Responses to a Neutralizing Monoclonal Antibody for Hospitalized Patients With COVID-19 According to Baseline Antibody and Antigen Levels : A Randomized Controlled Trial.

BACKGROUND: In a randomized, placebo-controlled, clinical trial, bamlanivimab, a SARS-CoV-2-neutralizing monoclonal antibody, given in combination with remdesivir, did not improve outcomes among hospitalized patients with COVID-19 based on an early futility assessment. OBJECTIVE: To evaluate the a priori hypothesis that bamlanivimab has greater benefit in patients without detectable levels of endogenous neutralizing antibody (nAb) at study entry than in those with antibodies, especially if viral levels are high. DESIGN: Randomized, placebo-controlled trial. (ClinicalTrials.gov: NCT04501978). SETTING: Multicenter trial. PATIENTS: Hospitalized patients with COVID-19 without end-organ failure. INTERVENTION: Bamlanivimab (7000 mg) or placebo. MEASUREMENTS: Antibody, antigen, and viral RNA levels were centrally measured on stored specimens collected at baseline. Patients were followed for 90 days for sustained recovery (defined as discharge to home and remaining home for 14 consecutive days) and a composite safety outcome (death, serious adverse events, organ failure, or serious infections). RESULTS: Among 314 participants (163 receiving bamlanivimab and 151 placebo), the median time to sustained recovery was 19 days and did not differ between the bamlanivimab and placebo groups (subhazard ratio [sHR], 0.99 [95% CI, 0.79 to 1.22]; sHR > 1 favors bamlanivimab). At entry, 50% evidenced production of anti-spike nAbs; 50% had SARS-CoV-2 nucleocapsid plasma antigen levels of at least 1000 ng/L. Among those without and with nAbs at study entry, the sHRs were 1.24 (CI, 0.90 to 1.70) and 0.74 (CI, 0.54 to 1.00), respectively (nominal P for interaction = 0.018). The sHR (bamlanivimab vs. placebo) was also more than 1 for those with plasma antigen or nasal viral RNA levels above median level at entry and was greatest for those without antibodies and with elevated levels of antigen (sHR, 1.48 [CI, 0.99 to 2.23]) or viral RNA (sHR, 1.89 [CI, 1.23 to 2.91]). Hazard ratios for the composite safety outcome (<1 favors bamlanivimab) also differed by serostatus at entry: 0.67 (CI, 0.37 to 1.20) for those without and 1.79 (CI, 0.92 to 3.48) for those with nAbs. LIMITATION: Subgroup analysis of a trial prematurely stopped because of futility; small sample size; multiple subgroups analyzed. CONCLUSION: Efficacy and safety of bamlanivimab may differ depending on whether an endogenous nAb response has been mounted. The limited sample size of the study does not allow firm conclusions based on these findings, and further independent trials are required that assess other types of passive immune therapies in the same patient setting. PRIMARY FUNDING SOURCE: U.S. government Operation Warp Speed and National Institute of Allergy and Infectious Diseases.

An outbreak of SARS-CoV-2 with high mortality in mink (Neovison vison) on multiple Utah farms.

The breadth of animal hosts that are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and may serve as reservoirs for continued viral transmission are not known entirely. In August 2020, an outbreak of SARS-CoV-2 occurred on five mink farms in Utah and was associated with high mink mortality (35-55% of adult mink) and rapid viral transmission between animals. The premise and clinical disease information, pathology, molecular characterization, and tissue distribution of virus within infected mink during the early phase of the outbreak are provided. Infection spread rapidly between independently housed animals and farms, and caused severe respiratory disease and death. Disease indicators were most notably sudden death, anorexia, and increased respiratory effort. Gross pathology examination revealed severe pulmonary congestion and edema. Microscopically there was pulmonary edema with moderate vasculitis, perivasculitis, and fibrinous interstitial pneumonia. Reverse transcriptase polymerase chain reaction (RT-PCR) of tissues collected at necropsy demonstrated the presence of SARS-CoV-2 viral RNA in multiple organs including nasal turbinates, lung, tracheobronchial lymph node, epithelial surfaces, and others. Localization of viral RNA by in situ hybridization revealed a more localized infection, particularly of the upper respiratory tract. Whole genome sequencing from multiple mink was consistent with published SARS-CoV-2 genomes with few polymorphisms. The Utah mink SARS-CoV-2 strains fell into Clade GH, which is unique among mink and other animal strains sequenced to date. While sharing the N501T mutation which is common in mink, the Utah strains did not share other spike RBD mutations Y453F and F486L found in nearly all mink from the United States. Mink in the outbreak reported herein had high levels of SARS-CoV-2 in the upper respiratory tract associated with symptomatic respiratory disease and death.

