Missing whitespace in LaTeX display of monomials with long variable names

[epatters]

Consider the display of the mass-action equations for a Petri net built compositionally:

The term with Unvax.I multiplied by Unvax.S has no space or operation in between them. Viable options include

\text{Unvax.I}\, \text{Unvax.S} % whitespace

or

\text{Unvax.I} \cdot \text{Unvax.S} % explicit multiplication symbol