Frequent detection but lack of infectivity of SARS-CoV-2 RNA in presymptomatic, infected blood donor plasma

Respiratory viruses such as influenza do not typically cause viremia; however, SARS-CoV-2 has been detected in the blood of COVID-19 patients with mild and severe symptoms. Detection of SARS-CoV-2 in blood raises questions about its role in pathogenesis as well as transfusion safety concerns. Blood donor reports of symptoms or a diagnosis of COVID-19 after donation (post-donation information, PDI) preceded or coincided with increased general population COVID-19 mortality. Plasma samples from 2,250 blood donors who reported possible COVID-19-related PDI were tested for the presence of SARSCoV-2 RNA. Detection of RNAemia peaked at 9%-15% of PDI donors in late 2020 to early 2021 and fell to approximately 4% after implementation of widespread vaccination in the population. RNAemic donors were 1.2- to 1.4-fold more likely to report cough or shortness of breath and 1.8-fold more likely to report change in taste or smell compared with infected donors without detectable RNAemia. No infectious virus was detected in plasma from RNAemic donors; inoculation of permissive cell lines produced less than 0.7-7 plaque-forming units (PFU)/mL and in susceptible mice less than 100 PFU/mL in RNA-positive plasma based on limits of detection in these models. These findings suggest that blood transfusions are highly unlikely to transmit SARS-CoV-2 infection.

Automated summary

Unlike respiratory viruses such as influenza, SARS-CoV-2 can be detected in the blood of COVID-19 patients. Reports of COVID-19 symptoms or diagnosis after blood donation were associated with increased mortality in the general population. The detection rate of RNAemia in blood donors with possible COVID-19-related post-donation information (PDI) reached 9%-15% in late 2020 to early 2021 and decreased to approximately 4% after widespread vaccination. Donors with RNAemia were more likely to report cough, shortness of breath, change in taste, or smell compared to infected donors without detectable RNAemia. No infectious virus was found in plasma samples, indicating a minimal risk of transmitting SARS-CoV-2 through blood transfusions.