Maternal antibody titers against the RSV N protein
The mean (SD) value of maternal antibody titers against the RSV N protein among newborns was 502 (255) RU/mL. There was no significant difference in mean values according to sex (Figure 2A), type of pregnancy (Figure 2B), or mode of delivery (Figure 2C). The mean value was significantly different according to the term of pregnancy (p < 0.001; Figure 2D); it was significantly lower in preterm newborns (i.e. extremely, very, and moderate-to-late combined) than in those born at term (377 RU/mL vs. 516 RU/mL, p < 0.001), in newborns with a low birth weight than in those with a birth weight ≥ 2500g (401 RU/mL vs. 515 RU/mL, p < 0.001; Figure 2E), in newborns from primiparous mother than those from multiparous mothers (470 RU/mL vs. 522 RU/mL, p < 0.05; Figure 2F) and in newborns whose birth occurred before the peak of the epidemic than in those born after (458 RU/mL vs. 542 RU/mL, p < 0.001; Figure 2G). There was no significant difference in mean antibody titers between infants who experienced a VS-LTRI (irrespective of RSV detection) and those who did not (466 RU/mL vs. 505 RU/mL, p = 0.37; Figure 2H).