Delta strain dominated in children during second Covid wave, genomic surveillance recommended: Study


There has been limited information pertaining to the SARS-CoV-2 strain infecting children in India. The latest study by the Indian Council of Medical Research-National Institute of Virology (ICMR-NIV) and others has shown that the Delta strain predominated as the leading cause of SARS-CoV-2 infection in children in India during the second wave of the pandemic. Dr Samiran Panda, former additional DG of ICMR who led the study, and Dr Pragya Yadav, senior scientist at ICMR-NIV and lead author of the study, told The Indian Express that the data on newly emerging SARS-CoV-2 variants affecting the paediatric population is scarce. Hence, it is necessary to initiate active genomic surveillance in this population.

The study ‘Delta variant SARS-CoV-2 infections in paediatric cases during the second wave in India’ was published on July 2 in the Journal of Microbiology, Immunology and Infection. It assessed SARS-CoV-2 lineages in children during the second wave of the pandemic. Swabs were collected from 583 patients in the age group of 0-18 from across eight states and one Union territory from March 2020 to June 2021. These included Chandigarh, Maharashtra, Gujarat, Uttar Pradesh, Karnataka, Madhya Pradesh, Punjab and Andhra Pradesh.

Over 51.8% of the patients were in the age group of 13-19. Symptoms were reported among 37.2 patients and 14.8 per cent were reported to be hospitalised. Samples were characterised using next-generation sequencing. Out of these 512 sequences, 372 were Variants of Concern (VOC), while 51 were Variants of Interest (VOI). Most common lineages observed were Delta, followed by Kappa, Alpha and B.1.36, seen in 65.82%, 9.96%, 6.83% and 4.68%, respectively. Overall, it was observed that the Delta strain was the leading cause of SARS-CoV-2 infection in Indian children during the second wave.

The virus is expected to be endemic. Why is genomic surveillance recommended in the paediatric population?

Genome sequencing of SARS-CoV-2 has played an important role in determining its emerging variants, geographical predominance, evolution over different times and understanding its trend. The emergence of multiple VOCs suggests that as long as SARS-CoV-2 circulates in populations, new variants will continue to emerge. The strategy in many countries is vaccination of adult and vulnerable populations while allowing the virus to circulate in children; the children might be vulnerable to SARS-CoV-2 infection. This necessitates the genomic surveillance of SARS-CoV-2 in the paediatric population.

Children have low rates of severe Covid-19. What are your views on this?

The fourth Covid-19 serosurvey in India showed that more than 50% of children belonging to the 6-17 years age group were seropositive, emphasising that a huge number of children were infected like adults, but not many of them required institutional care. It has been observed that children have low rates of severe Covid-19, and the proportion of cases developing severe disease increases with age. Besides this, it has also been found that vaccination induces an immune response capable of neutralising the emerging variant. This has decreased the severity of the disease and subsequent hospitalisation.

Are any studies underway on immune response in paediatric population vaccinated with Covaxin?

In the near future, many studies will come up specifically focusing on Omicron sub-variants and newly emerged SARS-CoV-2 variants in children.

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