Vertical transmission of SARS-CoV2 during pregnancy: A high-risk cohort

Prenatal SARS-CoV-2 infection results in neurodevelopmental and behavioral outcomes in mice

Prenatal exposure to viral pathogens has been known to cause the development of neuropsychiatric disorders in adulthood. Furthermore, COVID-19 has been associated with a variety of neurological manifestations, raising the question of whether in utero SARS-CoV-2 exposure can affect neurodevelopment, resulting in long-lasting behavioral and cognitive deficits. Using a human ACE2-knock-in mouse model, we have previously shown that prenatal exposure to SARS-CoV-2 at later stages of development leads to fetal brain infection and gliosis in the hippocampus and cortex. In this study, we aimed to determine whether infection of the fetal brain results in long-term neuroanatomical alterations of the cortex and hippocampus or in any cognitive deficits in adulthood. Here, we show that infected mice developed slower and weighed less in adulthood. We also found altered hippocampal and amygdala volume and aberrant newborn neuron morphology in the hippocampus of adult mice infected in utero. Furthermore, we observed sex-dependent alterations in anxiety-like behavior and locomotion, as well as hippocampal-dependent spatial memory. Taken together, our study reveals long-lasting neurological and cognitive changes as a result of prenatal SARS-CoV-2 infection, identifying a window for early intervention and highlighting the importance of immunization and antiviral intervention in pregnant women.

Association between the degree of severity of COVID-19 infection during pregnancy and preterm premature rupture of membranes in a level III hospital in Peru

OBJECTIVES.

To determine the association between the degree of severity of COVID-19 infection during pregnancy and preterm premature rupture of membranes (PPROM) in a level III hospital in Peru.

MATERIALS AND METHODS.

Cross-sectional, analytical and observational study in women older than 18 years diagnosed with COVID-19 infection during pregnancy, between the years 2020 and 2022. Clinical and obstetric variables were collected. The chi-square and Fisher's exact tests were used for the descriptive analysis. For the multivariate analysis, we calculated the prevalence ratio by using Poisson regression in crude and adjusted models. All statistical tests were performed considering a value of p<0.05 as significant and with a confidence level of 95%.

RESULTS.

We analyzed data from 163 pregnant women with COVID-19, of which 9.2% had PPROM; all were symptomatic cases. Mild COVID-19 cases were 1.10 times more likely to have PPROM (RPa=1.10; 95%CI: 1.02-1.18) and moderate/severe cases were 1.64 times more likely (RPa=1.64; 95%CI: 1.43-1.87), compared to asymptomatic cases.

CONCLUSIONS.

We identified that a higher degree of severity of COVID-19 infection during pregnancy was associated with a higher probability of having PPROM.

SARS-CoV-2-Placental effects and association with stillbirth

SARS-CoV-2 has had a significant impact on pregnancy outcomes due to the effects of the virus and the altered healthcare environment. Stillbirth has been relatively hidden during the COVID-19 pandemic, but a clear link between SARS-CoV-2 and poor fetal outcome emerged in the Alpha and Delta waves. A small minority of women/birthing people who contracted COVID-19 developed SARS-CoV-2 placentitis. In many reported cases this was linked to intrauterine fetal death, although there are cases of delivery just before imminent fetal demise and we shall discuss how some cases are sub-clinical. What is surprising, is that SARS-CoV-2 placentitis is often not associated with severe maternal COVID-19 infection and this makes it difficult to predict. The worst outcomes seem to be with diffuse placental disease which occurs within 21 days of COVID-19 diagnosis. Poor outcomes are often pre-dated by reduced fetal movements but are not associated with ultrasound changes. In some cases, there has also been maternal thrombocytopenia, or coagulation abnormalities, which may provide a clue as to which pregnancies are at risk of fetal demise if a further variant of concern is to emerge. In future, multidisciplinary collaboration and cross-boundary working must be prioritised, to identify quickly such a phenomenon and provide clinicians with clear guidance for reducing fetal death and associated poor outcomes. While we wait to see if COVID-19 brings a future variant of concern, we must focus on appropriate future management of women who have had SARS-CoV-2 placentitis. As a placental condition with an infectious aetiology, SARS-CoV-placentitis is unlikely to recur in a subsequent pregnancy and thus a measured approach to subsequent pregnancy management is needed.

