  A screening mechanism for conformal vector-tensor modifications of general
relativity is proposed. The conformal factor depends on the norm of the vector
field and makes the field to vanish in high dense regions, whereas drives it to
a non-null value in low density environments. Such process occurs due to a
spontaneous symmetry breaking mechanism and gives rise to both the screening of
fifth forces as well as Lorentz violations. The cosmology and local constraints
are also computed.
