Assessment of Maternal and Neonatal SARS-CoV-2 Viral Load, Transplacental Antibody Transfer, and Placental Pathology in Pregnancies During the COVID-19 Pandemic

COVID-19 disease and vaccination in pregnant and lactating women

Background

More than 325,000 cases of coronavirus disease 2019 (COVID‐19) have been reported among pregnant women in the Americas.

Aims

This review examines the impact of COVID‐19 in pregnant women and describes available evidence on the safety, effectiveness, and immune response(s) to vaccination among pregnant and lactating women.

Content

Multiple studies indicate that pregnant women are more susceptible to adverse COVID‐19 outcomes, including hospitalization, intensive care unit admission, and invasive ventilation than non‐pregnant women with COVID‐19. Furthermore, COVID‐19 in pregnancy is associated with adverse maternal and neonatal outcomes. Adverse COVID‐19 outcomes appear to disproportionately affect pregnant women from low‐ and middle‐income countries, likely reflecting inequities in access to quality healthcare. Despite the absence of safety and efficacy data from randomized clinical trials in this subpopulation, observational studies and data from pregnancy registries thus far have demonstrated that vaccination of pregnant or lactating women against COVID‐19 is safe, effective, and results in robust immune responses including transfer of antibodies to the newborn via the placenta and breast milk, respectively.

Implications

These data support vaccination recommendations intending to help protect these vulnerable individuals against COVID‐19 and its sequelae. Randomized clinical studies will further evaluate the safety and immunogenicity of COVID‐19 vaccines in these populations. This review examines the impact of COVID‐19 in pregnant women and describes available evidence on the safety, effectiveness, and immune response(s) to vaccination among pregnant and lactating women.

Clinical manifestations of SARS-CoV-2 infection in neonates and the probability of maternal transmission

AIM

This study aimed to measure the incidence of SARS-CoV-2 infection in neonates from infected mothers and to screen disease severity in neonates.

METHODS

We conducted a population-based cohort study of neonates from SARS-CoV-2-positive mothers, enrolling mothers who tested positive for SARS-CoV-2 and their neonates. Eleven infants <25 days old presenting with SARS-CoV-2 infection were also included in the study. We recorded clinical symptoms of SARS-CoV-2-positive mothers and their neonates.

RESULTS

One of 126 babies born to SARS-CoV-2-infected mothers was found to be positive (0.79%). The referred positive neonates were either asymptomatic or suffered from symptoms ranging from mild respiratory distress to pneumonia. Most SARS-CoV-2-positive neonates showed neutropenia and lymphocytosis. Most of the SARS-CoV-2-infected mothers (n = 126) were either asymptomatic (46, 36.5%) or showed mild respiratory distress (66, 52.4%). However, pneumonia and severe respiratory distress were reported in 14 (11.1%) of the SARS-CoV-2-infected mothers. There were no deaths of either SARS-CoV-2-infected mothers or neonates.

CONCLUSION

We conclude that mothers transmitted infection to their neonates at a very low rate. Disease in neonates is usually mild, although some babies have severe disease. SARS-CoV-2 infection in late pregnancy usually leads to mild maternal disease, but severe disease is reported in approximately one-tenth of the infected women.

Distinct Cellular Immune Responses to SARS-CoV-2 in Pregnant Women

Pregnant women are at increased risk of adverse outcomes, including preeclampsia and preterm birth, that may result from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Pregnancy imprints specific maternal immune responses that can modulate host susceptibility to microbial infection; therefore, recent studies have focused on the humoral response against SARS-CoV-2 in pregnant women. However, the pregnancy-specific cellular immune responses triggered by SARS-CoV-2 infection are poorly understood. In this study, we undertook an extensive in vitro investigation to determine the cellular immune responses to SARS-CoV-2 particles and proteins/peptides in pregnant women. First, we show that SARS-CoV-2 particles do not alter the pregnancy-specific oxidative burst of neutrophils and monocytes. Yet, SARS-CoV-2 particles/proteins shift monocyte activation from the classical to intermediate states in pregnant, but not in nonpregnant, women. Furthermore, SARS-CoV-2 proteins, but not particles or peptide pools, mildly enhance T cell activation during pregnancy. As expected, B cell phenotypes are heavily modulated by SARS-CoV-2 particles in all women; yet, pregnancy itself further modified such responses in these adaptive immune cells. Lastly, we report that pregnancy itself governs cytokine responses in the maternal circulation, of which IFN-β and IL-8 were diminished upon SARS-CoV-2 challenge. Collectively, these findings highlight the differential in vitro responses to SARS-CoV-2 in pregnant and nonpregnant women and shed light on the immune mechanisms implicated in coronavirus disease 2019 during pregnancy.

COVID-19 in pregnancy: implications for fetal brain development

The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during pregnancy on the developing fetal brain is poorly understood. Other antenatal infections such as influenza have been associated with adverse neurodevelopmental outcomes in offspring. Although vertical transmission has been rarely observed in SARS-CoV-2 to date, given the potential for profound maternal immune activation (MIA), impact on the developing fetal brain is likely. Here we review evidence that SARS-CoV-2 and other viral infections during pregnancy can result in maternal, placental, and fetal immune activation, and ultimately in offspring neurodevelopmental morbidity. Finally, we highlight the need for cellular models of fetal brain development to better understand potential short- and long-term impacts of maternal SARS-CoV-2 infection on the next generation.

Low-level SARS-CoV-2 viremia coincident with COVID placentitis and stillbirth

SARS-CoV-2 infection in pregnancy and COVID placentitis are associated with an increased risk of stillbirth. We sought to investigate the presence of maternal viremia in people with SARS-CoV-2 infection during pregnancy who had histologic placentitis versus those without placentitis. SARS-CoV-2 qRT-PCR was performed on plasma from 6 patients with COVID placentitis and 12 matched controls without placentitis. SARS-CoV-2 infection occurred between 4/2020–1/2021; the latency between SARS-CoV-2 diagnosis and delivery was 0–76 days. Two placentitis cases demonstrated viremia (1 stillbirth and 1 well infant), while 12/12 controls were negative. Future research may consider viremia as a possible marker of COVID placentitis.

Single-cell immunophenotyping of the fetal immune response to maternal SARS-CoV-2 infection in late gestation

BACKGROUND

During the COVID-19 pandemic, thousands of pregnant women have been infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The implications of maternal SARS-CoV-2 infection on fetal and childhood well-being need to be characterized. We aimed to characterize the fetal immune response to maternal SARS-CoV-2 infection.

METHODS

We performed single-cell RNA-sequencing and T cell receptor sequencing on cord blood mononuclear cells (CBMCs) from newborns of mothers infected with SARS-CoV-2 in the third trimester (cases) or without SARS-CoV-2 infection (controls).

RESULTS

We identified widespread gene expression changes in CBMCs from cases, including upregulation of interferon-stimulated genes and major histocompatibility complex genes in CD14+ monocytes, transcriptional changes suggestive of activation of plasmacytoid dendritic cells, and activation and exhaustion of natural killer cells. Lastly, we observed fetal T cell clonal expansion in cases compared to controls.

CONCLUSIONS

As none of the infants were infected with SARS-CoV-2, our results suggest that maternal SARS-CoV-2 infection might modulate the fetal immune system in the absence of vertical transmission.

