"Methods: The Real-time Assessment of Community Transmission–1 (REACT-1) study has been tracking the spread of the COVID-19 pandemic in England since May 2020. The study involves obtaining a self-administered throat and nose swab for reverse transcription polymerase chain reaction (RT-PCR) from ~100,000 or more people during 2 to 3 weeks each month, based on random samples of the population in England at ages 5 years and above...
Cycle threshold values: We analyzed Ct [cycle threshold] values associated with positive results among vaccinated and unvaccinated individuals as a measure of viral load. For all positives in round 13, at ages 18 to 64 years, median Ct value for vaccinated participants [27.6 (CI for median, 25.5, 29.7)] was higher than for unvaccinated ones [23.1 (CI 20.3, 25.8)."
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