Clinical immunity in discharged medical patients with COVID-19

Background: Most studies on SARS-CoV-2 infection show that people who have recovered from COVID-19 have antibodies to the virus. No study has evaluated whether the presence of antibodies to SARS-CoV-2 confers immunity to the infection relapse but however, to date, no human reinfections with SARS-CoV-2 have been confirmed. Material and methods: In our prospective, multicenter, cohort study we investigated within three months all patients, with confirmed COVID-19, discharged from two Hospitals (Legnano and Magenta Hospitals), in an area of Italy severely affected by the infection. Telephone follow-up at 1 and 2 months and clinical contact within 3 months was initiated; demographic, clinical, radiologic and laboratory data were recorded in electronic medical records and updated. Results: Of 1081 patients involved, 804 (74.3%) were discharged alive. For all these patients we obtained follow-up data. At 1 and 2 months none has died and none has had any signs of recurrence of infectious at both telephone interview and clinical visit. Conclusion: Our clinical observation have confirmed two basic points: the reinfection is very unlikely and any antibody immunity protects against recurrence, at least in the short term. (C) 2020 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.