IMPACT

The implications of maternal SARS-CoV-2 infection in the absence of vertical transmission on fetal and childhood well-being are poorly understood. Maternal SARS-CoV-2 infection might modulate the fetal immune system in the absence of vertical transmission. This study raises important questions about the untoward effects of maternal SARS-CoV-2 on the fetus, even in the absence of vertical transmission.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Pregnancy. A Non-systematic Review of Clinical Presentation, Potential Effects of Physiological Adaptations in Pregnancy, and Placental Vascular Alterations

In December 2019, the novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) rapidly spread to become a pandemic. To date, increasing evidence has described the potential negative impact of SARS-CoV-2 infection on pregnant women. Although the pathophysiology of coronavirus disease 2019 (COVID-19) is not entirely understood, there is emerging evidence that it causes a severe systemic inflammatory response associated with vascular alterations that could be of special interest considering some physiological changes in pregnancy. Additionally, these alterations may affect the physiology of the placenta and are associated with pregnancy complications and abnormal histologic findings. On the other hand, data about the vaccine against SARS-CoV-2 are limited, but the risks of administering COVID-19 vaccines during pregnancy appear to be minimal. This review summarizes the current literature on SARSCoV2 virus infection, the development of COVID-19 and its relationship with physiological changes, and angiotensin-converting enzyme 2 (ACE2) function during pregnancy. We have particularly emphasized evidence coming from Latin American countries.

Obstetric and perinatal outcomes of pregnancies with COVID 19: a systematic review and meta-analysis

OBJECTIVE

This meta-analysis aimed at comparing obstetric and perinatal outcomes in laboratory-tested pregnant women for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection before delivering.

METHOD

We performed a comprehensive systematic review of electronic databases for studies reporting pregnant women with and without SARS-CoV-2 infection, as determined by polymerase chain reaction (PCR) before delivery, during the pandemic period published up to June 25, 2021. Results are reported as mean difference (MD) or odds ratio (OR) and their 95% confidence interval (CI).

RESULTS

Seventeen observational studies with low to moderate risk of bias, reported on 2,769 pregnant women with a positive SARS-CoV-2 PCR test and 13,807 with a negative test. Pregnant women with a positive PCR test delivered at an earlier gestational age (MD -0.19; 95% CI -0.36 to -0.02 weeks), smoked less (OR 0.75; 95% CI 0.61-0.94) and were associated with higher odds for preeclampsia (OR 1.30; 95% CI 1.09-1.54), NICU admissions (OR 2.37; 95% CI 1.18-4.76), stillbirths (OR 2.70; 95% CI, 1.38-5.29), and perinatal mortality (OR 3.23; 95% CI 1.23-8.52). There were no significant differences between positive and negative tested women in terms of nulliparity, multiple pregnancies, gestational diabetes, route of delivery, labor induction, preterm birth, infant birth weight, 5 min Apgar scores < 7, small-for-gestational-age infants and fetal malformations. Eleven studies included neonatal PCR SARS-CoV-2 testing which was performed on 129 infants, of which 20 were positive.

CONCLUSION

Positive SARS-CoV-2 tested pregnant women had higher odds for preeclampsia/hypertensive disorders of pregnancy, NICU admissions, stillbirths and perinatal mortality.

Is There a Role for SARS-CoV-2/COVID-19 on the Female Reproductive System?

Coronavirus disease (COVID-19) has emerged as a very serious pandemic caused by the rapidly evolving transmission of the coronavirus SARS-CoV-2. Since its outbreak in 2020, the SARS CoV-2 has represented an important challenge for the physicians due to its well known respiratory sequelae. To date, the role of SARS-CoV-2 infection on organs and systems other than lungs and respiratory tract remains less clear. In particular, it remains to be investigated whether the reproductive system can be affected by the SARS-CoV-2 in the long term-period or, in alternative, drugs used to treat COVID-19 might impact the reproductive systems and, in turn, fertility. What is known is that SARS-Cov-2 binds to target cells of host through different receptors including angiotensin-converting enzyme 2 (ACE2), neuropilin-1, AXL and antibody-FcɣR complexes. ACE2 physiologically regulates both the expression of angiotensin II (Ang II) as well as Ang-(1-7) to exerts its physiological functions. The reproductive system abundantly expresses ACE2 and produces Ang-(1-7), starting from precursors which are locally generated or derived from systemic circulation. Ang-(1-7) plays an important role of stimulus to the growth and maturation of ovarian follicle as well as to ovulation. Also human endometrium expresses Ang-(1-7), mainly during the post-ovulatory phase. Animal and human observational studies demonstrated that Ang-(1-7) is involved in the maternal immune response to pregnancy and its deficiency is associated with a defective placenta development. In our manuscript, we review the current knowledge about whether SARS-CoV-2 may impact the female reproductive system. We further explain the possible molecular mechanism by which SARS-CoV-2 might affect ovarian, endometrial and female genital tract cells.

SARS-CoV-2 Placentitis Associated With B.1.617.2 (Delta) Variant and Fetal Distress or Demise

There is limited information on the specific impact of maternal infection with the SARS-CoV-2 B.1.617.2 (delta) variant on pregnancy outcomes. We present 2 cases of intrauterine fetal demise and 1 case of severe fetal distress in the setting of maternal infection with delta-variant SARS-CoV-2. In all cases, fetal demise or distress occurred within 14 days of COVID-19 diagnosis. Evaluation revealed maternal viremia, high nasopharyngeal viral load, evidence of placental infection with delta-variant SARS-CoV-2, and hallmark features of SARS-CoV-2 placentitis. We suggest that delta-variant SARS-CoV-2 infection during pregnancy warrants vigilance for placental dysfunction and fetal compromise regardless of disease severity.

Coronavirus Disease 2019 Infection in Newborns

Maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can present with or without symptoms at the time of birth. Symptomatic mothers are more likely be associated with preterm births. Population studies demonstrate a consistent association of SARS-CoV-2 infection and a reduction in preterm birth rate. Newborns with positive SARS-CoV-2 test results appear to have minimal burden of illness that is directly associated with a viral infection. Neonatal mortality directly related to SARS-CoV-2 is extremely rare. Maternal vaccination in pregnant women leads to maternal antibody production, and this can occur as early as 5 days after the first vaccination dose.

Vertical Transmission and Neonatal Outcomes Following Maternal SARS-CoV-2 Infection During Pregnancy

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected over 200 million people worldwide and has likely exposed millions of neonates to SARS-CoV-2 in utero. A large body of literature has examined the possibility of vertical transmission from pregnant women infected with SARS-CoV-2 to their neonates. In this chapter, we review mechanisms of-and evidence for-vertical transmission of SARS-CoV-2, including transplacental, through other biospecimens and breastfeeding, and discuss neonatal outcomes following in utero exposure. Based on the available literature, we conclude vertical transmission of SARS-CoV-2 is rare, and exposed neonates generally show favorable health outcomes.

Detection of SARS-CoV-2 in Neonatal Autopsy Tissues and Placenta

Severe coronavirus disease in neonates is rare. We analyzed clinical, laboratory, and autopsy findings from a neonate in the United States who was delivered at 25 weeks of gestation and died 4 days after birth; the mother had asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and preeclampsia. We observed severe diffuse alveolar damage and localized SARS-CoV-2 by immunohistochemistry, in situ hybridization, and electron microscopy of the lungs of the neonate. We localized SARS-CoV-2 RNA in neonatal heart and liver vascular endothelium by using in situ hybridization and detected SARS-CoV-2 RNA in neonatal and placental tissues by using reverse transcription PCR. Subgenomic reverse transcription PCR suggested viral replication in lung/airway, heart, and liver. These findings indicate that in utero SARS-CoV-2 transmission contributed to this neonatal death.

mRNA Covid-19 vaccines in pregnancy: A systematic review

OBJECTIVE

Pregnancy is a known risk factor for severe Coronavirus disease 2019. It is important to develop safe vaccines that elicit strong maternal and fetal antibody responses.

METHODS

Registries (ClinicalTrials.gov, the WHO Clinical Trial Registry, and the European Union Clinical Trial Registry) and databases (MEDLINE, ScienceDirect, Cochrane Library, Proquest, Springer, medRxiv, and bioRxiv) were systematically searched in June 20-22, 2021, for research articles pertaining to Covid-19 and pregnancy. Manual searches of bioRxiv and medRxiv were also conducted. Inclusion criteria were studies that focused on Covid-19 vaccination among pregnant women, while review articles and non-human studies were excluded. Infection rate, maternal antibody response, transplacental antibody transfer, and adverse events were described.

