What i do know for sure is that when i was twelve years old, in the middle of a mumps outbreak, i was vaccinated for mumps. That was in 1960 or 56 years ago. I immediately came down with not just mumps but double pneumonia and survived by the skin of my teeth and a three month loss of school time.
What passed then for vaccine was clearly unsatisfactory and this has actually held true ever since. There is even serious doubt that it works at all and actually public fear and responsive parents likely does the most to suppress the disease.
Mumps is a nasty lung based bacterial infection that is difficult to flush out of your system. I had an encounter decades later that took about a month to eliminate. However, given time and good care, your immune system will clean it up. Do not ever combine with smoking and dusty environments.