  We update lattice QCD results for second order cumulants of conserved charge
fluctuations and correlations at non-zero temperature and vanishing values of
the conserved charge chemical potentials. We compare these results to hadron
resonance gas calculations with and without excluded volume terms as well as
S-matrix results in the hadronic phase of QCD, and comment on their current
limitations. We, furthermore, use these results to characterize thermal
conditions in the vicinity of the pseudo-critical line of the chiral transition
in QCD. We argue that the ratio of strange to baryon chemical potentials is a
robust observable that, on the one hand, deviates only little from hadron
resonance gas results, but, on the other hand, is very sensitive to the
spectrum of strange baryon resonances.