RESULTS

There were 13 observational studies with a total of 48,039 pregnant women who received mRNA vaccines. Of those, three studies investigated infection rate, six studies investigated maternal antibody response, seven studies investigated antibody transfer, three studies reported local adverse events, and five studies reported systemic adverse events. The available data suggested that the mRNA-based vaccines (Pfizer-BioNTech and Moderna) can prevent future SARS-CoV-2 infection. These vaccines did not show clear harm in pregnancy. The most commonly encountered adverse reactions were pain at the injection site, fatigue, and headache, but these were transient. Antibody responses were rapid after the first vaccine dose. After the booster, antibody responses were stronger and associated with better transplacental antibody transfer. Longer intervals between first vaccination dose and delivery were also associated with higher antibody fetal IgG and a better antibody transfer ratio.

CONCLUSIONS

The SARS-CoV-2 mRNA vaccines are encouraged for pregnancy. These vaccines can be a safe option for pregnant women and their fetuses. Two vaccine doses are recommended for more robust maternal and fetal antibody responses. Longer latency is associated with higher fetal antibody responses. Further research about its long-term effect on pregnancy is needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42021261684).

An update on COVID-19 and pregnancy

Physiological, mechanical, and immunologic alterations in pregnancy could potentially affect the susceptibility to and the severity of COVID-19 during pregnancy. Owing to the lack of comparable incidence data and the challenges with disentangling differences in the susceptibility from different exposure risks, the data are insufficient to determine whether pregnancy increases the susceptibility to SARS-CoV-2 infection. The data support pregnancy as a risk factor for severe disease associated with COVID-19; some of the best evidence comes from the United States Centers for Disease Control and Prevention COVID-19 surveillance system, which reported that pregnant persons were more likely to be admitted to an intensive care unit, require invasive ventilation, require extracorporeal membrane oxygenation, and die than nonpregnant women of reproductive age. Although the intrauterine transmission of SARS-CoV-2 has been documented, it appears to be rare. It is possibly related to low levels of SARS-CoV-2 viremia and the decreased coexpression of angiotensin-converting enzyme 2 and transmembrane serine protease 2 needed for SARS-CoV-2 entry into cells in the placenta. Evidence is accumulating that SARS-CoV-2 infection during pregnancy is associated with a number of adverse pregnancy outcomes including preeclampsia, preterm birth, and stillbirth, especially among pregnant persons with severe COVID-19 disease. In addition to the direct impact of COVID-19 on pregnancy outcomes, there is evidence that the pandemic and its effects on healthcare systems have had adverse effects such as increased stillbirths and maternal deaths on the pregnancy outcomes. These trends may represent widening disparities and an alarming reversal of recent improvements in maternal and infant health. All the 3 COVID-19 vaccines currently available in the United States can be administered to pregnant or lactating persons, with no preference for the vaccine type. Although the safety data in pregnancy are rapidly accumulating and no safety signals in pregnancy have been detected, additional information about the birth outcomes, particularly among persons vaccinated earlier in pregnancy, are needed.

COVID-19 Infection in Pregnancy: Obstetrical Risk Factors and Neonatal Outcomes-A Monocentric, Single-Cohort Study

The effects of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 on pregnant women and neonates are mainly unknown, since limited data are available in the literature. We conducted a monocentric and cross-sectional study enrolling 122 un-vaccinated pregnant women with COVID-19 infection tested by RT-PCR nasopharyngeal swab. Only 4.1% of the patients had severe COVID-19 symptoms together with major respiratory symptoms and intensive care unit admission, whereas 35.25% of women had comorbidities and two-thirds of them were overweight or obese. COVID-19 was detected mainly in the third trimester (98.36%) and multiparous women (59.02%). The mode of delivery was influenced by mild-severe COVID-19 symptoms, with a higher number of urgent or emergent cesarean sections than spontaneous or operative vaginal births. Preterm births were associated with high BMI, mode of delivery (higher among cesarean sections), nulliparity, and severe COVID-19 symptoms. In cases of severe COVID-19 symptoms, there was a higher rate of respiratory distress syndrome among newborns. In the end, only the presence of a severe COVID-19 infection worsened the obstetrical and neonatal outcomes, with higher rates of urgent or emergent cesarean section, preterm births, and neonatal respiratory distress syndrome.

Delayed Antiviral Immune Responses in Severe Acute Respiratory Syndrome Coronavirus Infected Pregnant Mice

Sex differences in immune responses had been reported to correlate with different symptoms and mortality in the disease course of coronavirus disease 2019 (COVID-19). However, whether severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection interferes with females’ fertility and causes different symptoms among pregnant and non-pregnant females remains unknown. Here, we examined the differences in viral loads, SARS-CoV-2-specific antibody titers, proinflammatory cytokines, and levels of T cell activation after SARS-CoV-2 sub-lethal infection between pregnant and non-pregnant human Angiotensin-Converting Enzyme II (ACE2) transgenic mouse models. Both mice showed elevated levels of viral loads in the lung at 4 days post-infection (dpi). However, viral loads in the pregnant group remained elevated at 7 dpi while decreased in the non-pregnant group. Consistent with viral loads, increased production of proinflammatory cytokines was detected from the pregnant group, and the IgM or SARS-CoV-2-specific IgG antibody in serum of pregnant mice featured delayed elevation compared with non-pregnant mice. Moreover, by accessing kinetics of activation marker expression of peripheral T cells after infection, a lower level of CD8+ T cell activation was observed in pregnant mice, further demonstrating the difference of immune-response between pregnant and non-pregnant mice. Although vertical transmission did not occur as SARS-CoV-2 RNA was absent in the uterus and fetus from the infected pregnant mice, a lower pregnancy rate was observed when the mice were infected before embryo implantation after mating, indicating that SARS-CoV-2 infection may interfere with mice’s fertility at a specific time window. In summary, pregnant mice bear a weaker ability to eliminate the SARS-CoV-2 virus than non-pregnant mice, which was correlated with lower levels of antibody production and T cell activation.

Maternal-fetal immune responses in pregnant women infected with SARS-CoV-2

Pregnant women represent a high-risk population for severe/critical COVID-19 and mortality. However, the maternal-fetal immune responses initiated by SARS-CoV-2 infection, and whether this virus is detectable in the placenta, are still under investigation. Here we show that SARS-CoV-2 infection during pregnancy primarily induces unique inflammatory responses at the maternal-fetal interface, which are largely governed by maternal T cells and fetal stromal cells. SARS-CoV-2 infection during pregnancy is also associated with humoral and cellular immune responses in the maternal blood, as well as with a mild cytokine response in the neonatal circulation (i.e., umbilical cord blood), without compromising the T-cell repertoire or initiating IgM responses. Importantly, SARS-CoV-2 is not detected in the placental tissues, nor is the sterility of the placenta compromised by maternal viral infection. This study provides insight into the maternal-fetal immune responses triggered by SARS-CoV-2 and emphasizes the rarity of placental infection.

The Different Immune Responses by Age Are due to the Ability of the Fetal Immune System to Secrete Primal Immunoglobulins Responding to Unexperienced Antigens

Among numerous studies on coronavirus 2019 (COVID-19), we noted that the infection and mortality rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) increased with age and that fetuses known to be particularly susceptible to infection were better protected despite various mutations. Hence, we established the hypothesis that a new immune system exists that forms before birth and decreases with aging.

Methods: To prove this hypothesis, we established new ex-vivo culture conditions simulating the critical environmental factors of fetal stem cells (FSCs) in early pregnancy. Then, we analyzed the components from FSCs cultivated newly developed ex-vivo culture conditions and compared them from FSCs cultured in a normal condition.

