No colds or flu in a little over 2 years of vaping ... 
When I did get the early warnings of a cold, the slightly scratchy throat and mild congestion, it passed by the next morning. Before that, when smoking, that would lead to a week or two of utter misery ...
That was in the first year of vaping ...
Since then, I retired and no longer spend my days in a "sick" building, half filled with contagious jerks who won't use vacation days, and who cough and sneeze openly with total disregard for others, into the stale recirculated air ...
It seems to be common now for office buildings to have fixed windows, and all but one front door locked, sometimes chained, for "security". These buildings were designed to "breathe", with all doors opened and closed randomly throughout the day, allowing the intake of fresh air ...
Haven't even had a tickle in the throat for the past year, since I escaped the Petri dish of a sealed office structure ...

When I did get the early warnings of a cold, the slightly scratchy throat and mild congestion, it passed by the next morning. Before that, when smoking, that would lead to a week or two of utter misery ...
That was in the first year of vaping ...
Since then, I retired and no longer spend my days in a "sick" building, half filled with contagious jerks who won't use vacation days, and who cough and sneeze openly with total disregard for others, into the stale recirculated air ...
It seems to be common now for office buildings to have fixed windows, and all but one front door locked, sometimes chained, for "security". These buildings were designed to "breathe", with all doors opened and closed randomly throughout the day, allowing the intake of fresh air ...
Haven't even had a tickle in the throat for the past year, since I escaped the Petri dish of a sealed office structure ...