The Coronavirus disease 19 (COVID-19) is a highly transmittable & pathogenic viral infection caused by Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) which caused global pandemic that led to dramatic loss of human lives. Coronavirus can be classified into 4 genera namely; Alpha coronavirus, Beta coronavirus, Gamma coronavirus, and Delta coronavirus. When we look at its morphology it is large, enveloped, single stranded positive sense RNA virus with 5′ cap structure and 3′ Poly A tail structure & genome ranges from 27 to 32kb. It encodes 4 structural proteins on its surface, namely Nucleocapsid(N) protein, Membrane(M) protein, Spike(S) protein and Envelop(E) protein & several non-structural proteins. The genome is packed inside a helical capsid formed by nucleocapsid protein (N). The membrane protein(M) & envelope protein (E) are involved in virus assembly, whereas spike protein(S) mediates virus entry into host cells. The genetic material of the virus, RNA is made up of molecules, each part of this code contain instructions for how to make one specific protein that allows the virus to function. A virus has one goal, to make more of itself because it’s so simple it can’t do by its own, so it uses us. Every time virus infects a person it uses their cells to make copies of itself, while replicating this code again & again it eventually makes a mistake, sometimes it deletes or adds a letter, that mistake is called mutation and it slightly changes instructions for making the virus & that slightly altered virus is a variant.
ACCESS TO THE HUMAN CELLS
Virus has envelope containing spike protein on its surface. This spike protein on virus unlocks/ gains access to interior of human cell through ACE2( angiotensin converting enzyme2). Virus uses ACE2 as receptor to unlock the human cells. It has not been entry point for just coronavirus, but also for multiple virus. ACE2 receptor exists abundance on the surface of lung cells.
There is another second protein called TMPRSS2 which allows virus to reproduce & eventually leads it to transmission within the cell. It was found that cells from nasal cavity, eye, lung, gut, heart and kidney have these proteins. Now the virus overcomes the cell metabolism to its own advantage and uses cells to multiply & make its own replicas, so within 2 days you have millions of viruses in your body. Now your body starts recognizing this invasion, body then fights by producing antibodies which recognizes foreign virus, attacks them and kills them. This is the normal process that takes place in the body when any foreign bodies attacks.
Now within 4-5 days, when antibodies are sufficient in number, viruses are large in number there is fight between these two(antibodies & viruses). Our immune system now produces certain chemicals into bloodstream know as CYTOKINES these are chemicals that causes the body to have higher temperature, bodyache, like incase if you have throat infection, you experience sore throat this is because, cells in the throat have maximum of viruses & there is a fight going on inside and hence because of the irritation you get cough.
Incubation period for virus means, from the entry of the virus to its first symptom, on an average of 5 days. 1st symptom maybe fever, bodyache, headache, even diarrhea and has to be kept in the mind as first day of infection producing symptom. If fever goes higher or sore throat persist for 3 continuous days and on 4 -5 day if your fever comes down and you have no symptoms, check for another 5 days & if you have no symptoms, then you are a Corona Warrior. 80% of the people have only minor symptoms which settles in 3-4 days. Remaining 10-20% people takes dangerous turn. Fever which had settled within 4-5days, it comes back or if it was there now you have a higher degree of fever & if you had a cough, now you experience deep hacking cough. The 3 symptoms indicating that your disease is taking to a dangerous turn are;
- Higher fever than before or if you have no fever, you will have new fever with higher temperature
- Chest congestion or difficulty in inspiration & expiration process.
- Deep hacking cough, which makes you difficult even when you are sleeping.
CYTOKINE STORM
When a foreign invaders enters our body, our immune system produces antibodies to destroy them. But sometimes our immune system gets hyperactivated & instead of killing foreign invaders, it gets excited itself & start killing its own cells, leading to cytokine storm.
Cytokines are the small proteins produced by the immune system, which act as signaling molecules that convey the message between different immune system cells. Your immune cells uses cytokines to communicate. Cytokine proteins are important in order to have unified immune response against foreign invaders. These signaling molecules are produced by many different immune cells, such as Mast cells, macrophages, B-cells, T- cells. There are few types of cytokines namely
Interferons – These protein inhibit virus from replicating. If a cell gets invaded by a virus, this signals other cells to put a shields so that virus doesn’t spread.
Interleukins- These protein regulate immune and inflammatory responses. They are mainly produced by white blood cells & their job is to send signals to WBCs to report for duty.
Chemokines- These call the cells to the site of infection. The ability to call in other cells using chemical message is a process referred to as chemotaxis.
Now if we get infected with virus or bacteria, the cytokine concentration increases and due to hyperactivated response of immune system, it releases more cytokines to signal neighboring immune cells & this leads to fail in identifying/differentiating between invader and our own cells.