Results: We demonstrated that immunoglobulin M (IgM), a natural antibody (NAb) produced only in early B-1 cells, immunoglobulins (Igs) including IgG3, which has a wide range of antigen-binding capacity and affinity, complement proteins, and antiviral proteins are induced in FSCs only cultured in newly developed ex-vivo culture conditions. Particularly we confirmed that their extracellular vesicles (EVs) contained NAbs, Igs, various complement proteins, and antiviral proteins, as well as human leukocyte antigen G (HLA-G), responsible for immune tolerance.

Conclusion: Our results suggest that FSCs in early pregnancy can form an independent immune system responding to unlearned antigens as a self-defense mechanism before establishing mature immune systems. Moreover, we propose the possibility of new solutions to cope with various infectious diseases based on the factors in NAbs-containing EVs, especially not causing unnecessary immune reaction due to HLA-G.

Cord Blood SARS-CoV-2 IgG Antibodies and Their Association With Maternal Immunity and Neonatal Outcomes

Passive transplacental immunity is crucial for neonatal protection from infections. Data on the correlation between neonatal immunity to SARS-CoV-2 and protection from adverse outcomes is scarce. This work aimed to describe neonatal seropositivity in the context of maternal SARS-CoV-2 infection, seropositivity, and neonatal outcomes. This retrospective nested case-control study enrolled high-risk pregnant women with a SARS-CoV-2 RT-PCR positive test who gave birth at the Instituto Nacional de Perinatología in Mexico City and their term neonates. Anti-SARS-CoV-2 IgG antibodies in maternal and cord blood samples were detected using a chemiluminescent assay. In total, 63 mother-neonate dyads (mean gestational age 38.4 weeks) were included. Transplacental transfer of SARS-CoV-2 IgG occurred in 76% of neonates from seropositive mothers. A positive association between maternal IgG levels and Cycle threshold (Ct) values of RT-qPCR test for SARS-CoV-2 with neonatal IgG levels was observed. Regarding neonatal outcomes, most seropositive neonates did not require any mechanical ventilation, and none developed any respiratory morbidity (either in the COVID-19 positive or negative groups) compared to 7 seronegative neonates. Furthermore, the odds of neonatal respiratory morbidity exhibited a tendency to decrease when neonatal IgG levels increase. These results add further evidence suggesting passive IgG transfer importance.

Neonates and COVID-19: state of the art : Neonatal Sepsis series

The SARS-CoV-2 pandemic has had a significant impact worldwide, particularly in middle- and low-income countries. While this impact has been well-recognized in certain age groups, the effects, both direct and indirect, on the neonatal population remain largely unknown. There are placental changes associated, though the contributions to maternal and fetal illness have not been fully determined. The rate of premature delivery has increased and SARS-CoV-2 infection is proportionately higher in premature neonates, which appears to be related to premature delivery for maternal reasons rather than an increase in spontaneous preterm labor. There is much room for expansion, including long-term data on outcomes for affected babies. Though uncommon, there has been evidence of adverse events in neonates, including Multisystem Inflammatory Syndrome in Children, associated with COVID-19 (MIS-C). There are recommendations for reduction of viral transmission to neonates, though more research is required to determine the role of passive immunization of the fetus via maternal vaccination. There is now considerable evidence suggesting that the severe visitation restrictions implemented early in the pandemic have negatively impacted the care of the neonate and the experiences of both parents and healthcare professionals alike. Ongoing collaboration is required to determine the full impact, and guidelines for future management. IMPACT: Comprehensive review of current available evidence related to impact of the COVID-19 pandemic on neonates, effects on their health, impact on their quality of care and indirect influences on their clinical course, including comparisons with other age groups. Reference to current evidence for maternal experience of infection and how it impacts the fetus and then neonate. Outline of the need for ongoing research, including specific areas in which there are significant gaps in knowledge.

SARS-CoV-2 infection and neonates: Evidence-based data after 18 months of the pandemic

After 18 months of the COVID-19 pandemic, data concerning SARS-CoV-2 infection in pregnant women and their neonates are progressively taking the place of complete uncertainty. Here, we summarize updated evidence regarding several critical aspects of perinatal SARS-CoV-2 infection, including 1) vertical transmission of the virus in utero, which is possible but seems rare according to current epidemiological data; 2) how COVID-19 during pregnancy can shape maternal and neonatal outcomes, either directly or indirectly; 3) how recommendations regarding the management of infected dyads have been progressively modified in light of new scientific evidence; and 4) how maternal infection or vaccination can induce the passive protection of fetuses and neonates against the infection, through the transfer of specific antibodies before and after birth.

Effects of COVID-19 and mRNA vaccines on human fertility

The coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has precipitated a global health crisis of unprecedented proportions. Because of its severe impact, multiple COVID-19 vaccines are being rapidly developed, approved and manufactured. Among them, mRNA vaccines are considered as ideal candidates with special advantages to meet this challenge. However, some serious adverse events have been reported after their application, significantly increasing concerns about the safety and efficacy of the vaccines and doubts about the necessity of vaccination. Although several fertility societies have announced that COVID-19 mRNA vaccines are unlikely to affect fertility, there is no denying that the current evidence is very limited, which is one of the reasons for vaccine hesitancy in the population, especially in pregnant women. Herein, we provide an in-depth discussion on the involvement of the male and female reproductive systems during SARS-CoV-2 infection or after vaccination. On one hand, despite the low risk of infection in the male reproductive system or fetus, COVID-19 could pose an enormous threat to human reproductive health. On the other hand, our review indicates that both men and women, especially pregnant women, have no fertility problems or increased adverse pregnancy outcomes after vaccination, and, in particular, the benefits of maternal antibodies transferred through the placenta outweigh any known or potential risks. Thus, in the case of the rapid spread of COVID-19, although further research is still required, especially a larger population-based longitudinal study, it is obviously a wise option to be vaccinated instead of suffering from serious adverse symptoms of virus infection.

Global Perspectives on Immunization Against SARS-CoV-2 During Pregnancy and Priorities for Future Research: An International Consensus Paper From the World Association of Infectious Diseases and Immunological Disorders

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in pregnancy is associated with a higher risk for severe morbidity and mortality when compared with infection in non-pregnant women of childbearing age. An increasing number of countries recommend immunization against SARS-CoV-2 in pregnant women. Recent studies provide preliminary and supportive evidence on safety, immunogenicity and effectiveness of coronavirus disease 2019 (COVID-19) vaccines in pregnant women; however, important knowledge gaps remain which warrant further studies. This collaborative consensus paper provides a review of the current literature on COVID-19 vaccines in pregnant women, identifies knowledge gaps and outlines priorities for future research to optimize protection against SARS-CoV-2 in the pregnant women and their infants.

Intrauterine Fetal Demise After Uncomplicated COVID-19: What Can We Learn from the Case?

Background: SARS-CoV-2 infection in pregnant women can lead to placental damage and transplacental infection transfer, and intrauterine fetal demise is an unpredictable event. Case study: A 32-year-old patient in her 38th week of pregnancy reported loss of fetal movements. She overcame mild COVID-19 with positive PCR test 22 days before. A histology of the placenta showed deposition of intervillous fibrinoid, lympho-histiocytic infiltration, scant neutrophils, clumping of villi, and extant infarctions. Immunohistochemistry identified focal SARS-CoV-2 nucleocapsid and spike protein in the syncytiotrophoblast and isolated in situ hybridization of the virus’ RNA. Low ACE2 and TMPRSS2 contrasted with strong basigin/CD147 and PDL-1 positivity in the trophoblast. An autopsy of the fetus showed no morphological abnormalities except for lung interstitial infiltrate, with prevalent CD8-positive T-lymphocytes and B-lymphocytes. Immunohistochemistry and in situ hybridization proved the presence of countless dispersed SARS-CoV-2-infected epithelial and endothelial cells in the lung tissue. The potential virus-receptor protein ACE2, TMPRSS2, and CD147 expression was too low to be detected. Conclusion: Over three weeks’ persistence of trophoblast viral infection lead to extensive intervillous fibrinoid depositions and placental infarctions. High CD147 expression might serve as the dominant receptor for the virus, and PDL-1 could limit maternal immunity in placental tissue virus clearance. The presented case indicates that the SARS-CoV-2 infection-induced changes in the placenta lead to ischemia and consecutive demise of the fetus. The infection of the fetus was without significant impact on its death. This rare complication of pregnancy can appear independently to the severity of COVID-19’s clinical course in the pregnant mother.