Data-driven, cross-disciplinary collaboration: lessons learned at the largest academic health center in Latin America during the COVID-19 pandemic

Introduction

The COVID-19 pandemic has prompted global research efforts to reduce infection impact, highlighting the potential of cross-disciplinary collaboration to enhance research quality and efficiency.

Methods

At the FMUSP-HC academic health system, we implemented innovative flow management routines for collecting, organizing and analyzing demographic data, COVID-related data and biological materials from over 4,500 patients with confirmed SARS-CoV-2 infection hospitalized from 2020 to 2022. This strategy was mainly planned in three areas: organizing a database with data from the hospitalizations; setting-up a multidisciplinary taskforce to conduct follow-up assessments after discharge; and organizing a biobank. Additionally, a COVID-19 curated collection was created within the institutional digital library of academic papers to map the research output.

Results

Over the course of the experience, the possible benefits and challenges of this type of research support approach were identified and discussed, leading to a set of recommended strategies to enhance collaboration within the research institution. Demographic and clinical data from COVID-19 hospitalizations were compiled in a database including adults and a minority of children and adolescents with laboratory confirmed COVID-19, covering 2020-2022, with approximately 350 fields per patient. To date, this database has been used in 16 published studies. Additionally, we assessed 700 adults 6 to 11 months after hospitalization through comprehensive, multidisciplinary in-person evaluations; this database, comprising around 2000 fields per subject, was used in 15 publications. Furthermore, thousands of blood samples collected during the acute phase and follow-up assessments remain stored for future investigations. To date, more than 3,700 aliquots have been used in ongoing research investigating various aspects of COVID-19. Lastly, the mapping of the overall research output revealed that between 2020 and 2022 our academic system produced 1,394 scientific articles on COVID-19.

Discussion

Research is a crucial component of an effective epidemic response, and the preparation process should include a well-defined plan for organizing and sharing resources. The initiatives described in the present paper were successful in our aim to foster large-scale research in our institution. Although a single model may not be appropriate for all contexts, cross-disciplinary collaboration and open data sharing should make health research systems more efficient to generate the best evidence.

Umbilical cord clamping in the early phases of the COVID-19 era - a systematic review and meta-analysis of reported practice and recommendations in guidelines

OBJECTIVES

At the beginning of the COVID-19 pandemic, delayed umbilical cord clamping (CC) at birth may have been commonly discouraged despite a lack of convincing evidence of mother-to-neonate SARS-CoV-2 transmission. We aimed to systematically review guidelines, and reports of practice and to analyze associations between timing of CC and mother-to-neonate SARS-CoV-2 transmission during the early phases of the pandemic.

METHODS

Major databases were searched from December 1, 2019, to July 20, 2021.

INCLUSION

studies and guidelines describing CC practice in women with SARS-CoV-2 infection during pregnancy until 2 postnatal days, giving birth to live-born neonates.

EXCLUSION

no extractable data. Two reviewers independently screened studies for eligibility and assessed study quality. Pooled prevalence rates were calculated.

RESULTS

Forty-eight studies (1476 neonates) and 40 guidelines were included. Delayed CC was recommended in 70.0% of the guidelines. Nevertheless, delayed CC was reported less often than early CC: 262/1476 (17.8%) vs 511/1476 (34.6%). Neonatal SARS-CoV-2 positivity rates were similar following delayed (1.2%) and early CC (1.3%). Most SARS-CoV-2 transmissions (93.3%) occurred in utero.

CONCLUSION

Delayed CC did not seem to increase mother-to-neonate SARS-CoV-2 transmission. Due to its benefits, it should be encouraged even in births where the mother has a SARS-CoV-2 infection.

SYSTEMATIC REVIEW REGISTRATION

Prospero CRD42020199500.

