I started taking elderberry at the very beginning of what I thought was an outbreak of shingles. The outbreak stayed small and I opted to stay on the elderberry instead of the doctor prescribed antiviral. Not saying everyone should do that, but it worked for me. It was short lived and very mild.
If that’s the explanation for your attenuated attack then people who take quercetin regularly should experience significantly fewer and/or milder shingles attacks. Is that the case?