COVID-19 Vaccine Acceptance of Pregnant and Lactating Women (PLW) in Czechia: An Analytical Cross-Sectional Study

Pregnant and lactating women (PLW) represent a particular population subset with increased susceptibility for COVID-19 morbidity and mortality, even though the evidence about the safety and efficacy of COVID-19 vaccines was delayed due to their initial exclusion from development trials. This unclear situation could have led to increased COVID-19 vaccine hesitancy levels among PLW; therefore, this study aimed to evaluate the attitudes of Czech PLW towards COVID-19 vaccines and the determinants of their attitudes. An analytical cross-sectional survey-based study was carried out in the University Hospital Brno (South Moravia, Czechia) between August and October 2021. The study utilised a self-administered questionnaire (SAQ) adapted from previous instruments used for the same purpose. The SAQ included closed-ended items covering demographic characteristics, clinical and obstetric characteristics, attitudes towards COVID-19 vaccination, and potential psychosocial predictors of vaccine acceptance. Out of the 362 included participants, 278 were pregnant (PW) and 84 were lactating women (LW). The overall COVID-19 vaccine acceptance (immediate and delayed) level was substantially high (70.2%), with a significant difference between PW (76.6%) and LW (48.8%). Out of the 70.2% who agreed to receive the vaccine, 3.6% indicated immediate acceptance, and 66.6% indicated delayed acceptance. Only 13.3% of the participants indicated their acceptance of their physician's vaccination recommendation during pregnancy or while lactating, and 62.2% were against it. Our results agreed with the recent studies that revealed that PW tended to have a high level of COVID-19 vaccine acceptance, and they were also inclined to resist professional recommendations because they predominantly preferred to delay their vaccination. The pregnancy trimester, education level, employment status, and previous live births were significant determinants for COVID-19 vaccine acceptance. The most commonly preferred vaccine type was mRNA-based vaccines, followed by viral vector-based and inactivated virus vaccines. The first top priority of PLW was vaccine safety for their children, followed by vaccine safety for the PLW and vaccine effectiveness. Regarding psychosocial predictors, media/social media, trust in the government, the pharmaceutical industry, and healthcare professionals, partners, and a positive risk-benefit ratio were significant promoters for COVID-19 vaccine acceptance. Findings from this study suggest that promotional interventions targeting PLW should use web platforms and focus on vaccine safety evidence, the expected benefits of vaccines and potential harms of the infection.

Global research priorities on COVID-19 for maternal, newborn, child and adolescent health

BACKGROUND

This research prioritization aimed to identify major research gaps in maternal, newborn, child and adolescent health (MNCAH) to help mitigate the direct and indirect effects of the COVID-19 pandemic.

METHODS

We adapted the Child Health and Nutrition Research Initiative methodology. We defined scope, domains, themes and scoring criteria. We approached diverse global experts via email to submit their research ideas in MNCAH and MNCAH-related cross-cutting/health systems area. We curated the research ideas as research questions (RQs) and sent them to the consenting experts for scoring via the online link. For each RQ, the research priority score (RPS) was calculated as an average of individual criterion scores and ranked based on RPS in each area.

RESULTS

We identified top-ranked 10 RQs in each maternal, newborn, and child and adolescent health and 5 in the cross-cutting/health systems area. In maternal health, indirect effects on care, measures to improve care, health risks and outcomes, and preventing and managing SARS-CoV-2 infection/COVID-19 disease were priority RQs. In newborn health, clinical characterization and managing SARS-CoV-2 infection/COVID-19 disease, mode of transmission and interventions to prevent transmission were the focus. For child and adolescent health, top-ranked RQs were indirect effects on care, clinical status and outcomes, interventions to protect against SARS-CoV-2 infection/COVID-19 disease, and educational institute-related RQs. The cross-cutting RQs were the effects of the pandemic on availability, access, care-seeking and utilization of MNCAH services and potential solutions.

CONCLUSIONS

We call on partners, including governments, non-governmental organizations, research institutes, and donors, to address this urgent research agenda.

Pregnancy and COVID-19: prevention, vaccination, therapy, and beyond

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has alarmed the world since its first emergence. As pregnancy is characterized by significant changes in cardiovascular, respiratory, endocrine, and immunological systems, there are concerns on issues like the course of disease in pregnant women, safety of medications, route of delivery and risk of obstetric complications. The aim of this review is to summarize the current literature in the management of pregnant women during the COVID-19 pandemic. Although more than 90% of pregnant women with COVID-19 recover without serious morbidity, rapid deterioration of disease and higher rates of obstetric complications may be observed. The risk of vertical transmission has not been clearly revealed yet. Decreasing the number of prenatal visits, shortening the time allocated for the examinations, active use of telemedicine services, limiting the number of persons in healthcare settings, combining prenatal tests in the same visit, restricting visitors during the visits, providing a safe environment in healthcare facilities, strict hygiene control, and providing personal protective equipment during the visits are the main strategies to control the spread of disease according to current guidelines. Although new medication alternatives are being proposed every day for the treatment of COVID-19, our knowledge about the use of most of these drugs in pregnancy is limited. Preliminary results are promising for the administration of SARS-CoV-2 vaccines in the pregnant population. Timing of delivery should be decided based on maternal health condition, accompanying obstetric complications and gestational age. Cesarean delivery should be performed for obstetric indications. Breast feeding should be encouraged as long as necessary precautions for viral transmission are taken. In conclusion, an individualized approach should be provided by a multidisciplinary team for the management of pregnant women with COVID-19 to achieve favorable outcomes.

Evaluation of transplacental transfer of mRNA vaccine products and functional antibodies during pregnancy and early infancy

Studies are needed to evaluate the safety and effectiveness of mRNA SARS-CoV-2 vaccination during pregnancy, and the levels of protection provided to their newborns through placental transfer of antibodies. We evaluated the transplacental transfer of mRNA vaccine products and functional anti-SARS-CoV-2 antibodies during pregnancy and early infancy in a cohort of 20 individuals vaccinated during pregnancy. We found no evidence of mRNA vaccine products in maternal blood, placenta tissue, or cord blood at delivery. However, we found time-dependent efficient transfer of IgG and neutralizing antibodies to the neonate that persisted during early infancy. Additionally, using phage immunoprecipitation sequencing, we found a vaccine-specific signature of SARS-CoV-2 Spike protein epitope binding that is transplacentally transferred during pregnancy. In conclusion, products of mRNA vaccines are not transferred to the fetus during pregnancy, however timing of vaccination during pregnancy is critical to ensure transplacental transfer of protective antibodies during early infancy.

Evaluation of transplacental transfer of mRNA vaccine products and functional antibodies during pregnancy and early infancy

Studies are needed to evaluate the safety and effectiveness of mRNA SARS-CoV-2 vaccination during pregnancy, and the levels of protection provided to their newborns through placental transfer of antibodies. We evaluated the transplacental transfer of mRNA vaccine products and functional anti-SARS-CoV-2 antibodies during pregnancy and early infancy in a cohort of 20 individuals vaccinated during pregnancy. We found no evidence of mRNA vaccine products in maternal blood, placenta tissue, or cord blood at delivery. However, we found time-dependent efficient transfer of IgG and neutralizing antibodies to the neonate that persisted during early infancy. Additionally, using phage immunoprecipitation sequencing, we found a vaccine-specific signature of SARS-CoV-2 Spike protein epitope binding that is transplacentally transferred during pregnancy. In conclusion, products of mRNA vaccines are not transferred to the fetus during pregnancy, however timing of vaccination during pregnancy is critical to ensure transplacental transfer of protective antibodies during early infancy.

