Do flu shots prevent intestinal flu or do they just prevent the cold flu?
The flu shot only prevents respiratory influenza. It does not
prevent the gastrointestinal "flu" virus that makes you have GI
symptoms like nausea, vomiting, and diarrhea without the cough and
respiratory symptoms of influenza. The flu that makes you throw up
is not really influenza, it is just an illness that is also caused
by a virus or "bug" (called viral gastroenteritis).
True seasonal respiratory influenza, on the other hand, if bad
enough (or if you are very young or over 65) is more likely to
cause severe complications or even death. The stomach virus usually
doesn't result in the same severity, as long as dehydration is
controlled by drinking plenty of liquids (and perhaps an occasional
sports drink to replenish electrolytes like sodium, potassium, and
The shots you get for seasonal influenza, and the flu vaccine to
prevent the A-H1N1/09 "Swine Flu", are made for protection against
respiratory influenza, not for the "stomach flu".
Fun facts: The intestinal flu is not really the flu. It has been
incorrectly called that for a long time, but is actually called
gastroenteritis and usually is caused by viral infections but might
also be bacterial. Influenza (flu) is a respiratory disease that
only rarely causes any gastrointestinal symptoms. A very common
viral gastroenteritis is what most people call stomach flu, or they
also call it Norwalk flu and is caused by a norovirus.
"Norovirus (formerly Norwalk agent) is an RNA virus (taxonomic
family Caliciviridae) that causes approximately 90% of epidemic
nonbacterial outbreaks of gastroenteritis around the world, and may
be responsible for 50% of all foodborne outbreaks of
gastroenteritis in the US. Norovirus affects people of all ages.
The viruses are transmitted by fecally contaminated food or water,
by person-to-person contact,and via aerosolization of the virus and
subsequent contamination of surfaces."