Abstract
The coronavirus disease 2019 (COVID-19) has spread globally and variants continue to emerge, with children are accounting for a growing share of COVID-19 cases. However, the establishment of immune memory and the long-term health consequences in asymptomatic or mildly symptomatic children after severe acute respiratory syndrome coronavirus 2 infection are not fully understood. We collected clinical data and whole blood samples from discharged children for 6–8 months after symptom onset among 0-to-14-year-old children. Representative inflammation signs returned to normal in all age ranges. The infants and young children (0–4 years old) had lung lesions that persisted for 6–8 months and were less responsive for antigen-specific IgG secretion. In the 5-to-14-year-old group, lung imaging abnormalities gradually recovered, and the IgG-specific antibody response was strongest. In addition, we found a robust IgM+ memory B cell response in all age. Memory T cells specific for the spike or nucleocapsid protein were generated, with no significant difference in IFN-γ response among all ages. Our study highlights that although lung lesions caused by COVID-19 can last for at least 6–8 months in infants and young children, most children have detectable residual neutralizing antibodies and specific cellular immune responses at this stage.
Highlights
Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is wreaking havoc worldwide [1,2,3]
18 patients experienced mild pneumonia (58%), 11 patients presented with acute upper respiratory tract infection (AURI)
Mild elevations in the levels of inflammatory markers such as C-reactive protein (CRP), procalcitonin (PCT), and D-dimer, a biomarker associated with COVID-19 disease severity, returned to the normal range at follow-up, as well as those of other serological markers of the patients (Supplementary Table S2)
Summary
Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is wreaking havoc worldwide [1,2,3]. There is still little information about the magnitude or stability of the immune response in this large population and whether the development of immune memory varies depending on the age of the individual or the severity of the disease. In response to this need, we recruited 31 convalescent children who had asymptomatic or mildly symptomatic COVID-19 between 27 January and 11 March 2020 and described the recovery situation after discharge at the 6–8-month revisit. Knowledge of the durability of the initial immune response and the protective capacity of immune memory will provide references for the protection for children and provide a basis for future vaccine development for children
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