[Impact of asymptomatic maternal SARS-CoV-2 infection on foetal growth]. / Impacto de la infección materna asintomática por SARS-CoV-2 sobre el crecimiento fetal.

Introduction: The impact of asymptomatic infection by SARs-CoV-2 on foetal growth has not been described. The purpose of our study is to determine whether there is an increased risk of foetal growth restriction in pregnancies in which asymptomatic or mild infection by SARS-CoV-2 has been detected. Material and methods: Retrospective case-control study with a subset of pregnant women with a small for gestational age foetus. Groups were established according to birth weight percentile. Previous SARS-CoV-2 infection was defined by positive antibodies obtained on admission to hospital for delivery. Results: No statistically significant differences between controls and cases were recorded in terms of positive IgG antibodies (11.5 vs. 8.8%). There were no premature births or significant differences in the date or type of delivery. Conclusions: Asymptomatic infection by SARs-CoV-2 during pregnancy does not seem to affect foetal growth.

Humoral and cellular responses to SARS-CoV-2 vaccination in patients with multiple sclerosis and other autoimmune diseases

Background: Information about humoral and cellular responses to SARS-CoV-2 vaccination in patients with Multiple Sclerosis (PwMS) and other autoimmune diseases (AID) is scarce. Objective: To determine humoral and cellular responses after SARS-CoV-2 vaccination in PwMS and anti-CD20-treated patients with other AID. Methods: Ongoing prospective study performed in two Catalan MS centres from February 2021. Unvaccinated adult pwMS and other anti-CD20-treated AID were recruited. Demographic, clinical and laboratory data were obtained. Whole blood samples were obtained before and 30-90 days after vaccination. The humoral response to SARS-CoV-2 was qualitatively and quantitatively measured before and after vaccination with commercial chemiluminescence immunoassays targeting SARS-CoV-2 antibodies against spike (TrimericS, IgG anti-S) and nucleocasid proteins (Elecsys, Ig anti-N). In 150 selected patients according to diseasemodifying therapy (DMT), the SARS-CoV-2 specific T-cell response was assessed after vaccination by a whole blood Interferon-Gamma Release immuno Assay (IGRA) that uses two Qiagen proprietary mixes of SARS-CoV-2 S protein (Ag.1 and Ag.2) selected to activate both CD4 and CD8 T cells. Results: 457 patients have been enrolled in the study (anti-CD20 therapy n=164, S1P DMTs n=37, natalizumab n=32, cladribine n=29, alemtuzumab n=31, other DMTs n=129, no DMT n=35). Participants characteristics are: mean age 48.1 years (SD 12.0), 69% female, 422 pwMS (29.4% progressive forms) and 35 with other AID, disease duration 13.9 years (IQR 14.1), median EDSS 3.0 (IQR 3.0). 450 have been fully vaccinated (94.2% mRNA vaccine). Pre-vaccination samples were collected 0.33 days (SD 0.5) before the first vaccine dose of which 12 (3.35%) had positive anti S/N immunoglobulin (Ig). As of June 30th, 42 post-vaccination samples have been obtained (1.3 months [SD 0.42] after the 2nd vaccination dose). Positive IgG rates were 44.8% (n=13/29) for CD20s, 100% (8/8) for other DMTs and 100% (4/4) for no DMT. No anti-N Ig were detected. Media titres of anti-S IgG were lower in anti-CD20-treated patients (7.8 [IQR 50.1]) compared to untreated patients (800 [0], p<0.01) or other DMTs (755 [228], p<0.01). Conclusions: Initial results of the study suggest blunted anti-S/N Ig response under anti-CD20 therapy. Knowledge of the cellular response in these patients will be crucial. Data from the cellular study and the completed humoral study will be presented at the meeting.