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Persistence of neutralizing antibodies and clinical protection up to 12 months after SARS-CoV-2 infection in elderly. Open Forum Infect Dis 2022; 9:ofac613. [DOI: 10.1093/ofid/ofac613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/09/2022] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
COVID-19 has severely affected the elderly who are expected to display decreased immune responses due to immunosenescence.
Methods
This study retrospectively assesses neutralizing antibodies (NAb) productions up to 12 months(M) after infection in Long-term care patients. We used Roche diagnostics immunoassay to quantify anti-Spike(S) antibodies and a competitive immunoassay from Yhlo as a surrogate test for NAb.
Results
We included 91 patients, mean age 86 years. There was no significant variation of anti-S titers over time. There was a significant decrease of NAb titers between M3 and M6 but no further significant change up to M12. Overall, 75/91 (82%) and 52/91 (57%) patients had at least once anti-S titers >75 U/mL and NAb titers >50 AU/mL, respectively, corresponding to a significant neutralizing activity in vitro. All 68 patients studied at M12 had detectable anti-S antibodies and 60 (88%) had detectable NAb; 60/68 (88%) and 29/68 (42.6%) still had anti-S titers >75 U/mL and NAb titers >50 AU/mL. Higher NAb titers were correlated with severe infection, higher levels of CRP and lower lymphocyte counts. No patient developed reinfection.
Conclusion
Elderly people can display robust and persistent humoral response after SARS-CoV-2 infection, with NAb lasts up to 12 months.
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