  A perfectly reflecting (Dirichlet) boundary condition at the edge of an
impenetrable magnetic-flux-carrying tube of nonzero transverse size is imposed
on the charged massive scalar matter field which is quantized outside the tube
on a plane which is transverse to the tube. We show that the vacuum
polarization effects outside the tube give rise to a macroscopic force acting
at the increase of the tube radius (if the magnetic flux is held steady).
