A serological surveillance (sero survey) under the World Health Organization (WHO), conducted by the All India Institute of Medical Sciences (AIIMS), has allayed apprehension regarding a potential third wave of the coronavirus disease (Covid-19) pandemic in India disproportionately affecting children.
The interim findings of the ongoing sero survey point out that the SARS-CoV-2 seropositivity rate in children aged two years and above is comparable to that in adults and thus there is no statistical evidence to suggest that the 2-17 age group is especially vulnerable to a potential third wave.
The findings of the ongoing sero survey have been published on medRxiv, a pre-print server, and are based on a mid-term analysis of the data of the 4,509 participants — 700 children in the 2-17 years age group and 3,809 aged 18 years and above.
The five selected sites are as follows — Delhi Urban Resettlement Colony, Delhi Rural (villages in Faridabad district of Haryana under Delhi-NCR), Bhubaneswar Rural, Gorakhpur rural, and Agartala rural. Data was collected between March 15 and June 10 from these selected sites.
Here are the key interim findings from the ongoing sero survey conducted by WHO and AIIMS:
1 . The seroprevalence, presence of virus-fighting total serum antibodies against the Sars-CoV-2 virus, was assessed qualitatively by using a standard ELISA kit in five states with a proposed total sample size of 10,000.
Among children aged 2-17 years, the seroprevalence was found to be 55.7% across the five selected study sites, in comparison to 63.5% among adults. The difference was judged to be statistically insignificant.
2 . Regardless of the age group, rural sites reported a lower seropositivity rate on average as compared to urban sites in Delhi. Even within rural sites, children reported a lower seropositivity rate as compared to adults. However, this difference was not observed in the urban sites.
3 . The interim findings show that female children show a slightly higher seropositivity rate than males, which is in contrast to the meta-analysis which initially showed a higher seroprevalence in men. The findings may continue to change as more data become available, the study said.
4 . Higher mobility and independence may be a reason behind the higher seropositivity rate in children aged 10-17 years, when compared to that in younger children.
5 . In Delhi, which was one of the five sites for the study, the researchers found that 74.7% of the population – both children and adults – had been exposed to the infection. This is a much higher seroprevalence than the state government’s survey from January where 56.1% were found to have antibodies against the virus.
The samples for the AIIMS study were collected between April and May, and would not have detected antibodies of those who got the infection during the second wave.
6 . A large proportion of children (50.9%) had asymptomatic Covid-19 infection. Even before the second wave, children below the age of 18 in South Delhi had as much seroprevalence (73.9%) as the below 18 years (74.8%).
7. As compared to the 74.7% in urban settlements of South Delhi, the prevalence was 59.3% in the villages of Delhi and Ballabhgarh.
“Results show that a large majority of the population had already been infected by the time we conducted the study at Delhi urban site which belongs to lower and middle socioeconomic strata population and very congested neighbourhood,” the study said.
8. With all locations other than Delhi being rural, the average seroprevalence in rural areas stood at 58.8% as per the study. The highest seroprevalence was found in Gorakhpur, Uttar Pradesh where 87.9% of the people had been exposed to the infection.