We can roughly estimate how long that will take if we stay at R=1. That's maybe 100k new infections monthly in germany. Meaning it takes ~40 years to reach 60%. (83000k*0.6/100k/12)
Maybe it's less if you can get more aggressive with more immunity, but even if I'm wrong by a factor of 10 it's still years and the vaccine is the more realistic bet.
Maybe it's less if you can get more aggressive with more immunity, but even if I'm wrong by a factor of 10 it's still years and the vaccine is the more realistic bet.