I have taken lysine when I had shingles, and gave it to my child who had chicken pox.
My experience after a recurrence with shingles was I needed to keep taking it a few weeks, and not stop as soon as my symptoms subsided.
IIRC, I took 1200 mg a day.
If anyone is interested I found it here:
https://www.pipingrock.com/l-lysine?keywords=lysine&qid=1631296910
They seem to have great prices.