I really hope I'm not tempting fate but I'm finding the same as Sonya9.
I've had 4 broody reared clutches within the flock this year, all cross bred mutts and none vaccinated.
The oldest are 3 cockerels that are very hale and hearty at 6 months old and will sadly be going in the pot soon but all 3 are serious eye candy at a time when my stalwart cocks are looking very sorry for themselves in moult!.
The second clutch is about 18 weeks old and consists of 5 pullets and 4 cockerels and all looking good so far. I've had a respiratory infection going through the flock and one of these pullets was looking dodgy for a couple of days with that (swollen, bubbly/closed eyes and hunched up and not eating much and sneezing) but she has come through it with no more than a bit of scrambled egg and some natural yoghurt, which suggests her immune system is pretty strong to shrug it off so quickly and easily. The others from that clutch are all fine and I'm hoping to see some eggs from those girls before the end of the year although I'm conscious that will be a risk time for Marek's to strike.
Then I have a clutch of 4 leghorn crosses... there were 5 but one died on day 4 (so I think I can discount Marek's from that). They are 6.5 weeks old and one has persistent pasty butt, which is pretty unusual for broody reared chicks, so I'm a little suspicious there. It's a cockerel though so I'm less concerned. The cockerels that showed classic Marek's symptoms last year, all fully recovered.
The final one is a clutch of 8 that are also 6 weeks and they all appear fine so far.
Apart from going through a heavy moult at the moment and the odd one with slight respiratory symptoms, my original flock are all fine. They all free range together through the day and are locked in a stone stable at night.
Every morning when I let them out and feed them, I brace myself for the sight of one of them limping, but so far I'm delighted to say it hasn't happened. Will be hugely relieved if/when I've had a full year without a Marek's outbreak but maybe that's too optimistic a goal. Happy to count my chickens and my luck on a day by day basis at the moment.
Really feel for those of you who are still losing birds to it and hope your flocks develop some sort of immunity/tolerance to it like mine and Sonya9's seem to be doing.