I will discuss the first construction of coherent states in the covariant formalism for both open and closed strings with applications to cosmic strings in mind. Furthermore, I provide an explicit map that relates three different descriptions of cosmic strings: classical strings, lightcone gauge quantum states and covariant vertex operators. I will then go on to discuss applications and future directions: string amplitude computations with such vertices and in particular decays of (the phenomenologically promising) cosmic strings with non-degenerate cusps in a framework that naturally incorporates the effects of gravitational backreaction. Partly based on: http://arxiv.org/abs/0911.5354