Follow-up of children diagnosed with severe asthma before and during the COVID-19 pandemic

During the COVID-19 pandemic, health care strategies were explored to ensure the follow-up of children with severe asthma. This was a prospective, observational, and comparative study. Patients in the severe asthma program of a tertiary care children's hospital were included (n: 74). The extent of control, exacerbations, and hospitalizations during an in-person period (IPP) (March 2019-2020) and an online period (OP) (April 2020-2021) was assessed. A total of 74 patients were enrolled in the IPP compared to 68 (92%) in the OP. During the IPP, 68% (46) of patients had exacerbations versus 46% (31) during the OP (p = 0.003). During the IPP, 135 total exacerbations were recorded compared to 79 during the OP (p = 0.001); this accounted for a 41% reduction. During the IPP, 47% (32) of patients had severe exacerbations versus 32% (22) during the OP (p = 0.048). A total of 91 severe exacerbations were recorded during the IPP compared to 49 during the OP (p = 0.029); the reduction was 46%. No differences were observed in terms of hospitalization (IPP: 10, OP: 6; p = 0,9). Telemedicine was effective for the follow-up of patients with severe asthma.

Clinical Utility of SARS-CoV-2 Antibody Titer Multiplied by Binding Avidity of Receptor-Binding Domain (RBD) in Monitoring Protective Immunity and Clinical Severity

Conventional serum antibody titer, which expresses antibody level, does not provide antigen binding avidity of the variable region of the antibody, which is essential for the defense response to infection. Here, we quantified anti-SARS-CoV-2 antibody binding avidity to the receptor-binding domain (RBD) by competitive binding-inhibition activity (IC50) between SARS-CoV-2 S1 antigen immobilized on the DCP microarray and various RBD doses added to serum and expressed as 1/IC50 nM. The binding avidity analyzed under equilibrium conditions of antigen-antibody binding reaction is different from the avidity index measured with the chaotropic agent, such as urea, under nonequilibrium and short-time conditions. Quantitative determination of the infection-protection potential of antibodies was assessed by ABAT (antigen binding avidity antibody titer), which was calculated by the quantity (level) × quality (binding avidity) of antibodies. The binding avidity correlated strongly (r = 0.811) with cell-based virus-neutralizing activity. Maturation of the protective antibody induced by repeated vaccinations or SARS-CoV-2 infection was classified into three categories of ABAT, such as an initial, low, and high ABAT. Antibody maturity correlated with the clinical severity of COVID-19. Once a mature high binding avidity was achieved, it was maintained for at least 6-8 months regardless of the subsequent change in the antibody levels.