From UPSC perspective, the following things are important :
Prelims level : Types of vaccines
Mains level : Effectiveness of various vaccines against COVID
Vaccines like Biological E’s Corbevax and Bharat Biotech’s Covaxin that are made by traditional methods are “just as effective” as the latest mRNA technology-based vaccines a/c to US scientists.
What are Vaccines?
- A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease.
- It typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins.
Types of Vaccines
There are several types of vaccines, including:
- Inactivated vaccines
- Live-attenuated vaccines
- Messenger RNA (mRNA) vaccines
- Subunit, recombinant, polysaccharide, and conjugate vaccines
- Viral vector vaccines
 Inactivated vaccines
- Inactivated vaccines use the killed version of the germ that causes a disease.
- Inactivated vaccines usually don’t provide immunity (protection) that’s as strong as live vaccines.
- So you may need several doses over time (booster shots) in order to get ongoing immunity against diseases.
- Inactivated vaccines are used to protect against: Hepatitis A, Flu (shot only), Polio (shot only), Rabies etc.
 Live-attenuated vaccines
- Live vaccines use a weakened (or attenuated) form of the germ that causes a disease.
- Because these vaccines are so similar to natural infection that they help prevent, they create a strong and long-lasting immune response.
- Just 1 or 2 doses of most live vaccines can give you a lifetime of protection against a germ and the disease it causes.
- They need to be kept cool in refrigerated conditions.
- Live vaccines are used to protect against Measles, mumps, rubella (MMR), Rotavirus, Smallpox, Chickenpox, Yellow fever
 Messenger RNA vaccines
- Researchers have been studying and working with mRNA vaccines for decades and this technology was used to make some of the COVID-19 vaccines.
- mRNA vaccines make proteins in order to trigger an immune response.
- mRNA vaccines have several benefits compared to other types of vaccines, including shorter manufacturing times and, because they do not contain a live virus, no risk of causing disease in the person getting vaccinated.
How does mRNA vaccine work?
- The mRNA vaccines function differently from traditional vaccines.
- Traditional vaccines stimulate an antibody response by injecting a human with antigens.
- mRNA vaccines inject a fragment of the RNA sequence of a virus directly into the cells, which then stimulate an adaptive immune response mRNA fragment is a specific piece of the virus that carries instructions to build the antigen of the virus.
- An advantage of RNA vaccines is that they stimulate cellular immunity.