IMMUNITY AND COVID-19

By: Dr. Samayug Bhowmik, Bureau Chief, ICN West Bengal

KOLKATA: Today in this turbulent pandemic caused by Novel Corona Virus or Sars-Covid2, our very existence is at stake. When novel Corona Virus (COVID-19) started to spread worldwide from Wuhan of China, since then , we have been terrified as till date, there is neither defence nor cure. We are trying to find the way to escape or fight with the virus out rightly.

What are the ways by which we can do the same? The list is as follows.

1. By way of maintaining social distancing, wearing face mask, washing hands with soap water/ disinfecting with Alcohol (at least 70%) containing sanitizer.
2. Detect more cases in a community by doing more tests.
3. Isolating the test positive individuals and quarantining the related contacts.
4. By imposing Lockdown

But what about the people who are infected with Covid-19 and turning critical and even those that succumb to death? Why are a large number of people with Covid positivity requiring hospitalization and around half of them are in Intensive Care Unit?

A few days ago, the answer has been found to be Lack of Immunity or Immunodeficiency which is frequently associated with old age or co- morbid state of the infected individual. It may be associated with or without having intake of immunosuppressive drugs which lowers our immunity or their long association with pre-existing disorder such as Diabetes, Hypertension, kidney disorder, Heart ailment or Cancer. This in turn reduces the self defense or immunological protection of the affected individual and thus the person may be affected by Covid-19.

Here comes the question of individual immunity of a normal person as well as of the old age or co-morbid patients. It is important to know what is Immunity and how it works to produce a defense against the attacks by different invaders.

Immunity is defined in a simplified way as a state of balance in our body produced by different cells and tissues
1) To create a protection against different bacterias, viruses etc.
2) To produce adequate biological defenses
3) To fight infection as well as to fight with a disease
4) To guard our body from unknown, unwanted biological invaders.

Now we have to know how our body gains immunity. Here it is discussed in a simplified way, as possible, for which we should have to clear some nomenclatures etc as below..

Antigen: The Invaders that try to attack us. They may be Virus, Bacteria etc.

Genome: It is defined as a particular structure inside a cell where whole of the hereditary prints as well as newly changed informations of a living creature are stored.

In our body more than 3 billion genomes are present.

Our Blood: It is composed of cells and plasma. All the cells originate from our bone marrow. The cells are mainly Red blood cell, White blood cell, Platelets of which white blood cell consists of Neutrophil, LYMPHOCYTES, Eosinophil, Basophil and Monocyte .

Here we will mainly concentrate on Lymphocytes only.

B-Cell: They are the B type Lymphocytes coming from bone marrow

T-Cell: They are the T type Lymphocytes although developed from bone marrow later goes to a gland inside our body called Thymus where they become a fully matured T-Cell.

Memory cells: They are the lymphocytes keeping the mirror image memory of the first or previous attack done by an antigen and later they are capable to fight against a same antigen. It is mainly constituted by T-Cells and partly by B-Cells.

Cytokines: They are small protein like materials used for signaling the target.

Inflammation: It is a process of complex biological response which tries to fight and drive out antigen.

Immunity in our body develops mainly in two ways. It maybe INNATE i.e. immunity since birth and ACQUIRED i.e. the immunity that develops throughout our life by introduction of vaccines, plasma or antibodies or antibodies from mother to child or a patient, gained after some infection etc.

Now l will discuss each one with some elaboration.

A. Inborn Immunity or Innate immunity: It is also called as native immunity. This innate system of our body is composed of a primitive bone marrow cell from which B- Cell are generated which are programmed to recognize foreign substances and where to react. It is a type of defense mechanism that comes into play immediately or within few minutes to hours of an antigen’s appearance in our body. This type of immunity is also assisted by skin, or by different chemicals in the blood. Thus it is targeted to produce a defense if same chemical or invader comes to attack us. The best examples are production of cough, production of mucus etc.thats why we are often reluctant to suppress or abolish the cough of a patient by prescribing any cough syrup.

