Allaying the fears that the third wave of Covid-19 pandemic would affect children between 2-18, an ongoing study by researchers from the All India Institute of Medical Sciences (AIIMS), in New Delhi and others suggested that the SARS-CoV-2-sero-positivity rate was high among children and was comparable to their adult counterparts. Hence, it is unlikely that another wave would disproportionately affect children.

There were interim findings of the study, supported by the World Health Organisation, and were based sero-surveillancesurvey carried out on over 4,500 volunteers, of which 700 were aged between 2 and 17 years. The final study, expected to be completed in two to three months, would cover 10,000 participants, mainly from Delhi, Gorakhpur, Bhubaneswar and Agartala.

Higher sero-positivity rate

According to the study, for which the data was collected during March and June this year, sero-positivity rate was higher in Delhi Urban at 74.7 per cent. This was much higher than 56.1 per cent reported during the fifth sero-survey in January this year.

Among all the four cities selected for the study, the Gorakhpur site has the highest sero positivity rate of 87.9 per cent, while Faridabad had the least sero positivity rate of 58.8 per cent. “The data collection of all the sites was done just before the second wave hit the country except the site of Gorakhpur. This may be the reason for the highest prevalence at the Gorakhpur site among all the sites,” the study said while adding that overall, more than half of the participants, 62.3 per cent, showed evidence of past infection.

Meanwhile, Agartala site included some tribal population as well. As per the study, in general, the tribal population had lower mobility resulting in lower vulnerability to Covid-19 infection. This might explain the comparatively low prevalence in children at this site.

“In a rapidly evolving pandemic, individuals who have been recently infected (< 14 days) may not have developed antibodies. They would have been reported negatively in sero-survey. Hence, our findings are likely to be an underestimate,” the report said.

The report further said that children had a slightly lower sero-positivity rate than adults - 55.7 per cent versus 63.5 per cent. These findings are similar to the previously reported evidence that children are less affected than the adult age group.

“During the pandemic schools were closed and children were more likely to have remained indoors compared to adults. For children, the source of infections is likely to be the household adults who brought the infection from outside during livelihood activities,” the report stated while further adding, “hence, we can expect some lag in sero-positivity among children. We are not sure if children produce the same level of antibodies as adults when infected.”

Source of infection

If children produce a lower level of antibodies that might not be detectable by the existing laboratory tests, then the observed sero-positivity rate would reflect the laboratory tests proficiency rather than any actual true difference between children and adult infection rates. Overall, the results suggest that children and adults are equally susceptible to Covid-19 infection.

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