It doesn't matter where the blog copied data from it's still a weak source. Try linking from the WHO next time.
What I SAID is that I don't know if they're developing any resistance. Of course people are developing antibodies, because the virus is always changing. You don't understand biology very well.
One such change is called “antigenic drift.” These are small changes in the virus that happen continually over time. Antigenic drift produces new virus strains that may not be recognized by the body's immune system. This process works as follows: a person infected with a particular virus strain develops antibody against that virus. As newer virus strains appear, the antibodies against the older strains no longer recognize the “newer” virus, and reinfection can occur. This is one of the main reasons why people can get the flu more than one time. This mutation can cause the virus to die or become even stronger.
In most years, one or two of the three virus strains in the influenza vaccine are updated to keep up with the changes in the circulating flu viruses.
How the Flu Virus Can Change: “Drift” and “Shift” | About (Flu) | CDC