oh_sigh is correct, humans are a dead end host for lyme. It's primarily maintained in a mouse reservoir - the larval and nymph ticks feed on infected mice, and then the nymph and adult ticks can expose humans and deer. Deer are not really a big reservoir either, since mostly adult ticks feed on them, but they do move ticks around.

Edit: you can actually try to vaccinate the reservoir, however: https://www.ncbi.nlm.nih.gov/pubmed/24523510

Lyme disease isn't passed from human to human so herd immunity is irrelevant.

My mistake, I thought it was a vaccine for the deer.

As I understand it the vector is mice, not deer. There's a correlation between mouse populations where the juveniles feed and Lyme disease outbreaks 2 years later when the adults latch onto humans.

lyme disease can be passed human to human as a std or the womb from mother to child

Lyme disease is NOT sexually transmitted. https://www.cdc.gov/lyme/faq/index.html

(citation needed)