Could the computer that holds all this information be hacked or data about me be leaked in some way?

Public Health England knows that many people are concerned about the security of data collections and therefore applies the strongest form of encryption to the data they hold.  Data about your health is highly sensitive, and so great care is taken over the way it is collected, stored, and analysed. There is also an obligation to the National Data Guardian to ensure all sensitive data is strongly encrypted and stored on NHS compliant secure servers. The information is only accessible by staff who have been vetted and operate under the strictest of controls. Security procedures are regularly reviewed to make sure that all systems use the most up to date and effective ways to protect the data about you.