CD40LG and infection: We found that 29 participants (4.8 %) had indeterminate results (HBsAg-, anti-HBc+, anti-HBc-IgM-, anti-HBs-) with isolated anti-HBc positivity caused by long-standing resolved infections with low anti-HBs titers or current infections with low HBsAg titers (Table 1 and Fig. 1).