Placental Expression of ACE2 and TMPRSS2 in Maternal Severe Acute Respiratory Syndrome Coronavirus 2 Infection: Are Placental Defenses Mediated by Fetal Sex?

BACKGROUND

Expression of angiotensin-converting enzyme 2 (ACE2) and type II transmembrane serine protease (TMPRSS2), host molecules required for viral entry, may underlie sex differences in vulnerability to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We investigated whether placental ACE2 and TMPRSS2 expression vary by fetal sex in the presence of maternal SARS-CoV-2 infection.

METHODS

Placental ACE2 and TMPRSS2 expression was quantified by quantitative reverse transcription polymerase chain reaction (RT-PCR) and by Western blot in 68 pregnant women (38 SARS-CoV-2 positive, 30 SARS-CoV-2 negative) delivering at Mass General Brigham from April to June 2020. The impact of fetal sex and maternal SARS-CoV-2 exposure on ACE2 and TMPRSS2 was analyzed by 2-way analysis of variance (ANOVA).

RESULTS

Maternal SARS-CoV-2 infection impacted placental TMPRSS2 expression in a sexually dimorphic fashion (2-way ANOVA interaction, P = .002). We observed no impact of fetal sex or maternal SARS-CoV-2 status on ACE2. TMPRSS2 expression was significantly correlated with ACE2 expression in males (Spearman ρ = 0.54, P = .02) but not females (ρ = 0.23, P = .34) exposed to maternal SARS-CoV-2.

CONCLUSIONS

Sex differences in placental TMPRSS2 but not ACE2 were observed in the setting of maternal SARS-CoV-2 infection, which may have implications for offspring vulnerability to placental infection.

Is SARS-CoV-2 Infection a Risk Factor for Early Pregnancy Loss? ACE2 and TMPRSS2 Coexpression and Persistent Replicative Infection in Primitive Trophoblast

BACKGROUND

SARS-CoV-2 infection in term placenta is rare. However, growing evidence suggests that susceptibility of the human placenta to infection may vary by gestational age and pathogen. For several viral infections, susceptibility appears to be greatest during early gestation. Peri-implantation placental infections that result in pre-clinical pregnancy loss would typically go undetected. Little is known about the effects of SARS-CoV-2 on the peri-implantation human placenta since this time in pregnancy can only be modeled in vitro.

METHODS

We used a human embryonic stem cell (hESC)-derived model of peri-implantation placental development to assess patterns of ACE2 and TMPRSS2 transcription and protein expression in primitive trophoblast. We then infected the same trophoblast cell model with a clinical isolate of SARS-CoV-2 and documented infection dynamics.

RESULTS

ACE2 and TMPRSS2 were transcribed and translated in hESC-derived trophoblast, with preferential expression in syncytialized cells. These same cells supported replicative and persistent infection by SARS-CoV-2, while non-syncytialized trophoblast cells in the same cultures did not.

CONCLUSIONS

Co-expression of ACE2 and TMPRSS2 in hESC-derived trophoblast and the robust and replicative infection limited to syncytiotrophoblast equivalents support the hypothesis that increased viral susceptibility may be a defining characteristic of primitive trophoblast.

Comprehensive Serological Profile and Specificity of Maternal and Neonatal Cord Blood SARS CoV-2 Antibodies

OBJECTIVE

To describe the profile and specificity of maternal and neonatal cord-blood antibody profile in response SARS-CoV-2 virus exposure.

METHODS

This is a Prospective cohort study of delivering patients at Thomas Jefferson University Hospital from April 2020-February 2021. Primary objective was to describe unique maternal and fetal antibody epitope titers and specificity in those patients with COVID-19 history. Serologic profile assessed with a multiplex platform. Antigens used were: HA-trimer Influenza A (Hong Kong H3), spike trimers for SARS-CoV-2, SARS-CoV-1, MERS-CoV, and betacoronaviruses HKU-1 and OC43, as well as the spike N-terminal domain (NTD), spike receptor binding domain (RBD), and nucleocapsid protein (N; full length) for SARS-CoV-2.

RESULTS

112 maternal samples and 101 maternal and cord blood pairs were analyzed. Thirty-seven had a known history of COVID-19 (positive PCR test) in the pregnancy and of those, 17 (47%) were diagnosed with COVID-19 within 30 days of delivery. Fifteen of remaining seventy-six (20%) without a known diagnosis had positive maternal serology. For those with history of COVID-19 we identified robust IgG response in maternal blood to CoV2 nucleocapsid (N), spike (S) full-length and S (RBD) antigens with more modest responses to the S (NTD) antigen. By contrast, the maternal blood IgM response appeared more specific to S (full-length), than N, S (RBD) or S (NTD) epitopes. There were significantly higher maternal and cord blood IgG response not just to CoV2 spike (p < 10 ^-18 ), but also CoV1 spike (p < 10 ^-9 ) and MERS spike (p < 10 ^-8 ). By contrast, maternal IgM responses were more specific to CoV2 (p < 10 ^-19 ), but to a lesser degree for CoV1 (p < 10 ^-5 ), and no significant differences for MERS. Maternal and cord-blood IgG were highly correlated for both S and N (R ² = 0.96 and 0.94).

CONCLUSIONS

Placental transfer is efficient, with robust N and S responses. Both nucleocapsid and spike antibody responses should be studied for a better understanding of COVID-19 immunity. IgG antibodies are cross reactive with related CoV-1 and MERS spike epitopes while IgM, which cannot cross placenta to provide neonatal passive immunity, is more SARS CoV-2 specific. Neonatal cord blood may have significantly different fine-specificity than maternal blood, despite the high efficiency of IgG transfer.

Ratio of asymptomatic COVID-19 cases among ascertained SARS-CoV-2 infections in different regions and population groups in 2020: a systematic review and meta-analysis including 130 123 infections from 241 studies

INTRODUCTION

Asymptomatic infection of SARS-CoV-2 may lead to silent community transmission and compromise the COVID-19 pandemic control measures. We aimed to estimate the rate of asymptomatic COVID-19 from published studies and compare this rate among different regions and patient groups.

METHODS

In this systematic review and meta-analysis, electronic databases including Medline, Embase, PubMed and three Chinese electronic databases (Chinese National Knowledge Infrastructure [CNKI], WanFang Data and China Science, and Technology Journal Database [VIP]) were searched for literature published from 1 November 2019 to 31 December 2020. Original investigations with sample size (or number of subjects) not less than five were included for further analyses. Subgroup analyses were conducted according to different study types, study periods, geographical regions and patient demographics. The STATA (V.14.0) command 'metaprop' was implemented to conduct a meta-analysis of the pooled rate estimates of asymptomatic infections with exact binomial and score test-based 95% confidence interval (CI).

RESULTS

A total of 130 123 ascertained COVID-19 infections from 241 studies were included in this meta-analysis, including 31 411 asymptomatic infections. The overall rate of asymptomatic infections was 23.6% (18.5%-29.1%) and 21.7% (16.8%-27.0%) before and after excluding presymptomatic cases, respectively. Subgroup analysis showed that significantly higher in pregnant women (48.8%, 28.9%-68.9%), children (32.1%, 24.2%-40.5%), and studies reporting screening programmes (36.0%, 24.6%-48.1%) conducted on or after 1 March 2020 (42.5%, 33.4%-51.9%). In terms of geographical region, the rate was the highest in Africa (64.3%, 56.7%-71.6%), followed by America (40.0%, 27.4%-53.3%), Europe (28.1%, 19.0%-38.1%) and Asia (18.1%, 13.2%-23.5%).

