The Coronavirus Disease 2019 (COVID-19) Immunoglobulin (IgG) Levels Using Chemiluminescence Immunoassay (CLIA) Anti-S-RBD Test in Term Neonates Born to COVID-19 Fully Vaccinated Mothers

Background: Though protective levels of neonatal SARS-CoV2 IgG still warrant further studies, maternal antibodies from COVID-19 vaccination may be the key to neonatal protection against COVID-19 related complications. This study aimed to correlate SARS-CoV2 IgG titers of term newborns delivered to fully vaccinated/boosted mothers with the time of dose completion to delivery and the type of COVID-19 vaccine received by the mothers. Methodology: A single center prospective cohort study that utilized CLIA Anti-S-RBD IgG determination in cord blood was done. Kruskal-Wallis and Mann-Whitney U Test were used to determine significant differences between IgG titers from vaccine types and groups as to trimester when COVID-19 dose was completed. Spearman’s rank was used to determine the correlation between IgG levels and interval of dose completion to delivery. Results: All 177 newborns enrolled in the study had reactive results (> 1 AU/ml) regardless of vaccine type received and trimester of maternal vaccination completion. The highest titers recorded per group was 19,340 AU/ml from the booster group and 5,960 AU/ml from the primary series group. The mRNA vaccinated group exhibited higher titers compared to other vaccine types regardless of the trimester completion for both groups. Conclusions: A significant difference between IgG levels showed that higher titers were noted in the booster group compared to the primary series group across all trimesters. There was also a significant correlation between titer levels and time of dose completion to delivery with higher titers associated with more recent dose completion for both groups.