Brief Report: Impact of the COVID-19 Pandemic on Virological Suppression in People Living With HIV Attending a Large Italian HIV Clinic.

BACKGROUND: We assessed the impact of the coronavirus disease 2019 (COVID-19) pandemic on HIV suppression rates in people living with HIV (PLWH) attending a large Italian HIV clinic. SETTING: The HIV outpatient clinic of the Infectious Diseases Department of Luigi Sacco Hospital, Milan, Italy, which serves more than 5000 PLWH per year. METHODS: A before and after quasi-experimental study design was used to make a retrospective assessment of the monthly trend of HIV-RNA determinations of ≥50 among the PLWH attending our clinic, with "before" being the period from January 1, 2016 to February 20, 2020, and "after" being the period from February 21, 2020 to December 31, 2020 (the COVID-19 period). Interrupted time series analysis was used to evaluate any changes in the trend. RESULTS: During the study period, 70,349 HIV-RNA viral load determinations were made, and the percentage of HIV-RNA viral load determinations of <50 copies/mL increased from 88.4% in 2016 to 93.2% in 2020 (P < 0.0001). There was a significant monthly trend toward a decrease in the number of HIV-RNA determinations of ≥50 copies/mL before the pandemic (ß -0.084; standard error 0.015; P < 0.001), and this did not significantly change after it started (ß -0.039, standard error 0.161; P = 0.811). CONCLUSIONS: A high prevalence of viral suppression was maintained among the PLWH referring to our clinic, despite the structural barriers raised by the COVID-19 pandemic. The use of simplified methods of delivering care (such as teleconsultations and multiple antiretroviral treatment prescriptions) may have contributed to preserving this continuum.

Sequential dynamics of virological and serological changes in the serum of SARS-CoV-2 infected patients.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load dynamics in respiratory samples have been studied, but knowledge about changes in serial serum samples of infected patients in relation to their immunological response is lacking. We investigated the dynamics of SARS-CoV-2 viral load and antibody response in sequential serum of coronavirus disease 2019 (COVID-19) patients and attempted to culture the virus in the serum. A total of 81 sequential serum samples from 10 confirmed COVID-19 patients (5 with mild and 5 with moderate symptoms) were analyzed. Samples were collected during hospitalization and after discharge (median follow-up of 35 days). SARS-CoV-2 ribonucleic acid in the serum was detected by real-time polymerase chain reaction. Total antibody and IgG to SARS-CoV-2 Spike protein were analyzed by Chemiluminescent Immunoassays, and neutralizing antibodies were detected using a Surrogate Virus Neutralization Test. Viremia was observed in all cases at admission, and viral copy gradually dropped to undetectable levels in patients with mild symptoms but fluctuated and remained persistent in moderate cases. The viral culture of samples with the highest viral load for each patient did not show any cytopathic change. The antibody response was faster and higher in moderate cases. This study provides a basic clue for infectious severity-dependent immune response, viremia, and antibody acquisition pattern.

Coinfection between SARS-CoV-2 and vector-borne diseases in Luanda, Angola.

