  The effects originated in dispersion with time on spreading of wave packets
for the time-integrated two-flavor neutrino oscillation probabilities in vacuum
are studied in the context of a field theory treatment. The neutrino flavor
states are written as superpositions of neutrino mass eigenstates which are
described by localized wave packets. This study is performed for the limit of
nearly degenerate masses and considering an expansion of the energy until third
order in the momentum. We obtain that the time-integrated neutrino oscillation
probabilities are suppressed by a factor $1/L^2$ for the transversal and
longitudinal dispersion regimes, where $L$ is the distance between the neutrino
source and the detector.
