Will the vaccine really free us from Covid-19? Are we safe if we get vaccinated?
To understand the effectiveness of the coronavirus (SARS-CoV-2) vaccine, we need to understand exactly what effect a vaccine has on the human body. For this, first of all we need to understand how the human body prevents any infection.
When a bacterium or virus enters our body, its main goal is to increase its own numbers. Germs accomplish this purpose by using different components of our body and as a result we get sick. The human body's immune system is also designed to prevent infection with various weapons.
Various weapons of the immune system
There are two stages of immunity in our body. The first step is Internet immunity, which can be called ‘first line of defense’. This reaction starts as soon as you come in contact with a germ (within minutes or hours). Several patterns are found in germ cells, which are present only in the case of germs. In Innate Immunity our body identifies enemies by looking at this pattern. After identifying the enemy, a special type of cell lands on the ground, called a macrophage. It is a special type of white blood cell that can swallow a variety of germs or dead cells in one word. However, this internet immunity is not long-term. But the macrophages that are activated as a result of awakening to the Internet of Immunity are the ones that trigger the next level of immune response.
The second step is adaptive or acquired immunity, which is what gives us long-term protection from any germs. Some special types of white blood cells, B-lymphocytes or B-lymphocytes and T-lymphocytes or T-lymphocytes help to develop adaptive immunity. B-cells are mainly made up of bone marrow, hence the name ‘B’ cells. They basically make antibodies that later attack a special element (antigen) that comes from the germ. Since these antibodies can be detected from our body fluids or humor, this type of response is called the humoral immune response. The bone marrow is also the source of T-cells, but in their immature state they move to the thymus, where mature T-lymphocytes are formed. And that’s why ‘T’ is the name of the cell. Their main job is to attack and destroy the infected cells.
Learning to recognize the enemy
Just like it takes some time for you or me to learn to do something for the first time, it takes a lot of time for our body to identify the enemy and prevent disease when the first infection occurs. But in the future, if the same bacteria or virus attacks again, but our immune system does not delay a moment to recognize the enemy. This is made possible by a special type of B and T-lymphocyte, called memory cells, or the immune system. These memory cells instruct B-lymphocytes to make antibodies whenever they see a known bacterium.
This time let's talk about vaccines. Speaking of the first attack by an unknown enemy for so long, the vaccine mimics exactly that. It has two main advantages. First of all, we don't have to be as sick as we would be if we were attacked by an unknown germ. This is because vaccines are made with infectious germs or specific germs (such as proteins, DNA or RNA, etc.). Second, our immune system also underwent a training, which created memory T cells and B-cells, so that in the event of a future attack by this germ, it can immediately send him a letter. But keep in mind that it is not possible to develop immunity to the disease with the vaccine. After being successfully vaccinated, our body takes quite some time (at least 10-15 days) to produce immune B-cells and T-cells. Therefore, if someone is infected just before or after getting the vaccine, they will get sick.
But is it enough to get vaccinated once? This of course can be particularly different in the field. There are some vaccines that can alert our immune system once taken but some vaccines require multiple doses, called booster doses. Different vaccines may require a booster dose. As with some vaccines that do not cause an adequate immune response to the initial dose, a booster dose is needed (e.g. meningitis vaccine), while some vaccines require a booster dose (e.g. diphtheria) even if the immune system gradually weakens a few days after the initial dose. Disease vaccine).
The various steps involved in creating a vaccine
But creating a vaccine is no easy task. There are many steps that can be taken to make a vaccine for a disease.
There are six steps to developing a vaccine:
Step 1: Researchers are looking for a natural or artificial antigen that can be used to defeat an enemy.
Pre-clinical stage: This antigen (possible vaccine) is tested on cells, tissues or model animals. The purpose of the test is to test whether the immune system has developed. If this is not the case or the damage is reversed, then the next step is not to proceed.
Third step (clinical trials): Here the test is done in three steps. A non-governmental organization tests volunteers directly, gradually increasing the number (less than 100 at first, more than 100 in the second phase, and about 10,000 or more at the end). If the antigen passes all the tests, then it goes to the fourth step.
Step 4 (regulatory review): In this step, the application for biological license is sent to the Drug Control Board of the country concerned (such as FDA in USA, CDSCO in India, etc.). This vaccine can be made on a large scale only with the consent of the people.
Step 5: Manufacturing: A large pharma company undertakes to manufacture and distribute vaccines on a large scale.
Step 6 (quality control): The FDA and other regulatory bodies monitor the effects of vaccines.
All that has been said about vaccines for so long is exactly what is expected from an effective vaccine.
The Covid-19 vaccine has come a long way
About 9 months after the Covid-19 infection, people around the world are now asking when the vaccine will come. Or how effective it will be?
Scientists around the world have been researching the vaccine day and night in the wake of this Covid-19 parasite. Expected results have been matched. There are still at least 13 vaccine phase-3 trials around the world, and more than 30 vaccines are in various primary trials (phase 1 or 2). The most notable of these is the ChAdOx-1, a joint venture between Oxford University and AstraZeneca. The vaccine was developed by inserting a special protein (spike protein) gene from the corona virus (SARS-CoV-2) into the infectious adeno virus.
