Is the vaccine effective in preventing all cases of chickenpox?
No vaccine is 100% effective in preventing disease. For chickenpox vaccine, about 9 out of every 10 people who are vaccinated with two doses are completely protected from chickenpox. In addition, the recommended two-dose regimen is virtually 100% effective in preventing severe disease. If a vaccinated person does get chickenpox, it is usually a very mild case lasting only a few days and involving fewer skin lesions (usually less than 50, which may resemble bug bites more than typical, fluid-filled chickenpox blisters), mild or no fever, and a quicker recovery.