Impact of COVID-19 on Fetal Outcomes in Pregnant Women: A Systematic Review and Meta-Analysis

Background: Coronavirus disease (COVID-19) is a pandemic causing respiratory symptoms, taste alterations, olfactory disturbances, and cutaneous, cardiovascular, and neurological manifestations. Recently, research interest has shifted to reproductive health to understand the factors predisposing to COVID-19 infection in pregnancy, the consequences of the infection on the fetus and on the mother, and possible vertical transmission through the placenta. Pregnancy does not increase the risk of SARS-CoV-2 infection, according to studies. However, contrary to non-pregnant women, pregnancy worsens the clinical outcome of COVID-19. Studies investigating the effects of COVID-19 on pregnancy women are heterogeneous, and the results are often conflicting. Objectives: The goal of the current work was to offer a thorough and up-to-date systematic review of, and meta-analysis on, the impact of COVID-19 on ovarian function, pregnancy, and fetal outcomes. Search strategy: This meta-analysis (PROSPERO n. CRD42023456904) was conducted using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) protocols. The search for relevant material was conducted using PubMed, Scopus, Cochrane, and Embase databases, through to 15 December 2022. Selection criteria: Original articles on fertile pregnant women or women attempting to become pregnant, with an active case of, or history of, SARS-CoV-2 infection were included, and reproductive function was compared to that of uninfected women. Data collection and analysis: The effects of COVID-19 on female reproductive function, particularly ovarian function, the profile of female sex hormones, pregnancy outcomes and fetal outcomes were the focus of our search. Quantitative analysis was performed with Comprehensive Meta-Analysis Software. The standard difference of the mean was calculated for the statistical comparison between cases and controls. Cochran's Q test and heterogeneity (I2) indexes were used to assess statistical heterogeneity. Sensitivity analysis and publication bias tests were also performed. Main Results: Twenty-eight articles met our inclusion criteria, for a total of 27,383 patients pregnant or looking to have offspring, with active or anamnestic COVID-19, and 1,583,772 uninfected control women. Our study revealed that there was no significant difference between COVID-19 patients and the control group in terms of maternal characteristics such as age, body mass index (BMI) and comorbidities that could affect pregnancy and fetal outcomes. The risk of a miscarriage or Cesarean delivery was significantly lower, while the risk of fetal death or premature delivery was significantly higher in COVID-19 patients than in the controls. None of the included studies evaluated hormonal profiles or investigated the presence of infertility. Conclusions: Maternal comorbidities, age, and BMI do not raise the risk of COVID-19. However, pregnant women with COVID-19 had a lower risk of miscarriage and Cesarean delivery, possibly because of better prenatal care and high levels of observation during labor. COVID-19 during pregnancy increases the risk of fetal death and premature delivery.

SARS-CoV-2 placentitis, stillbirth, and maternal COVID-19 vaccination: clinical-pathologic correlations

Stillbirth is a recognized complication of COVID-19 in pregnant women that has recently been demonstrated to be caused by SARS-CoV-2 infection of the placenta. Multiple global studies have found that the placental pathology present in cases of stillbirth consists of a combination of concurrent destructive findings that include increased fibrin deposition that typically reaches the level of massive perivillous fibrin deposition, chronic histiocytic intervillositis, and trophoblast necrosis. These 3 pathologic lesions, collectively termed SARS-CoV-2 placentitis, can cause severe and diffuse placental parenchymal destruction that can affect >75% of the placenta, effectively rendering it incapable of performing its function of oxygenating the fetus and leading to stillbirth and neonatal death via malperfusion and placental insufficiency. Placental infection and destruction can occur in the absence of demonstrable fetal infection. Development of SARS-CoV-2 placentitis is a complex process that may have both an infectious and immunologic basis. An important observation is that in all reported cases of SARS-CoV-2 placentitis causing stillbirth and neonatal death, the mothers were unvaccinated. SARS-CoV-2 placentitis is likely the result of an episode of SARS-CoV-2 viremia at some time during the pregnancy. This article discusses clinical and pathologic aspects of the relationship between maternal COVID-19 vaccination, SARS-CoV-2 placentitis, and perinatal death.

