Hybrid Immunity

Context: A recent study in the journal the Lancet Infectious Diseases held that “hybrid immunity” provides better protection against severe Covid-19.

Immunity and types of Immunities:

• Immunity refers to the body’s ability to prevent the invasion of pathogens. Pathogens are foreign disease-causing substances, such as bacteria and viruses.
• Active Immunity: It develops from the exposure to a disease thereby triggers the Immune system to produce antibodies to that disease.
  • Active immunity can be acquired through natural immunity or vaccine-induced immunity.
• Infection-induced immunity is defined as the immune protection in an unvaccinated individual after one or more infections.
• Vaccine-induced immunity is acquired through the introduction of a killed or weakened form of the disease organism through vaccination.
  • For example COVID-19 vaccines, Covid shield and Covaxin.
• Passive Immunity: It is provided when a person is given antibodies to a disease rather than producing them through his or her own immune system.
  • For example, a new born baby acquired passive immunity from its mother through the placenta.

About Hybrid Immunity:

• Hybrid immunity is defined as the Immune protection in individuals who have had one or more doses of a COVID-19 vaccine and experienced at least one SARS-CoV-2 infection before or after the Initiation of vaccination.
• Exposure to SARS-CoV-2 through infection or vaccination triggers the production of antibodies that can be readily measured in the blood (referred to as ‘seroconversion’).
• If the level of antibodies in the blood exceeds a pre-specified threshold, the individual is said to be ‘seropositive’.
• The percentage of seropositive individuals in a population at a given time point is referred to as the seroprevalence of SARS-CoV-2 in that population.

Source: Indian Express

Previous Year Question

Q.1) In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements:

1. The Serum Institute of India produced COVID-19 vaccine named Covishield using mRNA platform.
2. Sputnik V vaccine is manufactured using vector based platform.
3. COVAXIN is an inactivated pathogen based vaccine.

Which of the statements given above are correct?

1. 1 and 2 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3