CD27 and hepatitis A virus infection: In summary, we report significantly higher frequencies of CD24highCD38high Breg in parallel with significantly lower IL-10 expression levels of CD24+CD27+ and CD24highCD38high Breg in 2nd HBvac NR compared to 2nd HBvac R. Anti-HBs seroconversion accompanied by a decrease of Breg numbers after booster immunization with a third-generation hepatitis B vaccine could indicate a positive effect of third-generation hepatitis B vaccines on Breg-mediated immunomodulation in hepatitis B vaccine non-responders.