True vaccines such as the ones you mentioned use complete DNA from the virus in question. The Covid vaccine is only an RNA vaccine, which is only half the complete cell. It might work on the original but the RNA breaks down and quits working. DNA stays intact and your body develops antibodies to fight it.
Flu virus mutates every year, usually in China. The last flu in the spring in Asia is used for the flu vaccine in the fall in America. It usually takes about 6 months to get here.
China raises chickens above hogs. Their crap gets in the hog feed. Chicken manure is only half digested food, so the hogs eat it and what the chickens scatter. Anyway, the chickens can get bird flu, then transmit to hogs, which in turn transmit it to humans, and back and forth it goes. The WHO has asked China to change their agricultural methods to raise chickens and hogs separately, but they won't. So you need a new flu shot every year.
I got the flu, pneumonia, or bronchitis several years in a row back in the early 90's. I started taking the flu shot and haven't had any of the diseases since then.
Covid shots were and still are experiments, not full vaccines. Just get some hydroxy and zinc, or ivermectin and deal with it. They are used overseas all the time now. They work. Find a doctor that will prescribe it. The problem with covid is that it mutates faster than the flu, so there is no time to make a vaccine. The flu mutates about once a year and they have time to make the vaccine for the next round coming out of Asia. Covid, no time.