SARS-CoV2 Wild-type and Delta VOC infection dynamics in a Paediatric
cohort in India (South)
Abstract
Background: SARS CoV-2 infection virus dynamics, severity and immune
response are different in children and adults. Limited reports of the
differential impact of variants in children exist, and none have been
reported from LMICs. Methods: We recruited a prospective cohort of SARS
CoV-2 PCR positive children between November 2020 and May 2021 and
compared virus characteristics (viral load, wild-type or delta variant),
and disease severity strata (asymptomatic, mild-to-moderate and severe)
and levels of virus-specific antibody (anti-N and anti-S) immunity after
4-6 weeks. Results: Of 79 children recruited, asymptomatic,
mild-to-moderate and severe presentation was seen in 29%, 59% and 11%
subjects, respectively. Wild-type and delta presented with similar
disease severity. Anti-S antibody levels were higher than anti-N for
both variants (wild-type or delta) (p<0.0001). Anti-S was also
higher than anti-N among asymptomatic (p=0.02) and mild-to-moderate
disease (p<0.0001)). Both anti-S and anti-N antibody levels
were higher among children with higher virus loads [quartile (Q) 1
versus Q3, p<0.05]. Anti-S levels of wild-type were higher
than Delta-infected among low (Q3) virus loads (p=0.003). Mean Ct values
of wild-type (32.5) was higher than Delta infections (25.0), (p=0.0083)
among mild-to-moderate disease. Conclusions: Viral load drives antibody
response in children. Higher loads of Delta VOC resulted in robust
antibody response in mild-to-moderate disease, not seen in severe
disease. These finding are an indication of response to future SARS
CoV-2 variants and could inform targeted vaccination when introduced in
children.