Distinct T cell functional profiles in SARS-CoV-2 seropositive and seronegative children associated with endemic human coronavirus cross-reactivity (preprint)

SUMMARY SARS-CoV-2 infection in children typically results in asymptomatic or mild disease. There is a paucity of studies on antiviral immunity in African children. We investigated SARS-CoV-2-specific T cell responses in 71 unvaccinated asymptomatic South African children who were seropositive or seronegative for SARS-CoV-2. SARS-CoV-2-specific CD4+ T cell responses were detectable in 83% of seropositive and 60% of seronegative children. Although the magnitude of the CD4+ T cell response did not differ significantly between the two groups, their functional profiles were distinct, with SARS-CoV-2 seropositive children exhibiting a higher proportion of polyfunctional T cells compared to their seronegative counterparts. The frequency of SARS-CoV-2-specific CD4+ T cells in seronegative children was associated with the endemic human coronavirus (HCoV) HKU1 IgG response. Overall, the presence of SARS-CoV-2-responding T cells in seronegative children may result from cross-reactivity to endemic coronaviruses and could contribute to the relative protection from disease observed in SARS-CoV-2-infected children. Key words: SARS-CoV-2, Children, IgG responses, T cell response, Polyfunctional profile, endemic HCoV

The Clinical Features and Estimated Incidence of MIS-C in Cape Town, South Africa (preprint)

Background: Multisystem inflammatory syndrome is a severe manifestation of SARS-CoV-2 in children. The incidence of MIS-C after infection is poorly understood. There are very few cohorts describing MIS-C in Africa despite MIS-C being more common in Black children worldwide. Methods A cohort of children with MIS-C and healthy children was recruited from May 2020 until May 2021 from the two main paediatric hospitals in Cape Town, South Africa. Clinical and demographic data were collected, and serum was tested for SARS-CoV-2 antibodies. The incidence of MIS-C was calculated using an estimation of population exposure from seroprevalence in the healthy group. Summary data, non-parametric comparisons and logistic regression analyses were performed. Results 68 children with MIS-C were recruited with a median age of 7 years (3.6, 9.9). 97 healthy children were recruited with a 30% seroprevalence. The estimated incidence of MIS-C was 22/100 000 exposures in the city in this time. Black children were over-represented in the MIS-C group (62% vs 37%, p=0.002). The most common clinical features in MIS-C were fever (100%), tachycardia (98.5%), rash (85.3%), conjunctivitis (77.9%), abdominal pain (60.3%) and hypotension (60.3%). The median haemoglobin, sodium, neutrophil count, white cell count, CRP, ferritin, cardiac (pro-BNP, trop-T) and coagulation markers (D-dimer and fibrinogen) were markedly deranged in MIS-C. Cardiac, pulmonary, central nervous and renal organ systems were involved in 71%, 29.4%, 27.9% and 27.9% respectively. 94.1% received intravenous immune globulin, 64.7% received methylprednisolone and 61.7% received both. 39.7% required ICU admission, 38.2% required inotropic support, 38.2% required oxygen therapy, 11.8% required invasive ventilation and 6% required peritoneal dialysis. Older age was an independent predictor for the requirement for ionotropic support (OR=1.523, CI 1.074, 2.16, p=0.018). The median hospital stay duration was 7 days with no deaths. Conclusion The lack of reports from Southern Africa does not reflect a lack of cases of MIS-C. MIS-C poses a significant burden to children in the region as long as the pandemic continues. MIS-C disproportionately affects black children. The clinical manifestations and outcomes of MIS-C in this region highlight the need for improved surveillance, reporting and data to inform diagnosis and treatment.

Sex-bias in COVID-19: a meta-analysis and review of sex differences in disease and immunity (preprint)

A striking anecdotal feature of the Coronavirus disease 2019 (COVID-19) outbreak is the difference in morbidity and mortality between the sexes. Here, we present a meta-analysis of 206, 128 reported cases to demonstrate that whilst there is no difference in the proportion of males and females with confirmed COVID-19, male patients have more than double the odds of requiring intensive treatment unit admission (OR 2.5) and higher odds of death (OR 1.60) when compared to females. We review data revealing how previous Coronavirus outbreaks have demonstrated a similar pattern. Important differences in the immune response to infection exist between sexes, which are likely to contribute to this observation. In this review, we discuss these differences highlighting that females have a more robust innate antiviral response and a better adaptive immune response to infection. An appreciation of how sex is influencing COVID-19 outcomes will have important implications for clinical management and mitigation strategies for this disease.