Once they've had it, the vaccine isn't going to do anything. The vaccine is usually given at 12 - 16 weeks of age and it should be given only to healthy birds. When they recover from the illness they should have some immunity to it and usually won't get it again. Fowl pox doesn't affect the eggs either way. https://edis.ifas.ufl.edu/publication/VM021
Basically just supportive care. If it's just the dry form, it usually lasts a few weeks and clears up with no real issues. If there are any lesions near the eyes, keep an eye on those, it can sometimes cause a secondary eye infection which you can use terramycin eye ointment (no prescription required usually) or plain neosporin a couple of times a day in the affected eye if needed. It doesn't happen a lot, but can, just want you to be aware. If they were to develop the wet form, which means lesions in the mouth and throat, then more supportive care might be needed as they may not want to eat or drink well. In those types of cases you might need to hand feed or tube feed to help get them through it. The dry form is far more common than the wet form.
The vaccine won't help your sick birds, but I would consider vaccinating any future birds you add since you now know the disease is an issue in your area