Investigation of SARS-CoV-2 RNAemia in the convalescent plasma of COVID-19 patients

Purpose: The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is responsible for the ongoing global COVID-19 disease pandemic. Convalescent plasma therapy (CPT) is one of the promising therapies being tried for COVID-19 patients. However, the presence or disappearance of SARS-CoV-2 RNA (RNAemia) in convalescent plasma is unclear and the prognostic implication of viral RNA detection in these samples is not fully understood. Hence, we aimed to investigate SARS-CoV-2 RNAemia in the convalescent plasma of COVID-19 patients. Methods & Materials: Convalescent plasma samples from donors with a previous laboratory-confirmed SARS-CoV-2 infection were included in the study. Samples were screened for the presence of Anti-SARS CoV-2 IgG antibodies using a commercially available enzyme-linked immunosorbent assay targeting the whole-cell antigen of SARS-CoV-2. Then plasma samples were pooled by the mixing of five samples. RNA extraction and real-time RT-PCR for SARS-CoV-2 specific gene targets was performed for pooled plasma samples. Results: A total of 250 convalescent plasma samples of COVID-19 patients with different disease severity were included in the study; of these, 149 (59.6%) were found to have anti-SARS-CoV-2 antibodies using serological tests. SARS-CoV-2 RNA was not detected in any of the convalescent plasma samples. Conclusion: SARS-CoV-2 RNAemia was not found in individuals with a previous laboratory-confirmed SARS-CoV-2 infection at least 28 days after the resolution of their symptoms. All RT-PCR positive COVID-19 patients subsequently may not develop antibodies. Our study showed that screening for neutralizing antibody titres is more important rather than SARS-CoV-2 RNA detection in convalescent plasma samples for therapeutic use.