Fig. 5. Results of linear regression models with N-gene Ct values as the outcome variable and symptoms as individual predictors, adjusted for age, sex and, where appropriate, vaccination status, among N = 10,709 swab-positive respondents in rounds 17–19 (5 January to 31 March 2022).

Error bars show 95% confidence intervals. Fever, chills, and sore throat are the symptoms with the strongest negative association with Ct value, each associated with approximately a tenfold increase in viral load.