I looked through the transcript and I don't see anything that fits.
Kor
It certainly would fit the show better, and it's how I squint to make the show better for me, but it's not actually stated in the show.
Oops! I ment 300 years earlier, not 30 years earlier.
I'm sorry that I accidentially misled you into thinking there was evidence which supports a shorter time span since the diaster.
So here is a theory in compensation for that.
Maybe there tthere could have been two time spans which the protagonists thought were only one time span, but the difference was discovered later after the episode was over..
Maybe the community was abaodoned and became a ghost town about 300 years earlier due to unmentioned factors. Many communities on Earth have been abandoned for various reasons.
And centuries later a research project moved into that abandoned community for reasons of secrecy. So naturally they didn't fix up the mess, but left it the way it was, s noobdy would notice it was occupied. Possibly they knew that the community had vast abandoned undgeround facilites,and used them to live and work in, with the above ground lab being just a headquarters..
Thus the kids could have been only decades instead of centuries old. Perhaps the virus diaster had struck just a few years ago, when even the youngest kids seen wouldhave been babies or toddlers. Maybe the virius never stopped aging at all and was a total failure.
Possibly there were hundreds of millions or even billions of orphaned kids on the planet to be taken care of.