Outcome of Newborns with Confirmed or Possible SARS-CoV-2 Vertical Infection-A Scoping Review

Severe acute respiratory syndrome virus 2 (SARS-CoV-2), the virus that causes 2019 coronavirus disease (COVID-19), has been isolated from various tissues and body fluids, including the placenta, amniotic fluid, and umbilical cord of newborns. In the last few years, much scientific effort has been directed toward studying SARS-CoV-2, focusing on the different features of the virus, such as its structure and mechanisms of action. Moreover, much focus has been on developing accurate diagnostic tools and various drugs or vaccines to treat COVID-19. However, the available evidence is still scarce and consistent criteria should be used for diagnosing vertical transmission. Applying the PRISMA ScR guidelines, we conducted a scoping review with the primary objective of identifying the types, and examining the range, of available evidence of vertical transmission of SARS-CoV-2 from mother to newborn. We also aimed to clarify the key concepts and criteria for diagnosis of SARS-CoV-2 vertical infection in neonates and summarize the existing evidence and advance the awareness of SARS-CoV-2 vertical infection in pregnancy. Most studies we identified were case reports or case series (about 30% of poor quality and inconsistent reporting of the findings). Summarizing the existing classification criteria, we propose an algorithm for consistent diagnosis. Registration: INPLASY2022120093.

Monitoring SARS-CoV-2 seroprevalence over time among pregnant women admitted to delivery units: Suitability for surveillance

OBJECTIVES

To determine SARS-CoV-2 seroprevalence over time and risk factors among pregnant women at delivery in São Paulo, Brazil; and to evaluate the suitability of pregnant women as a sentinel population for SARS-CoV-2 serosurveillance.

METHODS

Unselected consecutive pregnant women presenting at the labor ward of a single large hospital between July 20th 2020 to February 21st 2021 were enrolled and tested for SARS-CoV-2 serology using two assays: the rapid chromatic Wondfo One Step (for total IgA and IgG detection) and Roche Elecsys assay (detecting anti-nucleoprotein [N] IgG). SARS-CoV-2 seroprevalence was computed as smooth spline function over time with 95% confidence intervals (CI). Risk factors were evaluated for positivity by each assay. We compared timepoint seroprevalence by the two assays with four concomitant community household surveys (HHS), in which the Roche assay was used, to determine the sensitivity and relevance of the pregnant women population as sentinel population.

RESULTS

Overall SARS-CoV-2 seroprevalence was 28.9% (221/763) by Roche and 17.9% (137/763) by Wondfo. Reported symptoms experienced during pregnancy were all significantly correlated with being SARS-CoV-2 seropositive at delivery with any assay (with odds-ratios ranging from 3.0 [95% CI: 2.1-4.3] for coryza to 22.8 [95% CI: 12.3-46.6] for ageusia). Seropositivity by either assay was high in women at delivery in the early period of the pandemic (June 2020), compared with seropositivity in women from the concomitant HHS: 44.1% (95% CI: 21.8-66.4) for Roche, 54.1% (30.9-78.5) for Wondfo, versus 11.4% (95% CI: 9.2-13.6) for HHS. For later periods (October 2020 and January 2021), the seropositivity in women at delivery measured by Roche corresponded well with the prevalence found among women in the HHS using the same assay, whilst prevalence measured by Wondfo dropped.

CONCLUSIONS

Women at delivery represent a highly exposed and readily accessible population for sentinel surveillance of emerging infections such as SARS-CoV-2.

Post-Viral Fatigue Following SARS-CoV-2 Infection during Pregnancy: A Longitudinal Comparative Study

Studies reported post-COVID-19 fatigue in the general population, but not among pregnant women. Our objectives were to determine prevalence, duration, and risk factors of post-viral fatigue among pregnant women with SARS-CoV-2. This study involved 588 pregnant women with SARS-CoV-2 during pregnancy or delivery in Brazil. Three groups were investigated: G1 (n = 259, symptomatic infection during pregnancy); G2 (n = 131, positive serology at delivery); G3 (n = 198, negative serology at delivery). We applied questionnaires investigating fatigue at determined timepoints after infection for G1, and after delivery for all groups; fatigue prevalence was then determined. Cox regression was used to estimate hazard ratio (HR) and 95% CI of the risk of remaining with fatigue in G1. Overall fatigue prevalence in G1 at six weeks, three months and six months were 40.6%, 33.6%, and 27.8%, respectively. Cumulative risk of remaining with fatigue increased over time, with HR of 1.69 (95% CI: 0.89-3.20) and 2.43 (95% CI: 1.49-3.95) for women with moderate and severe symptoms, respectively. Multivariate analysis showed cough and myalgia as independent risk factors in G1. Fatigue prevalence was significantly higher in G1 compared to G2 and G3. Post-viral fatigue prevalence is higher in women infected during pregnancy; fatigue's risk and duration increased with the severity of infection.

