>Will the flu gradually vanish with spring/summer? Any medical expert can explain me please?
Likely. One important route of infection is, that you touch something like a doorknob with viruses on them, and smear them in your nose. Viruses die faster on such surfaces when it's warm. This reduces infections. Also, people spend less time indoors with other people when it's warm outside, and it's inside, where the pathogens are.
However, when it's summer in china, it's winter in africa and australia.
>It's a virus, not a bacteria, so it can be vaccinated against, in principle.
You can vaccinate against bacteria.
Also, ebola-chan was wiped out because she mutated into a more infectious but asymptomatic strain, which vaccinated people against the strain that kills you. This was stupid luck, and had nothing to do with human intervention.
Also, there are other corona-ciruses like SARS and MERS, against which there's still no vaccine, even though they're pretty lethal. I wouldn't expect a vaccine anytime soon. The pharma companies say, that they have hundreds of somethings, but all of them very likely won't work, if you don't assume, that the world fundamentally changed in the last 10 years.