· just now. Report Abuse. I saw in the comments that someone said the vaccine lasts...as long as you are living, Im sorry but this is simply untrue. I had the combination A & B Vaccine in 2004, got the entire round of 3 shots, returned 6 months after shot 3 and got the hepatitis panel to show if they had taken effect..eport Abuse. Twinrix lasts as long as your living. Medically speaking, it will not matter if you pick up the series with the second injection or if you restart the series. My advice would be to finish with the second dose then get the thrid to finish the series.