Co-epidemics happening simultaneously can generate a burden on healthcare systems. The co-occurrence of SARS-CoV-2 with vector-borne diseases (VBD), such as malaria and dengue in resource-limited settings represents an additional challenge to the healthcare systems. Herein, we assessed the coinfection rate between SARS-CoV-2 and VBD to highlight the need to carry out an accurate diagnosis and promote timely measures for these infections in Luanda, the capital city of Angola. This was a cross-sectional study conducted with 105 subjects tested for the SARS-CoV-2 and VBD with a rapid detection test in April 2021. The participants tested positive for SARS-CoV-2 (3.80%), malaria (13.3%), and dengue (27.6%). Low odds related to testing positivity to SARS-CoV-2 or VBD were observed in participants above or equal to 40 years (odds ratio [OR]: 0.60, p = 0.536), while higher odds were observed in male (OR: 1.44, p = 0.392) and urbanized areas (OR: 3.78, p = 0.223). The overall co-infection rate between SARS-CoV-2 and VBD was 11.4%. Our findings showed a coinfection between SARS-CoV-2 with malaria and dengue, which could indicate the need to integrate the screening for VBD in the SARS-CoV-2 testing algorithm and the adjustment of treatment protocols. Further studies are warranted to better elucidate the relationship between COVID-19 and VBD in Angola.

Low anti-SARS-CoV-2 S antibody levels predict increased mortality and dissemination of viral components in the blood of critical COVID-19 patients.

BACKGROUND: Anti-SARS-CoV-2 S antibodies prevent viral replication. Critically ill COVID-19 patients show viral material in plasma, associated with a dysregulated host response. If these antibodies influence survival and viral dissemination in ICU-COVID patients is unknown. PATIENTS/METHODS: We studied the impact of anti-SARS-CoV-2 S antibodies levels on survival, viral RNA-load in plasma, and N-antigenaemia in 92 COVID-19 patients over ICU admission. RESULTS: Frequency of N-antigenaemia was >2.5-fold higher in absence of antibodies. Antibodies correlated inversely with viral RNA-load in plasma, representing a protective factor against mortality (adjusted HR [CI 95%], p): (S IgM [AUC ≥ 60]: 0.44 [0.22; 0.88], 0.020); (S IgG [AUC ≥ 237]: 0.31 [0.16; 0.61], <0.001). Viral RNA-load in plasma and N-antigenaemia predicted increased mortality: (N1-viral load [≥2.156 copies/ml]: 2.25 [1.16; 4.36], 0.016); (N-antigenaemia: 2.45 [1.27; 4.69], 0.007). CONCLUSIONS: Low anti-SARS-CoV-2 S antibody levels predict mortality in critical COVID-19. Our findings support that these antibodies contribute to prevent systemic dissemination of SARS-CoV-2.

Use of Outpatient-Derived COVID-19 Convalescent Plasma in COVID-19 Patients Before Seroconversion.

Background: Transfusion of COVID-19 convalescent plasma (CCP) containing high titers of anti-SARS-CoV-2 antibodies serves as therapy for COVID-19 patients. Transfusions early during disease course was found to be beneficial. Lessons from the SARS-CoV-2 pandemic could inform early responses to future pandemics and may continue to be relevant in lower resource settings. We sought to identify factors correlating to high antibody titers in convalescent plasma donors and understand the magnitude and pharmacokinetic time course of both transfused antibody titers and the endogenous antibody titers in transfused recipients. Methods: Plasma samples were collected up to 174 days after convalescence from 93 CCP donors with mild disease, and from 16 COVID-19 patients before and after transfusion. Using ELISA, anti-SARS-CoV-2 Spike RBD, S1, and N-protein antibodies, as well as capacity of antibodies to block ACE2 from binding to RBD was measured in an in vitro assay. As an estimate for viral load, viral RNA and N-protein plasma levels were assessed in COVID-19 patients. Results: Anti-SARS-CoV-2 antibody levels and RBD-ACE2 blocking capacity were highest within the first 60 days after symptom resolution and markedly decreased after 120 days. Highest antibody titers were found in CCP donors that experienced fever. Effect of transfused CCP was detectable in COVID-19 patients who received high-titer CCP and had not seroconverted at the time of transfusion. Decrease in viral RNA was seen in two of these patients. Conclusion: Our results suggest that high titer CCP should be collected within 60 days after recovery from donors with past fever. The much lower titers conferred by transfused antibodies compared to endogenous production in the patient underscore the importance of providing CCP prior to endogenous seroconversion.

