ABSTRACT Uncertainty exists whether mild COVID-19 confers immunity to reinfection. Questions also remain regarding the persistence of antibodies against SARS-CoV-2 after mild infection. We prospectively followed at-risk individuals with and without SARS-CoV-2 for reinfection and monitored the spike and nucleocapsid antibodies. This prospective cohort study was conducted over two visits, 3 to 6 months apart, between May 2020 and February 2021. Adults with and without COVID-19, verified by FDA EUA-approved SARS-CoV-2 RT-PCR assays, were screened for spike and nucleocapsid antibody responses using FDA EUA-approved immunoassays and for pseudoviral neutralization activity. The subjects were monitored for symptoms, exposure to COVID-19, COVID-19 testing, seroconversion, reinfection, and vaccination. A total of 653 subjects enrolled; 129 (20%) had a history of COVID-19 verified by RT-PCR at enrollment. Most had mild disease, with only three requiring hospitalization. No initially seropositive subjects experienced a subsequent COVID-19 infection during the follow-up versus 15 infections among initially seronegative subjects (infection rates of 0.00 versus 2.05 per 10,000 days at risk [ P = 0.0485]). In all, 90% of SARS-CoV-2-positive subjects produced spike and nucleocapsid responses, and all but one of these had persistent antibody levels at follow-up. Pseudoviral neutralization activity was widespread among participants, did not decrease over time, and correlated with clinical antibody assays. Reinfection with SARS-CoV-2 was not observed among individuals with mild clinical COVID-19, while infections continued in a group without known prior infection. Spike and nucleocapsid COVID-19 antibodies were associated with almost all infections and persisted at stable levels for the study duration. IMPORTANCE This article demonstrates that people who have mild COVID-19 illnesses and produce antibodies are protected from reinfection for up to 6 months afterward. The antibodies that people produce in this situation are stable for up to 6 months as well. Clinical antibody assays correlate well with evidence of antibody-related viral neutralization activity.
【저자키워드】 COVID-19, SARS-CoV-2, Vaccine, Immunity, spike, serology, antibody, nucleocapsid, persistence, viral neutralization, immunoserology, pseudoviral neutralization, 【초록키워드】 antibodies, vaccination, Hospitalization, antibody, Antibody Response, Infection, risk, prospective cohort study, RT-PCR, FDA, Symptoms, immunoassays, immunoassay, Reinfection, COVID-19 testing, Seroconversion, Viral, COVID-19 infection, clinical, Mild, Follow-up, COVID-19 antibody, SARS-CoV-2 RT-PCR, antibody assay, Uncertainty, disease, seronegative, Mild disease, Antibody assays, mild infection, Evidence, evidence of, exposure to, study duration, Participants, Enrollment, subject, infection rates, individual, neutralization activity, RT-PCR assays, MOST, nucleocapsid responses, widespread, decrease, produced, assays, subsequent, conducted, screened, correlated, illness, seropositive subject, 【제목키워드】 persistent, illness,