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More antibodies produced by Covishield than Covaxin study

Topics Covered: Issues related to health.

More antibodies produced by Covishield than Covaxin: study:


Context:

A study was conducted recently to study the real-world effectiveness of vaccination in India. It was conducted on healthcare workers (HCW).

  • For the study, 515 healthcare workers from 13 States and covering 22 cities were evaluated from January to May 2021.

Key findings:

  1. Covishield vaccine produced more antibodies than Covaxin.
  2. Seropositivity rates to anti-spike antibodies were significantly higher in Covishield recipients compared to Covaxin after the first dose.
  3. Responder rate and median (IQR) rise in anti-spike antibody were significantly higher in Covishield vs. Covaxin recipient.

What are vaccines?

Vaccines train our immune system to fight a disease-causing agent, which has not yet affected a person. They prepare the body for future protection.

How do they work?

  • Vaccines are known to have a component called antigen, which is usually a part of the pathogen against which the vaccine is being developed.
  • The role of antigen, once inside the human body, is to activate the immune system in order to develop protective antibodies, without having any ability to cause the full-fledged disease.
  • This way, once a person is fully vaccinated, he or she develops antibodies and remains protected.

Covishield vs Covaxin:

  1. Covishield (the vaccine by Oxford University-AstraZeneca) is based on the viral-vectored platform.
  2. Covaxin (jointly developed by Bharat Biotech and the Indian Council of Medical Research), is an inactivated vaccine.

What are Viral-vectored vaccines?

A vector, in infectious disease biology, is what works as a vehicle to transport a disease-causing agent.

  • For example, mosquitoes are the vector of malaria, a disease caused by a parasite called plasmodium.

In viral-vectored vaccines, a virus is used to carry the target antigen gene into human cells.

  • There are many such viral vectors, which have different advantages. The most widely known are the adenovirus vectors, which cause very mild colds or asymptomatic infections in humans.
  • Covishield uses a chimpanzee adenovirus (AZD1222 or ChAdOx1), which carries the SARS-CoV-2 spike protein.
  • The chimpanzee adenovirus has been used because humans will not have pre-existing antibodies to this adenovirus.

What are Inactivated or killed vaccines?

Pathogens (viruses or bacteria) that cannot multiply cannot cause disease. So inactivating a virus or bacteria, using chemicals like formalin, can convert them into a safe immunogen.

  • Because inactivated viruses or bacteria do not multiply, we may need to use multiple doses of the vaccine and also give another substance to improve the immune response — this is called an adjuvant. The most common adjuvant is the alum but shark oil suspensions and a few others are also used.

A number of vaccines developed in China, and Covaxin in India are on the inactivated platform.

 

Insta Curious:

Did you know what RNA Vaccines, Subunit vaccines, Live-attenuated vaccines etc are? Read more

 

InstaLinks:

Prelims Link:

  1. What are antibodies?
  2. What are antigens?
  3. What are Vaccines? How do they work?
  4. Types of Vaccines.
  5. What is mRNA?

Mains Link:

Write a note on Vaccine wastage.

Sources: the Hindu.