Testing speed is the key factor in controlling the spread of the coronavirus, according to a new study in The Lancet Public Health journal released Thursday. The study showed that a three-day delay in testing following the onset of COVID-19 symptoms stops the efficacy of contact tracing in reducing viral transmission. For contact tracing to be effective, test results must be reported within one day of symptom onset, the study said. Researchers also found that while mobile contact tracing apps improve contact tracing speed, they are not effective in limiting transmission when test results are delayed. The study comes as patients are seeing lengthy wait times for test results amid a massive surge in cases across the country. Quest Diagnostics, a medical laboratory company and major player in coronavirus testing, announced Monday that test results for non-priority patients take an average of seven days to report.