coronavirus COVID 19

There is no specific prophylaxis for coronavirus COVID-19 infection, although work on the development of vaccines is quite active. However, there are general ways to prevent viral diseases, which also apply to coronavirus infection. So, how to protect yourself from coronavirus damage?

It is important to regularly wash your hands and disinfect objects of systematic use (telephones, remotes, computer mice, keys, door handles, etc.).

Do not touch unwashed hands on the face, eyes, etc.

Every person should always have with them disinfectants - first of all, for hand disinfection. Coronavirus dies when exposed to alcohol.

Care must be taken when visiting areas of a large gathering of people (transport, supermarkets, etc.) - it is best to touch surfaces and objects of common use as little as possible, or wear protective gloves.

You can’t take food from a common container or pack, say hello to the hand and communicate closely with unfamiliar people - at least until the epidemiological picture on the coronavirus is stabilized.

For prevention, you can wear a protective bandage (mask), although it is more indicated for already sick people. One-time masks should be changed every 2-3 hours. Donning them again is prohibited.

At home and at work, all rooms must be systematically ventilated.

You should not take any medications "for prevention": such actions will not protect against coronavirus, however, they can "lubricate" the clinical picture in case of illness, which will negatively affect the prognosis. [20]

During the epidemic, it is undesirable to go on long trips and travels. However, if you cannot do without it, it is important to follow these rules:

  • even at the planning stage of the trip, you need to make inquiries about the epidemiological situation for coronavirus;
  • it is necessary to take and use devices to protect the respiratory system;
  • during trips, you can drink only water purchased in stores in closed containers, eat only food that has previously been heat-treated;
  • wash your hands regularly, including before meals and after visiting public areas.

It is necessary to avoid markets where animals and seafood are sold, as well as various events in which animals that can be a source of infection with a coronavirus infection are massively involved. [21]

Other important preventative recommendations:

  • Try to stay away from other people - at least not closer than 1 m.
  • Eat well, lead a healthy lifestyle, often walk in the fresh air.
  • If anyone is sick at home, notify your family doctor. If possible, provide the patient with a separate room, limit contact with him, put on a medical bandage. Wash your hands more often with detergent, disinfect objects, and ventilate rooms.

If you suspect you have had contact with a patient infected with COVID-19 coronavirus, or you have recently returned from another country, call your family doctor and explain the situation. It is not necessary to independently go to a medical institution so as not to put others at risk. Next, you should clearly follow the instructions of your doctor.


On average, the total duration of the course of the disease with the coronavirus COVID-19 along with the incubation period is a little more than one month. In the absence of treatment, as well as in other adverse circumstances, complications may develop:

  • severe intoxication of the body;
  • increasing acute respiratory failure;
  • pulmonary edema;
  • multiple organ failure.

With the development of complications, the prognosis of coronavirus pathology is unfavorable - the patient dies in many cases.

According to WHO, in Wuhan, 2% of identified patients died and about 0.7% outside Wuhan. Mortality rates are 15 times higher than conventional flu (0.13%) and H1N1 flu (0.2%). 

A study published in the medical journal The Lancet Infecious Diseases of March 30, 2020 showed that the death rate from coronavirus is lower than previously reported, but it is still more dangerous than seasonal flu at around 0.66%. This coronavirus mortality rate is lower than in previous estimates, since it takes into account potentially milder cases that are often not diagnosed, but still it is much higher than in 0.1% of people who died from the flu. [22]

As for the prognosis of the spread of viral infection, here experts voiced two options. The first of these involves the spread of coronavirus to a pandemic level. In the second option, they talk about outbreaks of the disease in different parts of the planet with the further establishment of control over the pathogen and the gradual extinction of the spread.

To improve the prognosis of morbidity, timely quarantine measures should be introduced, and mass crowds should be limited. Most experts are sure that with the advent of warming, the coronavirus COVID-19 will lose its activity, and the percentage of cases will become much lower.

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