B. Adaptive or Acquired immunity: Our body develops more advanced lymphocytes mostly they are coming from the organ Thymus which are,as mentioned earlier, as T-Cells. They are programmed in such an way that they are able to recognize different chemicals, different cells and other substances which are inside in our body and in a normal person in a normal state they does not react with them. Adaptive immunity targets towards the specific antigen or invader. The process of adaptive immune response is more complex than innate immunity. Their reaction with any substance or with the invaders initiates a war between the soldiers inside our body and the antigen coming from
invader, where our inside soldiers are always trying to win by applying different weapons they have in their stock.

Thus after getting a stimulus from an antigen and by a response from adaptive immunity, severe inflammation occurs in and outside in the body of a disease affected individual occurs and are also documented by very high rise of different detrimental markers in our body.

The other side of this story is, in our body, as we are also developing or acquiring Acquired Immunity, it develops in two ways. They are known as Active and Passive immunity. See how they are acquired. We acquire it either from somebody or by introduction of something in our body.

Active immunity is developed either naturally from an infection or artificially by introduction of a vaccine and may protect us for a long time even lifelong, barring some drawbacks in the cases of certain vaccination e.g. in the question of Influenza and Pneumonia vaccination where repetition is required.

As the strains of viral genomes are changing frequently, to incorporate newer strains, repeated vaccination is needed after certain intervals.A similar situation may arise if any vaccine develops for novel corona virus as the virus is very rapidly changing its genome in many folds.

Passive immunity is developed naturally from mother to baby or artificially by introduction of Plasma, Transfer of antibodies etc. The induction of passive immunity has been used for over a century to treat infectious disease, even before the advent of antibiotics, and was often the only specific treatment for certain infections. It provides immediate protection, but in this case, the body does not develop any memory, therefore the patient may be again at risk of being reinfected by the same invader later on.

Passive immunization is required when there is a high risk of infection and or insufficient time for our body to develop its defense to fight with the invaders or to reduce the symptoms produced by an already ongoing disease e.g.at present time during treatment of Covid-19 victims.

Now comes to the issue of HERD IMMUNITY which is the talk of not only the town but the subject of discussion worldwide.

What is HERD IMMUNITY? It is a type of protection acquired by the people of a large population of a country or in a community in a state of prevailing infectious disease, when they are protected either by community spread of the disease or by introduction of large scale vaccination among the people at risk. Herd immunity is said to be achieved when at least 70-80 % of a population gets this immunity against a specific disease.

Thus, in case of high infectivity status of Covid-19, to get Herd immunity without a vaccine, if we allow free mixing of people, the virus can infect many people even majority people of a country or world in a few months.Thus, all hospitals will be over flooded with patients and the hospital system overwhelmed. This will lead to higher death rates. In Italy, we have seen how the hospitals unable to manage the exponential spurt in number of patients requiring critical care were selective in choosing patients with higher chance of recovery over those that
had less chance of the same due to age or existing comorbidities.

But at the same time, with exposure, a major population will have the disease with minor symptoms or be asymptomatic and develop antibodies. Herd immunity will then result.

On the other hand, if we maintain the current guidelines of social distancing, sanitization etc, we may achieve rather reduced or a static rate of new cases of infection till a vaccine comes. That might take a year or more. As learned from previous outbreaks of Smallpox before the vaccine was developed, people sometimes intentionally exposed themselves to achieve immunity although the disease was infectious. But not like this current infection causing by COVID-19.Which carries a much higher risk of severe disease and death.

Again to note that allowing free mixing of peoples in a community is not at all a good idea to get immunity in a large population. On the contrary it may be an unwise, futile and rather may be a devastating attempt which will invite more casualties and mortality as previously experienced by us in 1918 Flu Pandemic.

The other side of the story is that, as immunity is playing its major in Covid-19 victims and as stated earlier, the Cytokines, which are produced in enormous quantity to fight against the antigen of Covid-19, is called as Cytokine Storm. This further causes a more disastrous state of the patient leading to Multiorgan failure and leading to death.

Now we are in dilemma that whether it is the virus or our hyperactive immune system that kills the Covid-19 victim. Again to alert you, as stated earlier, immunity is a state of balance produced by different cells and tissues of our body. Thus all of us should be more cautious whether we should hyperboost our immune system by taking different products or not.

The question is- Should we over indulge in available products from indigenous medicine or strictly follow the scientific guidelines and protocols?

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