  The quantum spin Hall state can be understood in terms of spontaneous O(3)
symmetry breaking. Topological skyrmion configurations of the O(3) order
parameter vector carry a charge 2e, and as shown previously, when they
condense, a superconducting state is generated. We show that this topological
route to superconductivity survives easy-plane anisotropy. Upon reducing the
O(3) symmetry to O(2)$\times$ Z$_2$, skyrmions give way to merons that carry a
unit charge. On the basis of large-scale auxiliary field quantum Monte Carlo
simulations, we show that at the particle-hole symmetric point, we can trigger
a continuous and direct transition between the quantum spin Hall state and
s-wave superconductor by condensing pairs of merons. This statement is valid in
both strong and weak anisotropy limits. Our results can be interpreted in terms
of an easy-plane deconfined quantum critical point. However, in contrast to the
previous studies in quantum spin models, our realization of this quantum
critical point conserves $U(1)$ charge, such that skyrmions are conserved.
