12.—(1) If she decides to undertake a programme of protective vaccination, the Secretary of State shall at the same time declare any place or geographical area where it is to be undertaken to be a vaccination zone and shall also declare a vaccination surveillance zone.
(2) A declaration under paragraph (1) shall designate—
(a)the extent of the vaccination zone; and
(b)the extent of the vaccination surveillance zone.
(3) A vaccination surveillance zone declared under paragraph (1) shall extend from the vaccination zone for at least ten kilometres and otherwise shall be of such size as the Secretary of State considers fit to prevent the spread of disease.
(4) If she decides to vary the place or geographical area where a programme of protective vaccination is to be undertaken, the Secretary of State shall amend the declaration under paragraph (1) so that the vaccination zone comprises the place or geographical area as varied.