The data in the QR code of the COVID certificate are electronically signed. This allows the checking apps (in Switzerland the COVID Certificate Check app) to verify that the certificate presented is genuine and that the information it contains has not been manipulated since it was issued.
The COVID certificate itself is thus protected from being altered and is linked personally to the holder. When your personal COVID certificate is checked, you must therefore show a photo ID (for example your identity card or passport).
It is not possible from a technical point of view for the federal government to monitor whether correct information is used for issuing COVID certificates. This is the responsibility of the issuers in each case. COVID certificates can only be issued by authorised personnel at vaccination centres, medical practices, hospitals, pharmacies and laboratories, as well as by cantonal authorities. Supervision of authorised issuers lies with the cantons.