Not surprising, back in March there wasn't enough data (there still isn't) to build an accurate model. They were probably working with a range of scenarios and went with one the most pessimistic ones, reasoning that in the aftermath at least they couldn't be accused of lowballing the deaths. Pretty sure we used it in Canada too, our initial estimates were more than 300,000 dead which would mean ~0.8% of the population which would obviously be quite traumatic. Now that it's been going around for 2 months, the trends indicate that the risk of complications sharply drops off in healthy population under age 60 and the vast majority (here in Quebec it's over 97%) of the deaths are occurring in ages 70 and up, with a sharp increase in age 80 and higher vs 70-79. The mortality rate for ages lower than 30 here in Quebec is literally 0%, and you need to keep in mind that this population includes a lot of people who are considered essential, e.g. grocery stores, gas stations, etc. meaning they are very exposed to the virus.
The shotgun approach is overkill, that's becoming clear. You need to isolate seniors and those with pre-existing conditions, put them on full quarantine lockdown, severely limit contact. The rest of us though need to be exposed. There's no vaccine in sight (we still don't have 2003 SARS vaccine), there's no effective treatment, so what's the other option? Stay in lockdown for 12 months hoping that some day everything will be alright? Herd immunity is the only way.
