ABSTRACT
BackgroundMeta-analysis and single site studies have established that children are less infectious within a household when positive for ancestral SARS-CoV-2. In addition, children appear less susceptible to infection when exposed to ancestral SARS-CoV-2 within a household. The emergence of SARS-CoV-2 variants of concern (VOC) has been associated with an increased number of pediatric infections worldwide. However, the role of children in the household transmission of VOCs, relative to the ancestral virus, remains unclear. MethodsHere, we perform a meta-analysis of the role of children in the household transmission of both ancestral SARS-CoV-2 and SARS-CoV-2 VOCs. Results: Unlike the ancestral virus, children infected with VOCs spread SARS-CoV-2 to an equivalent number of household contacts as infected adults. Similarly, unlike the ancestral virus, children within a household were equally as likely as adults to acquire SARS-CoV-2 from an infected family member. Interestingly, this same observation was noted when unvaccinated children exposed to VOCs were compared to unvaccinated adults exposed to VOCs. ConclusionsTogether, these data suggest that the emergence of VOCs were associated with a fundamental shift in the epidemiology of SARS-CoV-2. This is unlikely to solely be the result of age-dependent differences in vaccination during the VOCs period and instead may reflect virus evolution over the course of the pandemic. summaryThe role of children in the household transmission of VOCs, relative to the ancestral virus, remains unclear. Using a meta-analysis we show that the emergence of VOCs were associated with a fundamental shift in the epidemiology of SARS-CoV-2
ABSTRACT
Children typically experience more mild symptoms of COVID-19 when compared to adults. There is a strong body of evidence that children are also less susceptible to SARS-CoV-2 infection with the ancestral viral isolate. However, the emergence of SARS-CoV-2 variants of concern (VOCs) has been associated with an increased number of pediatric infections. Whether this is the result of widespread adult vaccination or fundamental changes in the biology of SARS-CoV-2 remains to be determined. Here, we use primary nasal epithelial cells from children and adults, differentiated at an air-liquid interface to show that the ancestral SARS-CoV-2 replicates to significantly lower titers in the nasal epithelial cells of children compared to those of adults. This was associated with a heightened antiviral response to SARS-CoV-2 in the nasal epithelial cells of children. Importantly, the Delta variant also replicated to significantly lower titres in the nasal epithelial cells of children. This trend was markedly less pronounced in the case of Omicron. It is also striking to note that, at least in terms of viral RNA, Omicron replicated better in pediatric NECs compared to both Delta and the ancestral virus. Taken together, these data show that the nasal epithelium of children supports lower infection and replication of ancestral SARS-CoV-2, although this may be changing as the virus evolves.
ABSTRACT
The role of children in the spread of SARS-CoV-2 remains highly controversial. To address this issue, we performed a meta-analysis of the published literature on household SARS-CoV-2 transmission clusters (n=213 from 12 countries). Only 8 (3.8%) transmission clusters were identified as having a paediatric index case. Asymptomatic index cases were associated with a lower secondary attack in contacts than symptomatic index cases (estimate risk ratio [RR], 0.17; 95% confidence interval [CI], 0.09-0.29). To determine the susceptibility of children to household infections the secondary attack rate (SAR) in paediatric household contacts was assessed. The secondary attack rate in paediatric household contacts was lower than in adult household contacts (RR, 0.62; 95% CI, 0.42-0.91). These data have important implications for the ongoing management of the COVID-19 pandemic, including potential vaccine prioritization strategies. 40-word summaryIn household transmission clusters of SARS-CoV-2 children are unlikely to be the index case. Children are also less likely than adults to be infected with SARS-CoV-2 from a family member.