CONCLUSION

We approximated that one-fifth of COVID-19 infections are asymptomatic throughout the course of infection. Public health policies targeting these high-risk groups may be recommended to achieve early identification and more stringent containment of the pandemic.

Maternal-fetal immunologic response to SARS-CoV-2 infection in a symptomatic vulnerable population: A prospective cohort

BACKGROUND

COVID-19 disproportionally affects pregnant women and their newborn, yet little is known about the variables that modulate the maternal-fetal immune response to infection.

METHODS

We prospectively studied socioeconomic, biologic and clinical factors affecting humoral immunity in 87 unvaccinated pregnant women admitted to hospital in the Buenos Aires metropolitan area for symptoms consistent with COVID-19 disease.

RESULTS

The number of days between symptom onset and childbirth predicted maternal and newborn virus Spike protein Receptor Binding Domain (RBD)-specific IgG. These findings suggest newborns may benefit less when mothers deliver soon after COVID-19 infection. Similarly, a longer time between symptom onset and birth predicted higher in utero transfer of maternal IgG and its concentration in cord blood. Older gestational ages at birth were associated with lower maternal IgG: cord blood IgG ratios. Eighty seven percent of women with confirmed SARS-CoV-2 infection developed RBD-specific IgA responses in breast milk within 96 h of childbirth. IgA was not significantly associated with time from infection but correlated with maternal serum IgG and placental transfer.

CONCLUSIONS

These results demonstrate the combined role of biologic, clinical and socioeconomic variables associated with maternal SARS-CoV-2 RBD-specific antibodies and supports early vaccination strategies for COVID-19 in socioeconomically vulnerable pregnant women.

Comprehensive Serological Profile and Specificity of Maternal and Neonatal Cord Blood SARS CoV-2 Antibodies

BACKGROUND

Initial studies on COVID-19 in pregnancy have demonstrated a range of neutralizing activity, but little has been published on the full profile of SARS CoV-2 related antibodies in maternal and cordblood.

OBJECTIVE

This study aimed to describe the profile and specificity of maternal and neonatal cord blood antibody profiles in response to SARS-CoV-2 virus exposure.

STUDY DESIGN

This was a prospective cohort study of delivering patients at Thomas Jefferson University Hospital from April 2020 to February 2021. The primary objective was to describe unique maternal and fetal antibody epitope titers and specificity in patients with COVID-19 history. Serologic profile was assessed with a multiplex platform. Antigens used were hemagglutinin trimer influenza A (Hong Kong H3); spike trimers for SARS-CoV-2, SARS-CoV-1, Middle East respiratory syndrome coronavirus, and betacoronaviruses HKU-1 and OC43; and spike N-terminal domain, spike receptor-binding domain, and nucleocapsid protein (full length) for SARS-CoV-2.

RESULTS

Here, 112 maternal samples and 101 maternal and cord blood pairs were analyzed. Of note, 37 patients had a known history of COVID-19 (positive polymerase chain reaction test) during pregnancy. Of 36 patients, 16 (44%) were diagnosed with COVID-19 within 7 days of delivery. Moreover, 15 of the remaining 76 patients (20%) without a known diagnosis had positive maternal serology. For those with a history of COVID-19, we identified robust immunoglobulin G response in maternal blood to CoV-2 nucleocapsid, spike (full length), and spike (receptor-binding domain) antigens with more modest responses to the spike (N-terminal domain) antigen. In contrast, the maternal blood immunoglobulin M response seemed more specific to spike (full length) epitopes than nucleocapsid, spike (receptor-binding domain), or spike (N-terminal domain) epitopes. There were significantly higher maternal and cord blood immunoglobulin G responses not only to CoV-2 spike (127.1-fold; standard deviation, 2.0; P<.00001) but also to CoV-1 spike (21.1-fold higher; standard deviation, 1.8; P<.00001) and Middle East respiratory syndrome spike (6.9-fold higher; standard deviation, 2.5; P<.00001). In contrast, maternal immunoglobulin M responses were more specific to CoV-2 spike (15.8-fold; standard deviation, 2.1; P<.00001) but less specific to CoV-1 (2.5-fold higher; standard deviation, 0.71; P<.00001) and no significant difference for Middle East respiratory syndrome. Maternal and cord blood immunoglobulin G antibodies were highly correlated for both spike and nucleocapsid (R²=0.96 and 0.94, respectively).

CONCLUSION

Placental transfer was efficient, with robust nucleocapsid and spike responses. Both nucleocapsid and spike antibody responses should be studied for a better understanding of COVID-19 immunity. Immunoglobulin G antibodies were cross-reactive with related CoV-1 and Middle East respiratory syndrome spike epitopes, whereas immunoglobulin M antibodies, which cannot cross the placenta to provide neonatal passive immunity, were more SARS-CoV-2 specific. Neonatal cord blood may have significantly different fine specificity than maternal blood, despite the high efficiency of immunoglobulin G transfer.

A standardized definition of placental infection by SARS-CoV-2, a consensus statement from the National Institutes of Health/Eunice Kennedy Shriver National Institute of Child Health and Human Development SARS-CoV-2 Placental Infection Workshop

Pregnant individuals infected with SARS-CoV-2 have higher rates of intensive care unit admission, oxygen requirement, need for mechanical ventilation, and death than nonpregnant individuals. Increased COVID-19 disease severity may be associated with an increased risk of viremia and placental infection. Maternal SARS-CoV-2 infection is also associated with pregnancy complications such as preeclampsia and preterm birth, which can be either placentally mediated or reflected in the placenta. Maternal viremia followed by placental infection may lead to maternal-fetal transmission (vertical), which affects 1% to 3% of exposed newborns. However, there is no agreed-upon or standard definition of placental infection. The National Institutes of Health/Eunice Kennedy Shriver National Institute of Child Health and Human Development convened a group of experts to propose a working definition of placental infection to inform ongoing studies of SARS-CoV-2 during pregnancy. Experts recommended that placental infection be defined using techniques that allow virus detection and localization in placental tissue by one or more of the following methods: in situ hybridization with antisense probe (detects replication) or a sense probe (detects viral messenger RNA) or immunohistochemistry to detect viral nucleocapsid or spike proteins. If the abovementioned methods are not possible, reverse transcription polymerase chain reaction detection or quantification of viral RNA in placental homogenates, or electron microscopy are alternative approaches. A graded classification for the likelihood of placental infection as definitive, probable, possible, and unlikely was proposed. Manuscripts reporting placental infection should describe the sampling method (location and number of samples collected), method of preservation of tissue, and detection technique. Recommendations were made for the handling of the placenta, examination, and sampling and the use of validated reagents and sample protocols (included as appendices).

Trends in SARS-CoV-2 seroprevalence amongst urban paediatric patients compared with a nationwide cohort in the Netherlands

Objectives

The extent of SARS-CoV-2 infection amongst children and their role in transmission remains unclear. Therefore, we aimed to estimate the SARS-CoV-2 antibody seroprevalence amongst children who presented to our hospital for non-COVID-19-related morbidity during the first and second epidemic wave in 2020 and compared these to the general Dutch paediatric population.

Methods

We collected residual plasma samples from all paediatric patients (1 month-17 years of age) visiting our clinic or emergency room, who had blood drawing for various medical reasons. Samples were analysed for the presence of total antibodies against SARS-CoV-2 by Wantai ELISA. The seroprevalence in two separate periods (July-Sep 2020, and Oct-Dec 2020) was compared to regional and national data (PIENTER-Corona study, September 2020), and associations with co-morbidities were assessed.

Results

A total of 209 samples in period 1 and 240 samples in period 2 were collected (median age 7.1 years, IQR 1.5–13.5). SARS-CoV-2 antibodies were detected in 4.1% and 13.8%, respectively (p< 0.001). Seroprevalence was higher compared to national paediatric data, but did not differ with regional estimates. Most children with SARS-CoV-2 antibodies were seen in the outpatient clinic for general paediatric problems with no differences in medical reasons for presentation between the two periods.

