Vacuum packed sausage that is raw or cooked does need to be refrigerated if it's not cured sausage.
The vacuum packaging does not prevent the spoilage of the sausage and so it must be kept refrigerated or it will go bad unless it's a cured sausage.
Vacuum Packed sausage lasts from 5 to 7 days in the refrigerator or 6 months to a year in the freezer.
Perishable (whether it is raw or cooked) meats and poultry in vacuum packaging cannot be stored at room temperature.
They must be kept either in the refrigerator at 40 ºF or below, or for longer storage, in the freezer at 0 °F or below.
Smoked sausage that has been dried and cured can be left out overnight.
However regular smoked sausage that has not been dried or cured should not be left out overnight as it can go bad.
Dry-cured smoked sausage may be left out overnight depending on the manufacturer and meat type, but smoked sausage that hasn't been cured or preserved should be kept in the fridge or freezer.
Always follow the packaging's storage instructions, as not all smoked sausage is created equally.
Smoked sausage that has not been cured can be left out at room temperature for up to 2 hours.
After 2 hours the smoked sausage could contain bacteria and should be thrown out.
The dried and cured smoked sausage can be left out longer.
According to the USDA, you can keep dry cured sausage in the pantry for up to six weeks.
Also according to USDA guidance, all other types of sausages that should be refrigerated should be thrown out after 2 hours at room temperature or the 'danger zone' between 40-140 °F.
Although the sell-by date isn't an expiration date, smoked sausage doesn't "live" forever.
Generally, use it within two weeks before the package is opened or one week after opening.
Frozen sausage stays safe practically indefinitely, although the USDA recommends using it within one to two months for quality reasons.