Haven't the numbers for 18-49 been consistent throughout? I think the issue is how many younger people need sustained medical intervention that is the cause for concern.
We are hearing more and more reports of younger people having severe disease in France, Netherlands, Belgium and the US. I’ve posted several over the past few days. Not good.
The number of cases in the 18-49 age group is misleading. You need to look at the incidence rate of each age group if you want to determine if one age group is more vulnerable than another. If 30% of your population is in that age group, you expect approximately 30% to test positive. You look at differences between expected and actual rate.
Even then the numbers could be misleading. If the younger group isn’t seeking medical care and getting tested, many of the cases will go unreported.