How long can refrigerated inactive vaccines last outside?

Hard to say: Some vaccines are less stable than others.

Varies: The last time I checked on the common ones I give it wad a full day for most. I found that surprising but that was a discussion we had with the manufacturer. The caveat was they only looked at stability for an air conditioned office environment.They could not comment about exposures.They routinely have us return vaccine that got warm at any point during shipping (they have that technology)