If you can get reinfected, would't that mean that a vaccin is impossible? I would like to get some more info on that before I believe it.
Flu vaccines never provide complete immunity against influenza viruses if I am not mistaken. You can still get infected but you'll recover far quicker compared to an unvaccinated person.
Availability of a vaccine has nothing to do with this I believe.
U.S. vaccine effectiveness by start year:[23][24]
2004 10%
2005 21%
2006 52%
2007 37%
2008 41%
2009 56%
2010 60%
2011 47%
2012 49%
2013 52%
2014 19%
2015 48%
2016 40%
2017 36%
2018 47%
https://en.wikipedia.org/wiki/Influenza_vaccineFlu comes in thousands of strains.
Flu vaccines are planned based on projections of what are likely to be the dominant strain(s) that year.
Projections are based on what is happening in the other hemisphere winter and what is circulating at the time.
The better the projections, the more effective, all other things being equal.
Sometimes the projections are good and sometimes they are bad. Even if the vaccine is 100% correctly targeted, it is still far from 100% effective. Vaccines are more about building herd immunity.