In the peak of the second wave in Odisha, more than two in every five children below the age of 18-years in rural areas of the Smart City had an exposure to the Delta SARS-CoV2 variant, whereas the number in their adult counterpart stood at one in every two.
The Interpretation
While the serosurvey undertook by AIIMS Bhubaneswar in partnership with WHO hints at a lower infection rate among children below 18-years vis-a-vis younger and elderly adults in the rural pockets of the Capital City, the big message it delivers is kids in Bhubaneswar-rural develop antibodies against the Delta virus (as genome data earlier disclosed that nearly 85 per cent samples in Bhubaneswar had been infected by the Delta variant) almost at par (not equal) with their adult counterparts.
AIIMS Bhubaneswar Sero Survey
During the period of March 22 to May 7, 2021, the AIIMS Bhubaneswar has carried out a serological survey for Covid-19 among children below 18-years of age and adults above 18-years. A total of 1000 participants enlisted, where the ratio of kids to adults stood at 165 to 835. The median age (as per statistical measure, median means the middle age between 2-17 years) chosen here has been 12 years. A unit of 5ml venous blood collected and tested on ELISA (Enzyme-linked Immuno-Absorbent Assay) kits to detect SARS-CoV2 antibody.
The Big Results
As per the test results, a total of 75 among the 165 kid participants have been found seropositive in the City. In proportionate terms, around 45.4 per cent of children in the age group of 2-17 years had developed antibodies (IgG) against the Delta SARS-CoV2 variant in rural areas of the State capital.
Similarly, the results for the adults show that of a total of 835 adult participants (18 years and above), a high of 451 was found seropositive, which is around 54 per cent of the total.
The analysis by AIIMS, Bhubaneswar finds that, though the seropositivity rate among kids in the State capital is lower than adults, no statistically significant difference in prevalence between children and adults have been observed.
The study, therefore, concludes that the SARS-CoV-2 seropositivity rate among children was high and was comparable to the adult population. Hence, it is unlikely that any future third wave by prevailing COVID-19 variant would disproportionately affect children of two years or older.
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The sero-survey results released by the AIIMS-WHO survey are not guaranteeing so. Because the survey has very clearly mentioned that the serosurvey didn't test the presence of neutralising antibodies in the participants. And here lies the big catch.
When the human body is infected by any pathogen, including the SARS-CoV2, the body generates two antibodies - A) Binding antibodies and B) Neutralising Antibodies.
- The binding antibody (detected in the current serosurvey) binds with the pathogen virus and alerts the immune system about infection. As a consequence, the white blood cells (WBC) in the body troop in to destroy the virus. The activity of this type of antibodies lasts for only 4-5 months
- Neutralising Antibodies are also protein molecules produced by B-cells in the bone marrows. These antibodies bind to a specific antigen (the spike protein or the nucleic acid of the virus). These antibodies will give immunity against the particular pathogen for a longer period - may be up to lifetime. Moreover, their highest significance lies in the fact that they prevent the virus to mutate and replicate in the body.
The Big Catch
In order to prevent a bigger outbreak in the State, the detection of neutralising antibodies against Covid-19 variants in the population assumes high significance. The reason is binding antibodies can prevent the Delta or any other mutant SARS-CoV2 variant for only around 5 months.
"The surge of the second wave in India occurred due to lack of good antibodies in the blood plasma of the population in the country, including Odisha. The absence of "meaningful antibodies" (neutralising antibodies) in the seropositive population has been the reason behind the second outbreak," concludes another recent CSIR survey.
AIIMS Director's Big Take
"If you want to be more realistic then you should see neutralising antibodies. In fact, the presence of antibodies means "there is some degree of protection." ahead. The binding antibodies tend to come down within subsequent four to six months after recovering from Covid infection, but some people have cell-mediated immunity, and a person's cell-mediated immunity would continue to process for months and years." explained Dr Guleria to national news agency ANI.