Preliminary studies have shown that this vaccine is able to prevent SARS-CoV-2 infection in non-human primates (such as monkeys, orangutans, gorillas, etc.). In the Phase-1/2 clinical trial, the vaccine was given to 543 volunteers in initial and booster doses (26 days apart). Tests have shown that in most volunteers, the vaccine produces antibodies. It is undoubtedly a beacon of hope. The vaccine is currently undergoing a phase-3 clinical trial with 30,000 volunteers in different countries. However, the trial was adjourned for a few days after a volunteer fell ill unexpectedly. However, the trial has started again from October 5 in Britain. Recent results have shown that this vaccine works well in older people (between the ages of 60 and 70). But we will have to wait until the end of the phase-3 trial for the final result. The vaccine is a joint venture between the Indian pharmaceutical company Serum Institute and Astra Zeneca.
Another phase-3 trial of the vaccine, run by Johnson & Johnson in the United States and Belgium, was conducted with 60,000 volunteers, but was temporarily suspended by the organization. The reason is that unexpected illness. According to experts, this is not uncommon in any vaccine trial. But the good news is that the trial has started again from the last week of October.
The vaccine, a joint venture between the National Institutes of Health and Moderna, has also yielded the expected results and is also in phase-3 clinical trials. Preliminary reports have shown that the vaccine is about 94% effective in preventing SARS-CoV-2. However, it is not possible to say anything definitively until the end of the phase-3 clinical trial.
Pharmaceutical companies Pfizer and BioNTech have jointly developed a number of mRNA vaccines, and two of these vaccines (BNT162b1 and BNT162b2) have yielded the expected results in phase 1/2 clinical trials. Preliminary data from a recent phase-3 clinical trial in the United States showed that the BNT162b2 vaccine is 90% effective in preventing SARS-CoV-2 infection. However, the full results of this phase-3 clinical trial may be available later this year.
Most of the vaccine phase-3 clinical trials so far have been able to produce significant amounts of antibodies in the human body. However, in almost every vaccine, a booster dose has to be given after the initial dose, and in each case, some initial symptoms have been observed, such as fever, body aches, headache, dizziness, etc. after vaccination. However, these types of symptoms often occur after the vaccine. Researchers at Oxford have found that common paracetamol reduces these symptoms.
All the vaccines I have talked about so far have to be injected intramuscularly. Recently, a team of scientists from the University of Washington School of Medicine was experimenting with an intra-nasal vaccine. They found that the vaccine was much more effective than nasal sprays than intramuscular injections. Studies have shown that this vaccine is able to prevent the transmission of SARS-CoV-2 in the upper and lower respiratory tract (respiratory tract) in rats. Vaccine maker India Biotech will launch a phase-3 clinical trial of the vaccine in India in a joint venture with Washington University School of Medicine.
Other barriers to effective vaccine development
In the light of so much hope, scientists still have some questions. One of the reasons for this is the second corona infection. Such information has been obtained from several places in the world. But why is this happening? But our body is not able to build long-term immunity? Or is it the second time the same virus has attacked another strain or type? Scientists still have no clear idea about this. Patients with SARS-CoV-1 or MERS (Middle East Respiratory Syndrome) corona virus infections, such as SARS-CoV-2, have been shown to have immunity for up to 2-3 years. After 5-6 years but it decreases. Since the novel Corona virus or SARS-CoV-2 is a completely new virus, nothing is known about its resistance to infection. Scientists are also constantly trying to understand the whole thing from new information. And that's why no matter how promising the vaccine may be, we still don't know how long the antibodies produced by the vaccine will last in our body. Or will the same vaccine work equally well for people of all ages or geographical locations? Time will tell.
There is another problem. That is the problem with storing so many vaccines. Most of the vaccines that are still being worked on have to be kept at -20 degrees or -60 degrees Celsius, which can be very costly for a poor country.
Another problem with vaccine development is the antibody-dependent enhancement of disease, or ADE for short. Antibodies that can protect us from disease have the ability to increase the spread of disease in an unwanted way. Experts believe that this could happen if the vaccine does not produce enough antibodies. However, those viruses that attack macrophages are more likely to be at risk of ADE. Although ADE has been shown in pre-clinical trials in some animals (non-human) who have been vaccinated against SARS-CoV-2, it is not yet clear whether the SARS-CoV-2 vaccine will be ADE. This requires many more experiments.
After all, the way scientists around the world are working on vaccine research may one day find a solution to this disease. But once an effective vaccine is made, it will take at least 2-3 years for it to reach every human being. So now it is our duty to wear masks, wash our hands frequently with soap and avoid unwanted crowds. That way we can protect ourselves and the people around us.
Note: The thymus is a type of gland located between the two lungs of the human body at exactly the same height as the heart. By the age of one year after the birth of a human child, the thymus has rapidly formed