I will discuss the first construction of coherent states (and other massive states with arbitrarily exited harmonics) 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, highlighting the virtues and shortcomings of each. 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.