Clinical, Laboratory, and Imaging Findings of Pregnant Women with Possible Vertical Transmission of SARS-CoV-2-Case Series

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic significantly impacted the general population's health. At times, the infection has unfavorably influenced pregnancy evolution and the result of birth. However, vertical transmission of the virus is rare and generates controversial discussions. The study aimed to highlight the clinical, laboratory, and imaging findings of pregnant women with confirmed Coronavirus Disease 2019 (COVID-19) with possible vertical transmission and identify possible factors that encourage vertical transmission. Between 1 April 2020 and 31 December 2021, 281 pregnant women diagnosed with COVID-19 gave birth in the Obstetrics and Gynecology Departments of the tertiary unit of County Emergency Clinical Hospital from Timisoara. Three newborns (1.06%) tested positive. The characteristic of these three cases was described as a short series. In two cases, the patients were asymptomatic. In one case, the patient developed a mild form of COVID-19 with a favorable evolution in all cases. We did not identify the presence of smoking history, vaccine before admission, atypical presentation, fever, or chest X-ray abnormalities. We note possible factors that encourage vertical transmission: Pregnancy-induced hypertension, thrombophilia, asymptomatic cough, an asymptomatic or mild form of the disease, a ruptured membrane, and cesarean. The laboratory results highlight the inconstant presence of some changes found in the list of potential predictors of the severity of the infection: Lymphopenia, high values of C-reactive protein, D-dimer, fibrinogen, platelets, Aspartate Aminotransferase, Lactate dehydrogenase, and ferritin. The study's conclusion of this small group suggests that there may have been an intrauterine infection in late pregnancy and described characteristics of the pregnant women. Possible risk factors that could encourage vertical transmission have been identified.

Outcome of Neonates Born to SARS-CoV-2-Infected Mothers: Tertiary Care Experience at US–Mexico Border

Background: SARS-CoV-2 has affected millions of people around the world. There is a need for data on the effects of this infection on neonates admitted to neonatal intensive care (NICU) units born to infected mothers. Here, we decided to analyze neonates born to mothers who tested positive for SARS-CoV-2 and admitted to NICU compared with neonates who remained with their mothers. Methods: All pregnant mothers who tested positive for SARS-CoV-2 during pregnancy between 1 June 2020 and 30 June 2021, along with all neonates born to infected pregnant women, were included in this study. We then compared the neonates admitted to NICU with the neonates who remained with their mothers. Results: Eighty-eight neonates were born to eighty-eight SARS-CoV-2-positive mothers. Fifteen of these neonates were admitted to the NICU. The mothers of the neonates admitted to the NICU were more likely to have received prenatal care outside of the USA. In addition, the neonates admitted to the NICU were more likely to have needed significant resuscitation at birth. Respiratory distress was the most common reason for NICU admission. None of the NICU-admitted neonates were SARS-CoV-2-positive. There were no differences between the values of the complete blood counts, morbidities at discharge, lengths of hospitalization, or rates of readmission to hospital in the first month of life observed between the two groups. Conclusions: The vertical transmission of the SARS-CoV-2 infection remains rare; there was no difference in the hospital outcomes in the neonates of infected mothers. Unlike other studies, which show an increased tendency toward preterm birth in SARS-CoV-2-positive mothers, our study indicates no such association.

