Kinetics of viral clearance and antibody production across age groups in SARS-CoV-2 infected children

Objectives: To improve understanding of transition from viral infection to viral clearance, and antibody response in pediatric patients with SARS-CoV-2 infection. Study design: This retrospective analysis of children tested for SARS-CoV-2 by RT-PCR and IgG antibody at a quaternary-care, free-standing pediatric hospital between March 13th, 2020 to June 21st, 2020 included 6369 patients who underwent PCR testing and 215 patients who underwent antibody testing. During the initial study period, testing focused primarily on symptomatic children; the later study period included asymptomatic patients who underwent testing as preadmission or preprocedural screening. We report the proportion of positive and negative tests, time to viral clearance, and time to seropositivity. Results: The rate of positivity varied over time due to viral circulation in the community and transition from targeted testing of symptomatic patients to more universal screening of hospitalized patients. Median duration of viral shedding (RT-PCR positivity) was 19.5 days and RT-PCR negativity from positivity was 25 days. Of note, patients aged 6 to 15 years demonstrated a longer period of RT-PCR negativity from positivity, compared to patients aged 16 to 22 years (median=32 versus 18 days, p=0.015). Median time to seropositivity from RT-PCR positivity was 18 days while median time to reach adequate levels of neutralizing antibodies (defined as equivalent to 160 titer) was 36 days. Conclusions: The majority of patients demonstrated a prolonged period of viral shedding after infection with SARS CoV-2. Whether this correlates with persistent infectivity is unknown. Only 17 of 33 patients demonstrated neutralizing antibodies, suggesting that some patients may not mount significant immune responses to infection. It remains unknown if IgG antibody production correlates with immunity and how long measurable antibodies persist and protect against future infection.