Conclusions

These data confirm a rapid three-fold increase in SARS-CoV-2 seroprevalence in paediatric patients in the second half of 2020 with a trend towards a higher seroprevalence compared to randomly-selected children in a nationwide study. Underlying morbidity in children might not play an important role in acquiring SARS-CoV-2 infection.

Society for Maternal-Fetal Medicine Special Statement: COVID-19 research in pregnancy: progress and potential

The COVID-19 global pandemic has broad implications for obstetrical care and perinatal outcomes. As we approach the 2-year mark into an unprecedented international pandemic, this review presents the progress and opportunities for research related to COVID-19 and pregnancy. Research is the basis for evidence-based clinical guidelines, and we aim to provide the structure and guidance for framing COVID-19-related obstetrical research. This structure will pertain not only to this pandemic but future ones as well.

The legacy of maternal SARS-CoV-2 infection on the immunology of the neonate

Despite extensive studies into severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the effect of maternal infection on the neonate is unclear. To investigate this, we characterized the immunology of neonates born to mothers with confirmed SARS-CoV-2 infection during pregnancy. Here we show that maternal SARS-CoV-2 infection affects the neonatal immune system. Despite similar proportions of B cells, CD4⁺ T cells and CD8⁺ T cells, increased percentages of natural killer cells, Vδ2⁺ γδ T cells and regulatory T cells were detected in neonates born to mothers with recent or ongoing infection compared with those born to recovered or uninfected mothers. Increased plasma cytokine levels were also evident in neonates and mothers within the recent or ongoing infection group. Cytokine functionality was enhanced in neonates born to SARS-CoV-2-exposed mothers, compared to those born to uninfected mothers. In most neonates, this immune imprinting was nonspecific, suggesting vertical transmission of SARS-CoV-2 is limited, a finding supported by a lack of SARS-CoV-2-specific IgM in neonates despite maternal IgG transfer.

[Vaccine against COVID-19]

The COVID-19 pandemic has produced a huge health, economic and psychological collapse in our society. Health workers have had to face one of the greatest challenges in history, trying to show the population how to deal with this disease. We have learned that vaccines are the great instrument for the fight against infectious diseases and a large number of them began to appear, not as a product of chance but as a product of the enormous progress experienced in recent years with vaccines against new infectious diseases, against other diseases such as Alzheimer's and especially against cancer. All this knowledge has been applied to this disease. Practitioners lamented the little information available to them when asked questions from patients. This document wanted to be a response to these concerns, with a scientific desire, with evidence that put aside unverified data and hoaxes. Faced with an avalanche of information, most of it without the appropriate "peer review" as indicated in the introduction, any publication becomes obsolete at the time of publication, and we opted for an "online" publication, with the incorporation of versions. This online publication has been published in the documents of Spanish Society of Chemotherapy, at https://seq.es/vacunacion-covid-19.

The Impact of the Coronavirus Disease 19 Pandemic on Early Pregnancy Outcomes Among Patients Undergoing In Vitro Fertilization Treatment

Objective: To determine if pregnancy rates (PRs) or pregnancy loss rates (PLRs) were altered in patients undergoing single, euploid frozen-thawed embryo transfer (FET) during the initial peak of the Coronavirus Disease 19 (COVID-19) pandemic.

Materials and Methods: This was a retrospective cohort study performed in a single academic center. Patients undergoing single, euploid FET cycles from January to May 2017–2020 were included. Cycles with FET performed in January–May of 2020 (“COVID-surge cohort”) were compared to cycles with FET performed in January–May of 2017–2019 (“pre-COVID cohort”). Pregnancy rate (PR), clinical pregnancy rate (CPR), pregnancy loss rate (PLR), and clinical pregnancy loss rate (CLR) were compared between the cohorts.

Results: A total of 2629 single, euploid FET cycles were included: 2070 from January to May, 2017–2019 and 559 from January to May 2020. PR was similar when comparing FET performed from January to May 2020 (COVID-surge) to those performed from January to May, 2017–2019 (pre-COVID) (77.6% vs. 73.7%, p = 0.06), while CPR was higher among the COVID-surge compared to the pre-COVID cohort (65.5% vs. 60.0%, p = 0.02). No differences were seen in PLR and CLR among the COVID-surge and pre-COVID cohorts (28.3% vs. 32.0%, p = 0.08; 15.0% vs. 16.5%, p = 0.50). PR, CPR, PLR, and CLR were similar when comparing individual months between the cohorts. Adjusted analysis showed no differences in PR, CPR, PLR, or CLR when comparing the cohorts overall or when comparing corresponding individual months in the two time periods.

Conclusion: PRs and PLRs were not decreased when SARS-CoV-2 transmission was widespread in our geographic area, suggesting that high COVID-19 transmission does not compromise early pregnancy outcomes.

Developmental Aspects of SARS-CoV-2, Potential Role of Exosomes and Their Impact on the Human Transcriptome

With over 4.8 million deaths within 2 years, time is of the essence in combating COVID-19. The infection now shows devastating impacts on the younger population, who were not previously predicted to be vulnerable, such as in the older population. COVID-19-related complications have been reported in neonates whose mothers were infected with SARS-CoV-2 during pregnancy, and in children who get infected. Hence, a deeper understanding of the pathophysiology of COVID-19 during various developmental stages and placental transmission is essential. Although a connection has not yet been established between exosomal trafficking and the placental transmission of COVID-19, reports indicate that SARS-CoV-2 components may be trafficked between cells through exosomes. As the infection spreads, the transcriptome of cells is drastically perturbed, e.g., through the severe upregulation of several immune-related genes. Consequently, a major outcome of COVID-19 is an elevated immune response and the detection of viral RNA transcripts in host tissue. In this direction, this review focuses on SARS-CoV-2 virology, its in utero transmission from infected pregnant mothers to fetuses, SARS-CoV-2 and exosomal cellular trafficking, transcriptomic impacts, and RNA-mediated therapeutics against COVID-19. Future research will establish stronger connections between the above processes to develop diagnostic and therapeutic solutions towards COVID-19 and similar viral outbreaks.

Frequent Placental SARS-CoV-2 in Patients with COVID-19-Associated Hypertensive Disorders of Pregnancy

Introduction

Studies described an increased frequency of hypertensive disorders of pregnancy (HDP) after a COVID-19 episode. There is limited evidence about SARS-CoV-2 viral load in placenta. This study aimed to investigate the relationship between SARS-CoV-2 viral load in the placenta and clinical development of HDP after COVID-19 throughout different periods of gestation.

Methods

This is a case-control study in women with and without gestational hypertensive disorders after SARS-CoV-2 infection diagnosed by RT-PCR during pregnancy. Patients were matched by gestational age at the moment of COVID-19 diagnosis. We performed an analysis of SARS-CoV-2 RNA levels in placenta.

Results

A total of 28 women were enrolled. Sixteen patients were diagnosed with COVID-19 during the third trimester and the remaining 12 patients in the other trimesters. Ten placentas (35.7%) were positive for SARS-CoV-2, 9 of them (9/14, 64.3%) belonged to the HDP group versus 1 (1/14, 7.2%) in the control group (p = 0.009). Those cases with the highest loads of viral RNA developed severe preeclampsia (PE).

Conclusion

Among women diagnosed with COVID-19 during pregnancy, the presence of SARS-CoV-2 in the placenta was more frequent among women suffering from PE or gestational hypertension. Furthermore, the most severe cases of HDP were associated with high placental viral load, not necessarily associated with a positive nasopharyngeal RT-PCR at delivery. Our data suggest that SARS-CoV-2 infection during pregnancy could trigger gestational hypertensive disorders through persistent placental infection and resulting placental damage.