ABSTRACT
BACKGROUND: SARS-CoV-2 infection in children does not seem to follow the same pattern as in adults. Limited information is published on the level of antibody production and the duration of antibody response in children with COVID-19. Moreover, it is unknown if all children have a similar immune response to the infection, or if there are age dependent differences. In these data, we look at the IgM and IgG levels and duration of two age groups infected by the SARS-CoV-2 virus. METHODS: Residual laboratory specimens from pediatric patients positive for SARS-CoV-2 infection were tested for IgM and IgG against SARS-CoV-2 using an automated Abbott ARCHITECT i1000. We tested 181 specimens from 41 patients with a positive molecular result. Data was grouped either as time after nucleic acid amplification test (NAAT) or time after symptom onset. Patient samples were divided into 2 age groups: 0 to 11 years old and 12 to 19 years old. The assays detect IgM against the spike protein and IgG against the nucleocapsid protein.
ABSTRACT
BACKGROUND: Clinical laboratory testing has been an essential part of COVID-19 management. Serology can provide valuable information regarding a patient's exposure to virus, and may have a larger role to play as vaccines becomes available. Limited data is available on the serological response in pediatric patients. Here we investigate the use of one manufacturer's commercial assays for detecting IgM and IgG in an exclusively pediatric population. METHODS: Abbott SARS-CoV-2 IgM and IgG assays were performed on an Abbott ARCHITECT i1000. For specificity studies, we tested 78 patient specimens collected before the COVID-19 pandemic, and 66 specimens from patients who tested negative for SARS-CoV-2 nucleic acid amplification test (NAAT) during the COVID-19 pandemic. For sensitivity we tested 181 specimens from 41 patients with a positive NAAT result. Precision data was acquired for 20 days. RESULTS: For IgM, the highest qualitative positive agreement with molecular results was observed to be 15-30 days after a positive NAAT result or after symptom onset. For IgG, the highest positive agreement was 31-60 days after a positive NAAT result or 61-90 days after the start of symptoms. IgM started to decline 30 days after NAAT results and faded by 90 days. IgG started to decrease 60 days after a positive NAAT result. CONCLUSION: The Abbott IgM and IgG assays have negative agreements of 98.7-100% relative to NAAT results. The IgM and IgG levels assayed by these methods start to decline months after positive molecular results and onset of symptoms in a pediatric population.
ABSTRACT
Measurement of measles virus-specific IgG is used to assess presumptive evidence of immunity among immunocompetent individuals with uncertain immune or vaccination status. False-negative test results may lead to unnecessary quarantine and exclusion from activities such as employment, education, and travel or result in unnecessary revaccination. In contrast, false-positive results may fail to identify susceptible individuals and promote spread of disease by those who are exposed and unprotected. To better understand the performance characteristics of tests to detect measles IgG, we compared five widely used, commercially available measles IgG test platforms using a set of 223 well-characterized serum samples. Measles virus neutralizing antibodies were also measured by in vitro plaque reduction neutralization, the gold standard method, and compared to IgG test results. Discrepant results were observed for samples in the low-positive ranges of the most sensitive tests, but there was good agreement across platforms for IgG-negative sera and for samples with intermediate to high levels of IgG. False-negative test results occurred in approximately 11% of sera, which had low levels of neutralizing antibody.
