Hybrid Immunity


    In News

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

    What is Immunity?

    • Immunity refers to the body’s ability to prevent the invasion of pathogens. Pathogens are foreign disease-causing substances, such as bacteria and viruses.

    Types of Immunity

    There are broadly two types of immunity: active and passive.

    • 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 vaccine.
    • 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 newborn baby acquired passive immunity from its mother through the placenta.

    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: IE