Changes in peripheral blood in SARS CoV-2 patients and its clinico-pathological correlation: A prospective cross-sectional study.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) caused by SARS-CoV2 can present from mild flu-like symptoms to acute respiratory distress syndrome. There is multi-organ involvement; particularly, hematopoietic system can be associated with morphological changes in blood cells of COVID-19 patients. METHOD: We conducted a cross-sectional study on a cohort of 50 COVID-19 patients, confirmed on RT-PCR with documented cycle threshold (Ct) value. Peripheral blood sample of these patients was collected and examined for complete blood counts (CBC) on automated haematological analyser as well as Leishman-stained blood smears to look for morphological changes in blood cells. Morphological changes were evaluated with reference to clinical severity and Ct value. Additionally, association between Ct value and clinical severity was also performed. Statistical tests were performed, and P value <.05 was considered significant. RESULTS: Mean age of our study group was 42.16 ± 15.55 years, with male preponderance. Most commonly observed peripheral blood changes were hypolobation (P value = .002) and toxic granules (P value = .005) in neutrophils, atypical granules with nucleolar prominence in lymphocytes, cytoplasmic granulation with clumped nuclear chromatin in monocytes, giant platelets and thrombocytopenia and normocytic normochromic anaemia. CONCLUSION: No association was found between clinical severity and Ct value as well as peripheral blood morphological changes with Ct value. We conclude that examination of peripheral smear coupled with complete blood count (CBC) is only partially supportive of disease pathogenesis and to assess the viral load other parameters should be utilised instead of relying solely on Ct value.

Tracheostomy for COVID-19: evolving best practice.

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2021. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2021 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901 .

Daily monitoring of viral load measured as SARS-CoV-2 antigen and RNA in blood, IL-6, CRP and complement C3d predicts outcome in patients hospitalized with COVID-19.

OBJECTIVES: We hypothesized that the amount of antigen produced in the body during a COVID-19 infection might differ between patients, and that maximum concentrations would predict the degree of both inflammation and outcome for patients. METHODS: Eighty-four hospitalized and SARS-CoV-2 PCR swab-positive patients, were followed with blood sampling every day until discharge or death. A total of 444 serial EDTA plasma samples were analyzed for a range of biomarkers: SARS-CoV-2 nuclear antigen and RNA concentration, complement activation as well as several inflammatory markers, and KL-6 as a lung marker. The patients were divided into outcome groups depending on need of respiratory support and death/survival. RESULTS: Circulating SARS-CoV-2 nuclear antigen levels were above the detection limit in blood in 65 out of 84 COVID-19 PCR swab-positive patients on day one of hospitalization, as was viral RNA in plasma in 30 out of 84. In all patients, complete antigen clearance was observed within 24 days. There were definite statistically significant differences between the groups depending on their biomarkers, showing that the concentrations of virus RNA and antigen were correlated to the inflammatory biomarker levels, respiratory treatment and death. CONCLUSIONS: Viral antigen is cleared in parallel with the virus RNA levels. The levels of antigens and SARS-CoV-2 RNA in the blood correlates with the level of IL-6, inflammation, respiratory failure and death. We propose that the antigens levels together with RNA in blood can be used to predict the severity of disease, outcome, and the clearance of the virus from the body.

SARS-CoV-2 N-antigenemia in critically ill adult COVID-19 patients: Frequency and association with inflammatory and tissue-damage biomarkers.

