Before revision:  Nested case-control analysis of 18,814 pairs of hospitalised/non-hospitalised patients, one-to-one matched on age, sex, ethnicity, deprivation, region of residence, and date of positive test (matches found for 96.6\%).
After revision:  Patient data were stratified by age, sex, ethnicity, deprivation, region of residence, and date of positive test (matches found for 96.6\%).