You are the duty doctor at your GP surgery. A 22 year old university student calls to speak with you with concerns about having contracted HIV. He admits having unprotected intercourse with a new male partner 5 days ago and having received oral and anal sex. He denies any dysuria, urethral discharge, genital warts or ulcers. You agree that a full sexual health screen is sensible and advise him to attend the local sexual health clinic later today. You discuss the significance of the ‘window period’ in HIV testing.
Which one of the following statements regarding HIV testing is most correct?