The current study aimed at characterizing the dynamics of SARS-CoV-2 nucleocapsid (N) antigenemia in a cohort of critically ill adult COVID-19 patients and assessing its potential association with plasma levels of biomarkers of clinical severity and mortality. Seventy-three consecutive critically ill COVID-19 patients (median age, 65 years) were recruited. Serial plasma (n = 340) specimens were collected. A lateral flow immunochromatography assay and reverse-transcription polymerase chain reaction (RT-PCR) were used for SARS-CoV-2 N protein detection and RNA quantitation and in plasma, respectively. Serum levels of inflammatory and tissue-damage biomarkers in paired specimens were measured. SARS-CoV-RNA N-antigenemia and viral RNAemia were documented in 40.1% and 35.6% of patients, respectively at a median of 9 days since symptoms onset. The level of agreement between the qualitative results returned by the N-antigenemia assay and plasma RT-PCR was moderate (k = 0.57; p < 0.0001). A trend towards higher SARS-CoV-2 RNA loads was seen in plasma specimens testing positive for N-antigenemia assay than in those yielding negative results (p = 0.083). SARS-CoV-2 RNA load in tracheal aspirates was significantly higher (p < 0.001) in the presence of concomitant N-antigenemia than in its absence. Significantly higher serum levels of ferritin, lactose dehydrogenase, C-reactive protein, and D-dimer were quantified in paired plasma SARS-CoV-2 N-positive specimens than in those testing negative. Occurrence of SARS-CoV-2 N-antigenemia was not associated with increased mortality in univariate logistic regression analysis (odds ratio, 1.29; 95% confidence interval, 0.49-3.34; p = 0.59). In conclusion, SARS-CoV-2 N-antigenemia detection is relatively common in ICU patients and appears to associate with increased serum levels of inflammation and tissue-damage markers. Whether this virological parameter may behave as a biomarker of poor clinical outcome awaits further investigations.

SARS-CoV-2 RNAemia with a higher nasopharyngeal viral load is strongly associated with disease severity and mortality in patients with COVID-19.

This study aimed to determine the frequency of SARS-CoV-2 RNA in serum and its association with the clinical severity of COVID-19. This retrospective cohort study performed at Toyama University Hospital included consecutive patients with confirmed COVID-19. The prevalence of SARS-CoV-2 RNAemia and the strength of its association with clinical severity variables were examined. Fifty-six patients were included in this study. RNAemia was detected in 19.6% (11/56) patients on admission, and subsequently in 1.0% (1/25), 50.0% (6/12), and 100.0% (4/4) moderate, severe, and critically ill patients, respectively. Patients with RNAemia required more frequent oxygen supplementation (90.0% vs. 13.3%), ICU admission (81.8% vs. 6.7%), and invasive mechanical ventilation (27.3% vs. 0.0%). Among patients with RNAemia, the median viral loads of nasopharyngeal (NP) swabs that were collected around the same time as the serum sample were significantly higher in critically ill (5.4 log10 copies/µl; interquartile range [IQR]: 4.2-6.3) than in moderate-severe cases (2.6 log10 copies/µl; [IQR: 1.1-4.5]; p = 0.030) and were significantly higher in nonsurvivors (6.2 log10 copies/µl [IQR: 6.0-6.5]) than in survivors (3.9 log10 copies/µl [IQR: 1.6-4.6]; p = 0.045). This study demonstrated a relatively high proportion of SARS-CoV-2 RNAemia and an association between RNAemia and clinical severity. Moreover, among the patients with RNAemia, the viral loads of NP swabs were correlated with disease severity and mortality, suggesting the potential utility of combining serum testing with NP tests as a prognostic indicator for COVID-19, with higher quality than each separate test.

Detection of SARS-CoV-2 Derived Small RNAs and Changes in Circulating Small RNAs Associated with COVID-19.

