A 32-year-old healthcare worker has a needlestick injury from a source patient known to be Hepatitis B surface antigen (HBsAg) positive. The healthcare worker completed a full course of Hepatitis B vaccination 5 years ago and their anti-HBs level checked last year was >100 mIU/mL. According to UK Health Security Agency (UKHSA) guidelines ('Green Book'), what is the appropriate post-exposure prophylaxis?