Does maternal SARS-CoV-2 infection or SARS-CoV-2 vaccination trigger an inflammatory response in the fetus?

SARS-CoV-2 infection triggers a significant maternal inflammatory response. There is a dearth of data regarding whether maternal SARS-CoV-2 infection or SARS-CoV-2 vaccination triggers an inflammatory response in the fetus. Fetal Inflammatory Response Syndrome (FIRS) has been described in other clinical conditions such as intraamniotic infection and has been defined as a cord blood Interleukin-6 (IL-6) level > 11 pg/ml. The objective of the study is to evaluate Il-6 levels in the cord blood of three delivering women: SARS-CoV-2 infection group, SARS-CoV-2 vaccinated group, and a control group. A prospective case control study of a total of 61 pregnant women who presented for delivery at William Beaumont Hospital, Royal Oak, MI. All patients were tested for SARS-CoV-2 infection by polymerase chain reaction test (PCR). Three groups were evaluated: 22 pregnant women with positive SARS-CoV-2 PCR test (case group), 23 Pregnant women with negative SARS-CoV-2 PCR test (control group), and 16 pregnant women who had recent SAR-CoV-2 vaccination and a negative SARS-CoV-2 PCR test. At delivery, cord blood was collected for IL-6 levels. IL-6 level (mean +/- SEM) was for the case group: 8.99 +/- 3.33 pg/ml, control group: 5.19 +/- 0.76 pg/ml, and vaccine group: 7.11 +/- 2.47 pg/ml. There was no statistical difference between the three groups with ANOVA p-value 0.51. Pairwise comparison also revealed no statistical difference with p-values for case versus control, case versus vaccine, and control versus vaccine being 0.52, 0.85, and 0.84 respectively. IL-6, the most sensitive measure of inflammation in obstetric practice, did not identify increased inflammation in PCR negative newborns of vaccinated or SARS-CoV-2 infected mothers. Evaluation using other markers of possible intrauterine inflammation is warranted.