Long-term clinical and serological follow-up of paediatric patients infected by SARS-CoV-2

Studies concerning Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection in paediatrics are limited to children mainly selected from hospitals, where patients with complications and co-morbidities are managed. We aimed to describe the course of the Coronavirus Disease 2019 (COVID-19) in a population of children enrolled by place of residence, from diagnosis to recovery, with a long-term clinical and serological follow-up. We identified patients aged <14 years old living in the Turin Health District 3 who had SARS-CoV-2 detected in at least one nasopharyngeal swab from 1st March to 1st June 2020. Epidemiological and clinical features of SARS-CoV-2 infection were collected by way of a telephone inquiry. Enrolled patients were tested for SARS-CoV-2 serology in order to provide evidence of seroconversion and persistence of specific antibodies some time after the infection. A total of 46 patients with SARS-CoV-2 infection/COVID-19 were identified. The main pattern of viral transmission was intra-family. Eleven children were totally asymptomatic. If symptoms appeared, the disease had a mild course. A single case of COVID-19-related respiratory insufficiency was registered. Among children who underwent serological evaluation, 84% had seroconversion. No significant differences in antibody development were found according to the age and the burden of the disease. Children tested farther from the primary infection had lower antibody index titre values than the others. In conclusion, COVID-19 has a good prognosis in paediatric age. Children are able to develop a valid immune response, although their index titres seem to decrease a long time after the disease.