Aerosol Formation During Processing of Potentially Infectious Samples on Roche Immunochemistry Analyzers (cobas e analyzers) and in an End-to-End Laboratory Workflow to Model SARS-CoV-2 Infection Risk for Laboratory Operators

Background This study assessed formation of potentially infectious aerosols during processing of infectious samples in a real-world laboratory setting, which could then be applied in the context of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods This two-part study assessed aerosol formation when using cobas e analyzers only and in an end-to-end laboratory workflow. To estimate aerosol formation, recombinant hepatitis B surface antigen (HBsAg) was used as a surrogate marker for infectious virus particles to evaluate the potential risk of SARS-CoV-2 infection to laboratory operators. Using the HBsAg model, air sampling was performed at different positions around the cobas e analyzers and in four scenarios reflecting critical handling and/or transport locations in an end-to-end laboratory workflow. Aerosol formation of HBsAg was quantified using the Elecsys ® HBsAg II quant II assay. The model was then applied to a SARS-CoV-2 context using SARS-CoV-2 infection-specific parameters to calculate viral RNA copies. Results Following application to SARS-CoV-2, the mean HBsAg uptake per hour when recalculated into viral RNA copies was 1.9 viral RNA copies across the cobas e analyzers and 0.87 viral RNA copies across all tested scenarios in an end-to-end laboratory workflow. This corresponds to a maximum aspiration rate of <16 viral RNA copies during an 8-hour shift when using cobas e analyzers and/or in an end-to-end laboratory workflow. Conclusions The low production of marker-containing aerosol when using cobas e analyzers and in an end-to-end laboratory workflow is consistent with a remote risk of laboratory-acquired SARS-CoV-2 infection for laboratory operators. Summary This study investigated the formation of potentially infectious aerosols during processing of infectious samples in a model using hepatitis B surface antigen (HBsAg) as a marker for infectious virus particles. The risk to laboratory operators of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was then inferred. Air sampling was performed around cobas e analyzers and in an end-to-end laboratory workflow, after which HBsAg was quantified and applied to SARS-CoV-2 using SARS-CoV-2 infection-specific parameters. The maximum aspiration rate of <16 viral RNA copies/8-hour shift, when applied to a SARS-CoV-2 context, poses a remote risk of SARS-CoV-2 infection to laboratory operators.