Frequency of vaccine-elicited IgG1 (A), IgG2 (B), IgG3 (C), and IgG4 (D) was determined in both maternal and cord blood plasma. The majority of mothers and infants had detectable levels of IgG1 against the vaccines tested. A high proportion of mothers and infants also had vaccine-specific IgG4 antibodies whereas the frequency of vaccine-elicited IgG2 and IgG3 responses was generally lower. * P < 0.05, ** P < 0.01, *** P < 0.001, Chi-Square Test of Independence.