There are basically two paths: act swiftly and decisively at the very beginning. Immediately close your borders. Find the infected and contact trace them. Dragnet test where necessary. Haul off the sick to quarantine locations run by the government. etc. Then you don't need to lock down the entire country.

Path 2 is you fuck it up and Covid-19 is running rampant through your entire population. Of course at this point closing borders and contact tracing is 100% pointless. It's in this environment where lockdown is the only way you can accomplish anything.