Cleavage of double-stranded RNA is described as an evolutionary conserved host defense mechanism against viral infection. Small RNAs are the product and triggers of post transcriptional gene silencing events. Up until now, the relevance of this mechanism for SARS-CoV-2-directed immune responses remains elusive. Herein, we used high throughput sequencing to profile the plasma of active and convalescent COVID-19 patients for the presence of small circulating RNAs. The existence of SARS-CoV-2 derived small RNAs in plasma samples of mild and severe COVID-19 cases is described. Clusters of high siRNA abundance were discovered, homologous to the nsp2 3'-end and nsp4 virus sequence. Four virus-derived small RNA sequences have the size of human miRNAs, and a target search revealed candidate genes associated with ageusia and long COVID symptoms. These virus-derived small RNAs were detectable also after recovery from the disease. The additional analysis of circulating human miRNAs revealed differentially abundant miRNAs, discriminating mild from severe cases. A total of 29 miRNAs were reduced or absent in severe cases. Several of these are associated with JAK-STAT response and cytokine storm.

Operational characteristics of 30 lateral flow immunoassays used to identify COVID-19 immune response.

Serology or antibody tests for COVID-19 are designed to detect antibodies (mainly Immunoglobulin M (IgM) and Immunoglobulin G (IgG) produced in response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV-2) infection. In this study, 30 lateral flow immunoassays were tested using serum or plasma from patients with confirmed SARS CoV-2 infection. Negative serological controls were accessed from a well-characterised bank of sera which were stored prior to February 2020. Operational characteristics and ease of use of the assays are reported. 4/30 (13%) of kits (Zheihang Orient Gene COVID-19 IgG/IgM, Genrui Novel Coronavirus (2019-nCoV) IgG/IgM, Biosynex COVID-19 BSS IgG/IgM, Boson Biotech 2019-nCoV IgG/IgM) were recommended for SAHPRA approval based on kit sensitivity. Of these, only the Orientgene was recommended by SAHPRA in August 2020 for use within the approved national testing algorithm while the remaining three received limited authorization for evaluation. All kits evaluated work on the same basic principle of immunochromatography with minor differences noted in the shape and colour of cartridges, the amount of specimen volume required and the test duration. Performance of the lateral flow tests were similar to sensitivities and specificities reported in other studies. The cassettes of the majority of kits evaluated (90%) detected both IgG and IgM. Only 23% of kits evaluated contained all consumables required for point-of-care testing. The study highlights the need for thorough investigation of kits prior to implementation.

Unified platform for genetic and serological detection of COVID-19 with single-molecule technology.

The COVID-19 pandemic raises the need for diverse diagnostic approaches to rapidly detect different stages of viral infection. The flexible and quantitative nature of single-molecule imaging technology renders it optimal for development of new diagnostic tools. Here we present a proof-of-concept for a single-molecule based, enzyme-free assay for detection of SARS-CoV-2. The unified platform we developed allows direct detection of the viral genetic material from patients' samples, as well as their immune response consisting of IgG and IgM antibodies. Thus, it establishes a platform for diagnostics of COVID-19, which could also be adjusted to diagnose additional pathogens.

Liposome-mediated detection of SARS-CoV-2 RNA-positive extracellular vesicles in plasma.

Plasma SARS-CoV-2 RNA may represent a viable diagnostic alternative to respiratory RNA levels, which rapidly decline after infection. Quantitative PCR with reverse transcription (RT-qPCR) reference assays exhibit poor performance with plasma, probably reflecting the dilution and degradation of viral RNA released into the circulation, but these issues could be addressed by analysing viral RNA packaged into extracellular vesicles. Here we describe an assay approach in which extracellular vesicles directly captured from plasma are fused with reagent-loaded liposomes to sensitively amplify and detect a SARS-CoV-2 gene target. This approach accurately identified patients with COVID-19, including challenging cases missed by RT-qPCR. SARS-CoV-2-positive extracellular vesicles were detected at day 1 post-infection, and plateaued from day 6 to the day 28 endpoint in a non-human primate model, while signal durations for 20-60 days were observed in young children. This nanotechnology approach uses a non-infectious sample and extends virus detection windows, offering a tool to support COVID-19 diagnosis in patients without SARS-CoV-2 RNA detectable in the respiratory tract.

