Long-Term Persistence of SARS-CoV-2 Neutralizing Antibody Responses After Infection and Estimates of the Duration of Protection

The duration of immunity in SARS-CoV-2 infected people remains unclear. Neutralizing antibody responses are the best available correlate protection against re-infection. Recent studies have estimated that 50% from re-infection was 20% mean convalescent neutralizing titre. We used sera collected a cohort 125 individuals with RT-PCR confirmed infections up to 386 days after symptom onset. In subset 65 day 151 onset, all remained positive plaque reduction neutralization tests (PRNT50). Because waning follows bimodal pattern slower beyond 90 illness, we fitted lines decay 115 62 patients onset and estimate PRNT50 will remain detectable for around 1,717 protective titers be maintained 990 post-symptom symptomatic patients. Peak PRNT titres mildly children did not differ those adults but these appear wane faster children. There high level correlation between % inhibition surrogate virus tests. conclude there relatively long-lived following COVID-19 disease. Funding Information: study supported by Health Medical Research Fund, Commissioned research on Novel Coronavirus Disease (COVID-19) (Reference no COVID190126) Food Bureau, Hong Kong SAR Government Theme-based Scheme project no. T11-712/19-N, University Grants Committee Government. Declaration Interests: None authors any conflicts interest declare. Ethics Approval Statement: Written informed consent obtained participants or their parents (when participant child) were approved institutional review boards respective hospitals, viz. Kowloon West Cluster (KW/EX-20-039 (144-27)), Central / East cluster (KC/KE-20-0154/ER2) HKU/HA (UW 20-273).