My wife developed shingles a few years ago, but luckily she managed to see the GP within a day or so of it starting, and the swift administration of the antiviral medication got it under control. It started retreating up her arms within the first week, but it was another 5 weeks or so before it was no longer a problem.
Apparently the medication is only effective if administered within the first week.
The vaccine has been available to the over 70s for some time, but, because of the small stocks, it is restricted to certain age ranges, and they change every year. I understand that the causative virus is related to the chickenpox virus and once you've been infected you have it lying dormant for life, and can erupt at any time. Since she'd had chickenpox as a child, she was keen to get the shingles vaccine, but whenever she was about to reach the correct range they changed it.