Intrauterine Vertical Transmission of SARS-CoV-2 Infection Among Confirmed Cases of Pregnant Women: “A Double Burden for the Pregnant Women”—A Systematic Review

Introduction. The world health organization (WHO) has declared the outbreak of novel coronavirus (2019-nCoV), which is now known as Coronavirus Disease 2019 (COVID-19). Whereas, its quick global spread has resulted in a worldwide pandemic. The present review article was intended to evaluate intrauterine vertical transmission of SARS-CoV-2 infection among confirmed cases of pregnant women. Methods. Web of Science, EMBASE, PubMed, African Journals OnLine, Scopus, PsycINFO, HINARI, Cochrane Library, Wiley Online Library, and Google scholar were used for search. Result. A total of 43 articles were included in to this systematic review. A total of 1,300 neonates born from pregnant women confirmed for COVI-19 were tested for SARS-CoV-2 infection by real-time reverse transcriptase–polymerase chain reaction (RT-PCR). From the 1,300 neonates tested for SARS-CoV-2 infection, 93 neonates were found positive for this infection by RT-PCR. From this systematic review finding, the vertical transmission rate of SARS-CoV-2 infection was 7.15%. This pandemic has stressed the entire public, particularly pregnant women and healthcare providers, while it challenged antenatal care and postnatal care by far. Thus, even being under lockdown in the middle of a global pandemic is stressful enough. Therefore, imagine the added burden of being pregnant, which could be a double burden for these women. Conclusion. There is no concrete evidence of vertical transmission of SARS-CoV-2. Therefore, due to the limited number of clinical evidences, obstetricians, pediatricians, and other healthcare providers should continuously update their knowledge and be conscious about the transmission of SARS-CoV-2 vertically during pregnancy.

The Impact of the SARS-CoV-2 Pandemic on Reproduction, Sexual Function and Behaviors: A Review of the Main Trends and Findings

Objective: This review sought to describe the main trends and findings on the SARS-CoV-2 and the pandemic's effect on reproduction (i.e., effects on fertility, reproductive tissue, pregnancy, vertical and sexual transmission) and sexual function and behaviors. Methods: A review was conducted on studies assessing these variables through the Scopus and PubMed databases between the years 2019-2021. Results: Results showed SARS-CoV-2 pandemic and social distancing measures have affected-and in some cases not-different aspects of people's reproductive function, sexual function and behaviors. Conclusions: Suggestions are offered for researchers and professionals focused on future research and clinical practice.

Impact of SARS-CoV-2 on pregnancy and neonatal outcomes: An open prospective study of pregnant women in Brazil

OBJECTIVES

To determine the incidence and risk of adverse obstetric and neonatal outcomes according to SARS-CoV-2 infection severity in pregnant women.

METHOD

Open prospective study of pregnant women tested for SARS-CoV-2 by serological and molecular assays during pregnancy or delivery in two hospitals in Sao Paulo, Brazil from April 12, 2020, to February 28, 2021. Five groups were considered for analysis: C0, negative COVID-19 results and no COVID-19 symptoms; C1, positive COVID-19 results, and no symptoms; C2, positive COVID-19 results with mild symptoms; C3, positive COVID-19 results with moderate symptoms; and C4, positive COVID-19 results with severe symptoms. The association between obstetric and neonatal outcomes and COVID-19 severity was determined using multivariate analysis.

RESULTS

734 eligible pregnant women were enrolled as follows: C0 (n = 357), C1 (n = 127), C2 (n = 174), C3 (n = 37), and C4 (n = 39). The following pregnancy and neonatal outcomes were associated with severe COVID-19: oligohydramnios (adjusted Odds Ratio [aOR] = 6.18; 95% CI 1.87‒20.39), fetal distress (aOR = 4.01; 95% Confidence Interval [CI] 1.84‒8.75), preterm birth (aOR = 5.51; 95% CI 1.47‒20.61), longer hospital stay (aOR = 1.66; 95% CI 1.36‒2.02), and admission to the neonatal intensive care unit (aOR = 19.36; 95% CI, 5.86‒63.99). All maternal (n = 6, 15.4%, p < 0.001) and neonatal (n = 5, 12.5%, p < 0.001) deaths and most fetal deaths (n = 4, 9.8%, p < 0.001) occurred in C4 group. Moderate COVID-19 was associated with oligohydramnios (aOR = 6.23; 95% CI 1.93‒20.13) and preterm birth (aOR = 3.60; 95% CI 1.45‒9.27). Mild COVID-19 was associated with oligohydramnios (aOR = 3.77; 95% CI 1.56‒9.07).