CYTOKINE STORM EFFECTS
When virus attacks lung cell, they cause damage to cell. The damaged cells releases chemicals including histamine, prostaglandins etc .These chemicals sends signals to WBCs to recover from damage & to releases cytokine. When cytokines comes in the close proximity to the lung cells, there will be a huge rush of cytokines, signaling more & more WBCs to come in, now this area results in swelling. As more & more cytokines are moving in the close proximity to damaged lung cell, the wall of blood vessels becomes thinner and thinner, this causes leak of fluid from blood vessels into neighbouring lung tissue & as fluid is moving to lung tissue, now water content from blood vessels are moving out leaving with only a cellular components in blood vessel and due to this reason, blood cells in the blood vessels start sticking instead of free flow, leading to blood clot and when there is a clot formation, the required amount of blood, oxygen won’t reach to your different organs & hence Cytokine storm leads to Multiple Organ Dsyfunction. That’s the reason why most of the covid patient faced comorbidity death like liver failure, kidney failure, heart failure which is the part of cytokine storm.
DIAGNOSIS OF STORM
When our own cells have turned against us. We need to prevent release of cytokines in the body, we need to suppress our immune system. There are certain factors/ indications which has to be checked to prevent cytokine storm.
- Ferritin protein; Increases high before the cytokine storm.
- C- Reactive Protein(CRP) ; Increases high, not only here but in any sort of infection in the body.
- Interleukin 6 ; Increases high, in the case of viral infection.
WHY FIRST LUNG CELLS ?
Virus is recognized by human body by our immune system, spike protein on the surface of virus is recognized by antibodies. Some cells in our body have similar appearance & structure to that of virus spike protein, these are specifically seen more in the blood vessels of lungs .
In the lungs, antibodies which are supposed to only attack foreign viruses, recognizes these similar cells & attacks them, causing normal cells to damage. when the cells get damaged, the normal smoothness of blood vessels interior is lost, cells lining the wall of blood vessels become rough hence blood cells start sticking there, resulting in formation of clot & blocks the passage of blood vessel and no more blood can pass. So if this happens in lungs, the normal exchange of oxygen that happens b/w air and your blood in the alveoli of your lung is not going to happen, no blood flow, no oxygenation and when no oxygenation your saturation of oxygen in your blood keeps going down, you start feeling breathlessness & have a problem in breathing depending upon the severity of damage to the lungs. This is all not because of virus persisting in your lung but because body’s reaction to the viruses, autoantibodies attacking our own cells.
ROLE OF STEROIDS
On 5th or 6th day if patient has come up with high fever, bad cough & breathlessness, saturation below 94% this is where steroids has to be given to prevent cytokine storm and another important thing is, steroid alone doesn’t stop the clotting of blood within the lung blood vessel, so we have to combine it with anticoagulant. The 2 medication which has to the taken at this stage, steroids with anticoagulant. In the case of steroids, timing is very important & taking steroids all alone without the consultation is again a dangerous thing. Taking steroids at the early stage of disease ( first 5 days of the disease), results in multiplication phase of the virus to be prolonged, leading your disease to be prolonged.
Steroids are used to treat inflammatory conditions which may be seen in serious COVID-19 cases. WHO recommends corticosteroids (i.e dexamethasone, hydrocortisone or prednisone) to give orally or intravenously for the treatment of patients with severe COVID-19. Treatment showed to reduce the length of time on ventilation for the patients with critically ill. Steroids has to be taken once a day for atleast 7-10 days & anticoagulants has to be continued for 3 weeks, not 10 days like steroid because tendency of blood clotting has 3 weeks, so that it can cover. Dosage of the steroid shouldn’t be more than 2mg/kg. Though steroids are effective to reduce infection associated with inflammation but they suppress our immunity. When you are on the course of steroids & anticoagulants dramatically you become better, fever is gone, cough is better, but again on 5th day on the course of steroids, you start having a fever again and this time it is not virus, but as normal immunity is being suppressed, a normal bacteria in your lungs attacks your body and causes Pneumonia which should be covered with antibiotics. Steroids do benefit in huge way in life saving way, but it encourage infection by bacteria within our lungs and this is the only stage, when antibiotics has to be taken. Taking antibiotics at the 1st symptom is actually encouraging bacterial resistance, resulting in bacteria becoming resistant against drug, because no antibiotics ( like Azithromycin or Doxycycline) do anything in eliminating the virus, they doesn’t work against virus But are useful in protecting patient from bacterial pneumonia which happens at the 5 day after starting steroids. Steroids are diabetogenic- those who are pre-diabetic they become frank diabetic, when they are on steroids which is the another drawback of steroids.
Than taking our disease to more complications and to the dangerous turn, let’s prevent it and it is important to take right medication at the right time and to follow the simple protocols, such as wearing a mask, social distancing, washing hands. The novel coronavirus spreads so rapidly that it has changed rhythm of the globe. SARS-Cov-2 virus entered our country in March 2020 and somehow we managed to come out of first wave. It again strike our nation in its mutant form & thus Covid 19 second wave emerged. Now again epidemiologists and various scientists have predicted 3rd wave. So let us together prevent it.
World of Science 