The vaccine demonstrated a reduction in the rate of infections, but fell short of a key statistical requirement.

Lyme disease is an illness caused by bacteria most commonly spread to humans from ticks. It can cause arthritis, muscle weakness and pain.

The vaccine demonstrated a reduction in the rate of infections, but fell short of a key statistical requirement.

The first human Lyme disease vaccine was 73% effective against the tick-borne illness, says Pfizer. They still plan to seek approval.