Every year from September to October, before the peak season for influenza, it is very necessary to arrange for the elderly and frail family members to get a flu shot to effectively prevent the flu. But why does one shot only last for a year? There are two reasons.

The influenza virus is very cunning and changeable, especially the influenza A virus, which constantly changes its surface protein structure, like changing a set of different colored or styled clothes every year. This is medically referred to as "antigen drift," which makes the antibodies produced in our bodies through vaccination or naturally to fight the influenza virus unable to recognize it, making severe infections very easy to occur. The 2009 H1N1 influenza pandemic is a typical example.

Second, the antibodies generated by the flu vaccine can last for about 6-8 months. By the time the flu season comes around the next year, their immunity is basically gone. Therefore, for elderly and frail individuals, such as those over 70, infants and young children, pregnant women, and especially those with chronic heart and lung diseases, diabetes, or other weakened immune systems, it is recommended to get a flu vaccine every year.

Did you remember all that?