Recently Russian vaccine Sputnik V received emergency use authorisation (EUA) in India. Four vaccines namely Covid Shield, COVAXIN, Moderna and Sputnik have received the EUA.
After the second wave of COVID-19 hit India, people across the nation started to take vaccination seriously. While people are realising the importance of getting the entire population vaccinated to fight Corona, many rumours about different vaccines keep making their way into the market, making people fearful of its side effects.
In this blog, we would discuss
- how vaccines work,
- all COVID vaccines with Emergency use authorization (EUA) in India
- their working mechanisms and
- how each of them is different from the other.
What is a vaccine?
A vaccine is a biologically active substance produced to impart immunity against a particular infectious disease.
A vaccine typically contains a biological component that mimics a disease-causing microorganism that is made from:
- weakened or killed forms of the microbe,
- its toxins,
- or one of its surface proteins
The body’s immune system gets triggered by the component to recognise the targeted microbe as a threat and create antibodies to destroy it. The body further recognises and destroys any similar microorganism in the future.
Origin of vaccine
Vaccine is derived from Variolae vaccinae (smallpox of the cow). Edward Jenner used this phrase in the title of his study ‘An Inquiry into the Causes and Effects of the Variolae Vaccinae, a Disease discovered in some of the Western Counties of England, particularly Gloucestershire, and known by the name of the Cow Pox’ in 1798.
In this study, he described the protective effect of cowpox against smallpox which had killed the world’s 10% population by then. Jenner developed the concept of vaccines and created the first vaccine as well against smallpox.
That’s why Edward Jenner is also called the father of Immunology and the science of vaccine development and production is termed vaccinology.
Ever since their invention vaccines have been saving millions of lives across the globe every year.
Vaccines can be divided into different categories. We will discuss primarily six categories based on the type of biological component used:
- Attenuated: This type of vaccine uses a weakened form of the microbe that is devoid of all virulent capabilities but is capable enough to trigger the immune response against the disease. Example: Measles, mumps, & rubella (MMR combined vaccine)
- Inactivated: This type of vaccine contains the same microbe but something that has been made inactive by chemicals. Polio (IPV) and
Hepatitis A vaccines are inactivated.
- Toxoid: The inactivated toxic compounds from the pathogen that causes the illness is used to make such vaccines. Examples: tetanus and diphtheria.
- Subunit/Conjugate: this type of vaccine are made from a segment of the pathogen. Examples: Hepatitis B, Influenza (injection), Haemophilus influenza type b (Hib) etc
- mRNA vaccines: A messenger RNA vaccine contains nucleic acid RNA, packaged within a vector such as lipid nanoparticles and teach our cells to make a protein that triggers an immune response inside our bodies and creates antibodies.
- Viral Vector vaccines: Such vaccines use a safe virus as a vehicle to transport the genes of the pathogen in the body to produce specific antigens, such as surface proteins, to trigger an immune response. This immune response is triggered when such a similar virus attacks the body in future.
Most of the COVID-19 vaccines are mRNA vaccines like Pfizer, Moderna, Covaxin etc.
What is COVID-19?
Coronavirus is a category of viruses and some of them can cause diseases. One such coronavirus was identified in 2019, SARS-CoV-2. This virus has caused a pandemic of respiratory illness, called COVID-19.
The disease can be harmless with mild or no symptoms or it can be fatal as well. Once it enters the body, it wants to multiply and attack the respiratory system.
In most cases, our immune system can handle it but in some cases, it can’t. And that is why COVID-19 has caused over 41 lakhs of death across the globe and 4 lakhs in India.
In such extreme situations when death is staring all of us in the faces we can’t just rely on protective measures like wearing a mask and washing our hands.
All these measures have to be supplemented with vaccination to save as many people as possible. But the post-COVID world is also inflicted with fear and all kinds of rumours are doing rounds against the vaccine.
Now that even Sputnik has got Emergency use authorization (EUA) in India along with Indian vaccines Covaxin and Covid Shield the confusion has increased.
Let’s understand the difference between these vaccines.
COVID -19 vaccines
Introduction: COVAXIN, codenamed as BBV152 is India’s first indigenous, inactivated vaccine. It is developed by Bharat Biotech in collaboration with the Indian Medical Research Council (ICMR) and the National Institute of Virology (NIV) for the treatment of highly infectious disease Covid-19.
Country of Origin: India
Manufacturer: Bharat Biotech
Vaccine Type: inactivated vacccine
Working Mechanism: This vaccine was created by isolating a SARS-CoV-2 virus strain from an asymptomatic COVID-19 patient at India’s National Institute of Virology. After producing large stocks of the coronaviruses, researchers used beta-propiolactone to inactivate (unable to multiply) the coronavirus by bonding to its genes. But the proteins inside the virus remain intact. Then the researchers extracted the inactivated viruses and mixed them with an aluminum-based to boost its response to a vaccine. The inactivated cells after entering the body do not multiply but trigger the antigen presenting cell for creating antibodies.
Introduction: Covishield is the vaccine developed by Oxford University & Astra Zeneca. It’s codename is AZD1222. The vaccine is marketed by the Serum Institute of India in India.
Country of Origin: United Kingdom
Manufacturer: Oxford University & Astra Zeneca
Vaccine Type: viral vector vaccine
Working Mechanism: The Oxford-AstraZeneca vaccine is a viral vector vaccine.This vaccine uses double-stranded DNA to send genetic instructions for building the spike protein. The researchers added the gene for the coronavirus spike protein to another virus called an adenovirus (ChAdOx1). It can enter cells, but can’t multiply inside them. Once vaccine is injected the adenoviruses bump into cells and gets engulfed by the cell in a bubble and pulls it inside. The adenovirus escapes from the bubble and travels to (nucleus) where, the cell’s DNA is stored. The gene for the coronavirus spike protein can be read by the cell and copied into a molecule, mRNA. Then cells start making spike proteins which eventually triggers a strong immune response in the body. The debriss of the vaccinated cells can also be taken up by antigen presenting cells.
Introduction: Sputnik V (Gam-COVID-Vac ), was the first COVID-19 vaccine to be registered for use. It has received approval in 67 countries, including India. In May, “Sputnik Light”a one-dose version was authorized for emergency use in Russia.
Country of Origin: Russia
Manufacturer: Gamaleya Research Institute of Epidemiology and Microbiology
Vaccine Type: viral vector vaccine
Working Mechanism: Sputnik V also uses double-stranded DNA like Covishield to send virus’s genetic instructions for building the spike protein. Sputnik V is a viral vector vaccine which uses two human adenoviruses Ad5 and Ad26. The working mechanism is almost same as Covishield.
But hey, how do I decide that which vaccine is best for me?
Well, all the vaccines authorised in India have passed certain safety checks. You do not need to worry about any vaccine. The best vaccine is the one that is first available to you.