  Several long-standing anomalies from short-baseline neutrino oscillation
experiments -- most recently corroborated by new data from MiniBooNE -- have
led to the hypothesis that extra, 'sterile', neutrino species might exist.
Models of this type face severe cosmological constraints, and several ideas
have been proposed to avoid these constraints. Among the most widely discussed
ones are models with so-called 'secret interactions' in the neutrino sector. In
these models, sterile neutrinos are hypothesized to couple to a new
interaction, which dynamically suppresses their production in the early
Universe through finite-temperature effects. Recently, it has been argued that
the original calculations demonstrating the viability of this scenario need to
be refined. Here, we update our earlier results from arXiv:1310.6337 [JCAP 1510
(2015) no.10, 011] accordingly. We confirm that much of the previously open
parameter space for secret interactions is in fact ruled out by cosmological
constraints on the sum of neutrino masses and on free-streaming of active
neutrinos. We then discuss possible modifications of the vanilla scenario that
would reconcile sterile neutrinos with cosmology.
