now you are really scaring me, in 1918 the world population were around or less than 2 billion and that flu killed around 40 to 50 million, but yes I hope and pray it will not be millions.
It's unlikely any vaccine will be found in time, and the fatality rate isn't high enough to justify a hail mary trying untested ones. Expectations are for twelve to twenty four months to a vaccine. Some drugs have decent potential mitigating the symptoms and are being tested as I type: if they reduce the number of people with symptoms or the time of effect for these symptoms, it will virtually multiply the number of beds, therefore reducing the total number of deaths. But even then, there are countries whose population will suffer harshly: poor ones with limited healthcare, or those that are unable to get access to enough medicine and equipment (such as Cuba and Iran, thanks to the sanctions, though I suppose China won't give a damn and will send equipment anyway if we don't).
The crux of the matter is that all of this will depend on our resilience and discipline as a society. Resilience, to keep the system working, those who can work at home and still create some wealth should do so, as well as to think about what we can do to help those in need, be they the vulnerable populations who would be endangered by doing their grocery runs or the frontline jobs (medical, delivery, truck drivers, cashiers, police, etc.) who cannot be there for their loved ones, but also discipline to prevent society from breaking down when it'll get harsh to stay inside for weeks at a time.
Kinda relevant:
They are helping us, we should help them.