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Tuesday, Jul 28, 2020 13:30 [IST]

Last Update: Tuesday, Jul 28, 2020 07:52 [IST]

Still along way to go

As the number of cases in India rapidly increase, the health authorities are conducting serological surveys among certain people across the country.
To estimate the extent of infection in the community, scientists at the National Centre for Disease Control, a Health Ministry body tasked with monitoring epidemics, conducted a district-wise serological survey across Delhi from June 27 to July 10.
Preliminary findings showed that 23.48% of Delhi’s population had been exposed to the virus and that a large number of those infected were asymptomatic. An interpretation of these results is being taken to suggest that so far in Delhi, around 46 lakh people could have been infected by the novel coronavirus, as a result of which they developed antibodies against it, and that the country was approaching a stage of herd immunity. Such a suggestion was also put forth by Chief Minister Arvind Kejriwal on Friday, according to reports.
Unlike the real time RT-PCR (reverse transcription-polymerase chain reaction) tests or antigen tests that scan for the presence of the coronavirus in the body, the sero-prevalence survey was designed to look for the presence of antibodies, produced in response to the coronavirus, in the blood. On an average, antibodies can be detected five days after an infection sets in. The coronavirus, in general, diminishes after 21 days. Antibodies, for a host of other viral infections, are normally expected to linger for many months and confer protection against fresh infections by the same virus.
However, it is still too early in the evolution of SARS-CoV-2 to know how long the antibodies will last. According to health experts, because the actual virus withers away quickly, many of those infected show mild symptoms. Antigen and PCR tests are often cumbersome to be widely deployed in the field and are not always the best way to estimate the spread of the virus. After the Indian Council of Medical Research led a multi-institutional study in May to estimate national sero-prevalence using the Kavach-ELISA antibody-detection kit, developed and tested in India, the government decided to do a similar study across Delhi. In June, the city was grappling with a high number of cases and several parts of the city were locked into containment zones.
The report said that scientists have warned against such broad conclusions, since the sero surveys had been conducted for the purpose of answering some very specific questions. Talking about herd immunity at this stage is premature and misplaced. The Delhi government has said it will keep repeating these surveys at periodic intervals to gauge the spread of the infection. The survey found that nearly eight of the 11 districts had a sero-prevalence exceeding 20%. To the Delhi government, the fact that after six months of the global pandemic there was a 23% spread was indicative of the effect of lockdown and containment zone management.
However, since it is not possible to test everyone in the country, the report states that so far it is unclear how many people of the population were actually infected, especially since a lot of them are asymptomatic. Testing for the presence of antibodies in random sets of people is taken to be an indirect method of determining how widespread the virus is in the community.
But the government also cautioned that the survey showed 77% of the population to be vulnerable to the infection; therefore, measures such as masks, hygiene, social distancing ought to be strictly adhered to.

Sikkim at a Glance

  • Area: 7096 Sq Kms
  • Capital: Gangtok
  • Altitude: 5,840 ft
  • Population: 6.10 Lakhs
  • Topography: Hilly terrain elevation from 600 to over 28,509 ft above sea level
  • Climate:
  • Summer: Min- 13°C - Max 21°C
  • Winter: Min- 0.48°C - Max 13°C
  • Rainfall: 325 cms per annum
  • Language Spoken: Nepali, Bhutia, Lepcha, Tibetan, English, Hindi