With a lockdown you slow down the infection. This has a few goals at the same time. First, you lessen the load of the healthcare system. If a lot of people get

With a lockdown you slow down the infection. This has a few goals at the same time. First, you lessen the load of the healthcare system. If a lot of people get sick at the same time, hospitals would be swamped and more people would die because care is impossible. Second, you can bring the disease from an exponential growth to sub-exponential, potentially containing it mostly (this is what happened for example in Germany, where tracking individual infections is now possible again). Third, you buy yourself time until a vaccine is available. Even if no vaccine is going to appear in the near future, as long as you slow it down long enough (1-2 years) from reaching saturation in the population, that's lives saved.