CONCLUSION

Adverse pregnancy and neonatal outcomes were associated with maternal symptomatic COVID-19 status, and risk increased with disease severity.

COVID-19 and vertical transmission: assessing the expression of ACE2/TMPRSS2 in the human fetus and placenta to assess the risk of SARS-CoV-2 infection

BACKGROUND

Pregnant women have been identified as a potentially at-risk group concerning COVID-19 infection, but little is known regarding the susceptibility of the fetus to infection. Co-expression of ACE2 and TMPRSS2 has been identified as a prerequisite for infection, and expression across different tissues is known to vary between children and adults. However, the expression of these proteins in the fetus is unknown.

METHODS

We performed a retrospective analysis of a single cell data repository. The data were then validated at both gene and protein level by performing RT-qPCR and two-colour immunohistochemistry on a library of second-trimester human fetal tissues.

FINDINGS

TMPRSS2 is present at both gene and protein level in the predominantly epithelial fetal tissues analysed. ACE2 is present at significant levels only in the fetal intestine and kidney, and is not expressed in the fetal lung. The placenta also does not co-express the two proteins across the second trimester or at term.

INTERPRETATION

This dataset indicates that the lungs are unlikely to be a viable route of SARS-CoV2 fetal infection. The fetal kidney, despite presenting both the proteins required for the infection, is anatomically protected from the exposure to the virus. However, the gastrointestinal tract is likely to be susceptible to infection due to its high co-expression of both proteins, as well as its exposure to potentially infected amniotic fluid.

TWEETABLE ABSTRACT

This work provides detailed mechanistic insight into the relative protection & vulnerabilities of the fetus & placenta to SARS-CoV-2 infection by scRNAseq & protein expression analysis for ACE2 & TMPRSS2. The findings help to explain the low rate of vertical transmission.

Unique Severe COVID-19 Placental Signature Independent of Severity of Clinical Maternal Symptoms

BACKGROUND

Although the risk for transplacental transmission of SARS-CoV-2 is rare, placental infections with adverse functional consequences have been reported. This study aims to analyse histological placental findings in pregnancies complicated by SARS-CoV-2 infection and investigate its correlation with clinical symptoms and perinatal outcomes. We want to determine which pregnancies are at-risk to prevent adverse pregnancy outcomes related to COVID-19 in the future.

METHODS

A prospective, longitudinal, multicentre, cohort study. All pregnant women presenting between April 2020 and March 2021 with a nasopharyngeal RT-PCR-confirmed SARS-CoV-2 infection were included. Around delivery, maternal, foetal and placental PCR samples were collected. Placental pathology was correlated with clinical maternal characteristics of COVID-19.

RESULTS

Thirty-six patients were included, 33 singleton pregnancies (n = 33, 92%) and three twin pregnancies (n = 3, 8%). Twenty-four (62%) placentas showed at least one abnormality. Four placentas (4/39, 10%) showed placental staining positive for the presence of SARS-CoV-2 accompanied by a unique combination of diffuse, severe inflammatory placental changes with massive perivillous fibrin depositions, necrosis of syncytiotrophoblast, diffuse chronic intervillositis, and a specific, unprecedented CD20+ B-cell infiltration. This SARS-CoV-2 placental signature seems to correlate with foetal distress (75% vs. 15.6%, p = 0.007) but not with the severity of maternal COVID-19 disease.

CONCLUSION

We describe a unique placental signature in pregnant patients with COVID-19, which has not been reported in a historical cohort. We show that the foetal environment can be seriously compromised by disruption of placental function due to local, devastating SARS-CoV-2 infection. Maternal clinical symptoms did not predict the severity of the SARS-CoV-2-related placental signature, resulting in a lack of adequate identification of maternal criteria for pregnancies at risk. Close foetal monitoring and pregnancy termination in case of foetal distress can prevent adverse pregnancy outcomes due to COVID-19 related placental disease.