There is no need to restart the series. Give the second dose of HepB now and be sure there are at least 8 weeks between that dose and the third dose. Increasing the interval between the first two doses has little effect on immunogenicity or final antibody concentration. The third dose confers the maximum level of seroprotection but acts primarily as a booster and appears to provide optimal long-term protection. Longer intervals between the last two doses result in higher final antibody levels but might increase the risk for acquisition of HBV infection among people who have a delayed response to vaccination. No differences in immunogenicity have been observed when one or two doses of hepatitis B vaccine produced by one manufacturer are followed by doses from a different manufacturer.