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What the serosurvey results in India imply?

Topics Covered: Issues related to health.

What the serosurvey results in India imply?


Context:

Over the last two months, Serosurveys have been conducted in various cities across the country including Delhi, Bangalore, Mumbai and Pune.

  • These serosurvey results suggest Covid-19 is far more widespread than virus tests show.

Key findings:

  • In Punemore than 51%of those who were tested showed the presence of antibodies specific to the novel coronavirus, suggesting that about half the population of this city of 4 million could have already been infected.
  • An earlier exercise in Delhi had suggested that the actual spread could be 40 times the number of confirmed cases.
  • As per the second survey, 29% of Delhi has antibodies for Covid-19.
  • In Mumbai, about 40 per cent of the sampled group was found to be infected.

Key takeaways from these findings:

  1. More Asymptomatic cases: These numbers confirm the general impression that most SARS-CoV2 infections are asymptomatic (some estimates say approximately 80 per cent are asymptomatic). Of course, the virus could be spreading from asymptomatically infected people too, especially within families.
  2. Inadequate tests: From a capacity to test just a few hundred samples at the start of the outbreak in March to more than eight lakh tests a day now, there has been a massive upgrade in the testing infrastructure. And yet, the serological tests show that a vast majority of the infected people are still being missed out, particularly those who are not showing symptoms.

Is it leading to herd immunity?

Scientists warn against interpreting these results as an indication of the percentage of population that might have become immune to the disease. The serological surveys are not designed to detect neutralising or “protective” antibodies in human beings.

  • All antibodies are not protective. It is only the neutralising antibodies that can make a person immune to the disease.
  • Besides, Scientists still do not know the level of infection in the population at which “herd immunity” would start to play a role.

Need of the hour:

Adequate testing is crucial to containment strategies. It is the only method to identify, and isolate, infected people and their close contacts.

  • The more the tests, the greater the chance of detecting infected people, including those who are asymptomatic. Timely isolation of these can prevent transmission to other people.

A higher number of tests, therefore, has a direct bearing on slowing down the spread of the disease.

Insta Concepts:

What is sero survey? What it indicates?

The serological survey is one that involves collecting blood samples to:

  1. Determine whether a person is infected with the novel coronavirus.
  2. Detect whether the person was infected with the said virus in the past.
  3. Identify antibodies being produced to combat COVID-19.

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Sources: the Hindu.