Durable antibody response one year after hospitalization for COVID-19: A longitudinal cohort study.

OBJECTIVES: Durability of the humoral immune response to SARS-CoV-2 has yet to be defined. We longitudinally evaluated during a 12-month period the antibody responses to SARS-CoV-2, and analysed predictors of antibody titres decline and seroreversion. METHODS: Prospective study conducted in a cohort of patients hospitalized for microbiologically-confirmed COVID-19. Blood and nasopharyngeal samples were sequentially obtained during hospital stay and at 1, 2, 6 and 12 months after patients' discharge for measuring anti-spike (S) and anti-nucleocapsid (N) IgG antibody levels and SARS-CoV-2 RNA, respectively. RESULTS: 80 non-vaccinated patients were analysed. At month 12 after discharge, 73 (91.2%) patients exhibited detectable S-IgG and 35 (43.8%) N-IgG antibody titres. A gradual wane was observed in S-IgG and N-IgG antibody titres. Linear regression showed that S-IgG decline was positively associated with peak antibody titres (coefficient [95% CI] 0.059 [0.05-0.067], p < 0.001), inversely with WHO severity score (coefficient [95% CI] -0.042 [-0.079/-0.004], p = 0.033), and there was a trivial positive association with age (coefficient [95% CI] 0.002 [0-0.005], p = 0.10); N-IgG decline was positively associated with peak antibody titres (coefficient [95% CI] 0.091 [0.078-0.105], p < 0.001). Logistic regression showed that seroreversion for S-IgG was inversely associated with peak S-IgG (OR 0.19; 95% CI, 0.04-0.45; p = 0.004); seroreversion for N-IgG was inversely associated with peak N-IgG (OR 0.71; 95% 0.53-0.90; p = 0.009) and positively with cycle threshold of RT-PCR (OR 1.14; 95% CI, 1.00-1.33; p = 0.062). CONCLUSION: Anti-spike IgG antibodies remain detectable one year after hospitalization for COVID-19. Higher peak antibody titres and disease severity were associated with increased durability of detectable antibodies.

Molecular evidence suggesting the persistence of residual SARS-CoV-2 and immune responses in the placentas of pregnant patients recovered from COVID-19.

OBJECTIVES: Recent studies have shown the presence of SARS-CoV-2 in the tissues of clinically recovered patients and persistent immune symptoms in discharged patients for up to several months. Pregnant patients were shown to be a high-risk group for COVID-19. Based on these findings, we assessed SARS-CoV-2 nucleic acid and protein retention in the placentas of pregnant women who had fully recovered from COVID-19 and cytokine fluctuations in maternal and foetal tissues. MATERIALS AND METHODS: Remnant SARS-CoV-2 in the term placenta was detected using nucleic acid amplification and immunohistochemical staining of the SARS-CoV-2 protein. The infiltration of CD14+ macrophages into the placental villi was detected by immunostaining. The cytokines in the placenta, maternal plasma, neonatal umbilical cord, cord blood and amniotic fluid specimens at delivery were profiled using the Luminex assay. RESULTS: Residual SARS-CoV-2 nucleic acid and protein were detected in the term placentas of recovered pregnant women. The infiltration of CD14+ macrophages into the placental villi of the recovered pregnant women was higher than that in the controls. Furthermore, the cytokine levels in the placenta, maternal plasma, neonatal umbilical cord, cord blood and amniotic fluid specimens fluctuated significantly. CONCLUSIONS: Our study showed that SARS-CoV-2 nucleic acid (in one patient) and protein (in five patients) were present in the placentas of clinically recovered pregnant patients for more than 3 months after diagnosis. The immune responses induced by the virus may lead to prolonged and persistent symptoms in the maternal plasma, placenta, umbilical cord, cord blood and amniotic fluid.