How come I got flu despite having my flu shot?
We tend to confuse common cold and flu together. Common cold describes many upper respiratory ailments. They include but are not limited to infections by rhinovirus, coronavirus, adenovirus, respiratory syncytial virus, parainfluenza virus, and influenza virus. Individuals who acquire common cold often present with symptoms such as runny nose, coughing, sneezing, sore throat, headache and mild fever.
FLU vaccine only safeguards against the inFLUenza that is by far the most serious cause of common cold. This vaccine is ineffective against the rest of the causes of common cold.
In contrast to the widely held belief, influenza is not the most common cause of cold symptoms. Actually, influenza is the third most common cause of common cold. The top two causes are rhinovirus, the most common, and coronavirus, the second most common cause. As such the best diagnostic bet for a person who is vaccinated against flu and acquires common cold symptoms, is that s/he has contracted either a rhino or a coronavirus infection.