How long is it supposed to it take after getting varicella vaccine to become immune to chicken pox?

4-6 weeks: Hard to be precise because the answer is based on when it was measured and no one checked day after day. At 4-6 weeks, immune response was strong. The exact % response varies by age. A second later dose raises overall response rates a small but significant degree. Two doses seem to keep kids protected for many many years; adults not as exact. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5604a1.htm.