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Second national sero-survey

Topics Covered: Issued related to health.

Second national sero-survey:


Results of the second national sero-survey have been released by the Indian Council of Medical Research (ICMR).

What are Sero-surveys?

They are conducted by drawing blood samples and checking for a specific class of antibodies called IgG that appear within two weeks of an infection. Because it is yet unclear how long antibodies detectably persist in the body, their presence only indicates past exposure to — and not presence of — the virus.

Findings of the latest survey:

  • Around 7% of India’s adult population may have been exposed to the novel coronavirus till the last fortnight of August.This is roughly a 10-fold jump in numbers from the first sero-survey conducted by the Council across 70 districts in 21 States that sought to estimate the likely number of infected until early May.
  • During the first survey, it emerged that there were 82-130 infections for every confirmed COVID-19 positive case. That number has now dropped to 26-32 infections.
  • However, the numbers also suggest that the country still has an overwhelming majority of its population yet to be exposed to the virus and therefore, is far from any peak or herd immunity levels.
  • The country wide prevalence of the virus was similar to that seen in the United States, which was around 9.3%. Brazil and Spain had a prevalence of 2.8% and 4.6%.



Prelims Link:

  1. What is RT PCR?
  2. What is ELISA based test?
  3. What are antigens and antibodies?
  4. Differences between IgG and IgM antibodies.
  5. What is ICMR?

Mains Link:

Discuss how Enzyme-Linked Immunosorbent Assays (ELISAs) Based test is carried out to detect the presence of SARS- COV2 in individuals.

Sources: the Hindu.