Extended Data Fig. 5: Comparison of monthly counts of dispensed CVD medications, by linkage status. ‘Unlinked’ category includes medications dispensed with invalid (‘null’) ID.

Null IDs may arise from a variety of reasons, including, but not limited to: problems scanning the NHS number from paper prescriptions, non-availability of date of birth for data linkage, removal of NHS ID from some sensitive medication. Vertical dotted lines indicate the timing of the first, second and third national lockdowns on 26^th March 2020, 5^th November 2020 and 6^th January 2021, respectively.