All COVID-19 vaccines are not the same? Know the facts about the ones that are ready for rollout

Now, after so many months of uncertainty, we have quite a few COVID-19 vaccines ready for rollout. But are they all the same? Know the facts.

With the imminent rollout of COVID-19 vaccines in India and elsewhere in the world, many people are wondering about the different vaccines developed to fight the virus. Many vaccines are being developed across the globe to fight the pandemic and researchers claim varying degrees of efficacy of each. But are these vaccines the same and will it have the same effects? No, all the vaccines are not the same. But yes, all these vaccines are designed to teach the body's immune system to safely recognize and block the deadly virus that causes COVID-19. Here, let us look at the types, how they are developed and their safety and efficacy.

THE FOUR TYPES OF COVID-19 VACCINES

Several different types of potential vaccines for COVID-19 are in development. But all of them fall into one of four types, depending on how they are developed. The four types are whole virus (inactivated or weakened), protein-based ones, viral vector and nucleic acid (RNA and DNA). While some of the vaccines try to smuggle the antigen into the body, others make use the body's cells to stimulate the production of the viral antigen.

Inactivated vaccines

Inactivated or weakened virus vaccines use a form of the virus that has been inactivated or weakened so it doesn't cause disease. However, it can still generate an immune response. Many of the existing vaccines are developed using this technique. Experts destroy the genetic material of the virus so that it cannot replicate. But these vaccines can still trigger an immune response in the body. Even people with compromised immune system can take these vaccines without fear of catching the disease. These can also be stored easily and is a good option for poorer countries.

Bharat Biotech's Covaxin, India's first indigenous vaccine, is an inactivated one. China's Sinovac is also an inactivated vaccine.

Protein-based vaccines

These are developed using use harmless fragments of proteins or protein shells that imitates the COVID-19 virus. This generates an immune response in the body. But one drawback of this kind of vaccine is that it may generate a weaker immune response. To overcome this problem, they are often clubbed with adjuvants to boost the immune response.

US's Novavax COVID-19 vaccine is protein-based.

Viral vector vaccines

These use a genetically engineered virus, which cannot cause disease. But it can produce coronavirus proteins to generate the body's immune response. It does so by mimicking the viral infection and triggering a strong immune response. But the drawback of this kind of vaccines is that many people may have already been exposed to the viruses being used as vectors. This may make some immune to it. In this case, the vaccine will be less effective.

Russia's Sputnik V is an adenovirus vector-based vaccine. AstraZeneca-Oxford COVID-19 vaccine is also viral vector vaccine. This is being rolled out under the name Covishield in India in collaboration with Pune's Serum Institute of India.

RNA and DNA vaccines

These use genetically engineered RNA or DNA to generate the viral spike protein. When this genetic material enters human cells, it uses the cells' protein factories to make the antigen that triggers an immune response. Such vaccines are easy to make and very cost-effective. The antigen is produced inside the body's cells in large quantities, and this makes the immune reaction strong. However, these need to be kept at ultra-cold temperatures of -70C or lower. This can be challenging especially for low- and middle-income countries.

The COVID-19 vaccines from Pfizer and Moderna are RNA vaccines.