Flu (Influenza) is a viral infection with sudden fever / chills, headache, body pain, muscle and joints pain, tiredness, vomiting sensation and cough.
It is not the same as the regular cough and cold (common cold) but it is similar and more severe.
Transmitted by coughing and sneezing. Shopping malls / large gatherings contribute to the spread.
Severe illness with complications can occur in children < 5 years, adults > 65 years, pregnancy, people with diabetes, heart, lung, kidney problems.
On recovery, severe tiredness could persist for a few weeks.
Vaccines available are 1) Injection 2) Nasal spray