and the parent or guardian of every unprotected child may, whenever the Superintendent of Vaccination, as hereinafter appointed, shall deem it expedient, be served with a notice, in the form prescribed in the first schedule of this Act, requiring the parent or guardian, within fifteen days after the service of the same, to take such child, or cause such child to be taken, to a public vaccine-station to be vaccinated, or within such period as aforesaid to cause it to be vaccinated by some medical practitioner or public vaccinator;