Factors affecting turnaround time of SARS-CoV-2 sequencing for inpatient infection prevention and control decision making: Analysis of data from the COG-UK HOCI study

Background Barriers to rapid return of sequencing results can affect the utility of sequence data for infection prevention and control decisions. Aim To undertake a mixed-methods analysis to identify challenges sites faced in achieving a rapid turnaround time (TAT) in the COG-UK Hospital-Onset COVID-19 Infection (COG-UK HOCI) study. Methods For the quantitative analysis, timepoints relating to different stages of the sequencing process were extracted from both the COG-UK HOCI dataset and surveys of study sites. Qualitative data relating to the barriers and facilitators to achieving rapid TAT were included from thematic analysis. Findings The overall TAT, from sample collection to receipt of sequence report by infection control teams, varied between sites (median 5.1 days, range 3.0 – 29.0 days). Most variation was seen between reporting of a positive COVID-19 PCR result to sequence report generation (median 4.0 days, range 2.3 – 27.0 days). On deeper analysis, most of this variability was accounted for by differences in the delay between the COVID-19 PCR result and arrival of the sample at the sequencing laboratory (median 20.8 hours, 16.0 – 88.7 hours). Qualitative analyses suggest closer proximity of sequencing labs to diagnostic labs, increased staff flexibility and regular transport times facilitated a shorter TAT. Conclusion Integration of pathogen sequencing into diagnostic laboratories may help improve sequencing TAT to allow sequence data to be of tangible value to infection control practice. Adding a quality control step upstream to increase capacity further down the workflow may also optimise TAT if lower quality samples are removed earlier on