I successfully treated a persistent hand / feet / knee warts infection with 3 shots of Gardasil-9. The common warts are supposed to clear on their own within 2 years, but it was not the case for me. They all cleared out about a 1 year after the first shot, never to return. Including a deep plantar one that was completely immune to cryotherapy
I could not get rid of warts for 3 years. The plantar ones were unkillable by cryotherapy and small warts that were spread throughout hands would come back. I took HPV 9-valent vaccine, I am not sure whether it helped or not but it could have increased immune response to the family of viruses. About 6 months after the last dose, I started eating garlic every day and increased dose of vitamin D-3 and C (6,000 iu and 1500mg to be exact) which I have already been taking daily. I have noticed that 5 days in, a hard to treat wart on my thumb started getting smaller. A few weeks later there was no signs of multiple plantar warts. Ever since I am just not getting warts. Sometimes when I miss a lot of sleep one will pop up on my hand for a few days and disappear. It's an immune system issue. It was not placebo either, I have increased vitamins doses / started eating garlic for completely different reasons and was surprised to see the wart disappear all out of the sudden.
Also there were multiple studies where the efficency of inter-lesion administration of the vaccine had quite high success rate. This is a recent one I could find now: https://onlinelibrary.wiley.com/doi/full/10.1111/1346-8138.1... I'm guessing this is not going to get very popular though, cryotherapy is like SaaS, the vaccine is buy once. The doctor I visited earned good money to run his freezing device which accounted for a 10 minute visit. It's a shame because while having persistent warts is not the end of the world, it's a really pesky problem to have and there are solutions to it, but they are not easily available.
https://www.sciencedirect.com/science/article/pii/S277270762...