Immune Responses and Pathogenesis following Experimental SARS-CoV-2 Infection in Domestic Cats.

Several reports demonstrated the susceptibility of domestic cats to SARS-CoV-2 infection. Here, we describe a thorough investigation of the immune responses in cats after experimental SARS-CoV-2 inoculation, along with the characterization of infection kinetics and pathological lesions. Specific pathogen-free domestic cats (n = 12) were intranasally inoculated with SARS-CoV-2 and subsequently sacrificed on DPI (days post-inoculation) 2, 4, 7 and 14. None of the infected cats developed clinical signs. Only mild histopathologic lung changes associated with virus antigen expression were observed mainly on DPI 4 and 7. Viral RNA was present until DPI 7, predominantly in nasal and throat swabs. The infectious virus could be isolated from the nose, trachea and lungs until DPI 7. In the swab samples, no biologically relevant SARS-CoV-2 mutations were observed over time. From DPI 7 onwards, all cats developed a humoral immune response. The cellular immune responses were limited to DPI 7. Cats showed an increase in CD8+ cells, and the subsequent RNA sequence analysis of CD4+ and CD8+ subsets revealed a prominent upregulation of antiviral and inflammatory genes on DPI 2. In conclusion, infected domestic cats developed a strong antiviral response and cleared the virus within the first week after infection without overt clinical signs and relevant virus mutations.

Factors Associated With Prolonged Ventilation in Patients Receiving Prone Positioning Protocol With Muscle Relaxants for Severe COVID-19 Pneumonia.

BACKGROUND: Prone positioning and neuromuscular blocking agents (NMBAs) are frequently used to treat severe respiratory failure from COVID-19 pneumonia. Prone positioning has shown to improve mortality, whereas NMBAs are used to prevent ventilator asynchrony and reduce patient self-inflicted lung injury. However, despite the use of lung-protective strategies, high death rates in this patient population have been reported. METHODS: We retrospectively examined the factors affecting prolonged mechanical ventilation in patients receiving prone positioning plus muscle relaxants. The medical records of 170 patients were reviewed. Subjects were divided into 2 groups according to ventilator-free days (VFDs) at day 28. Whereas subjects with VFDs < 18 d were defined as prolonged mechanical ventilation, subjects with VFDs ≥18 d were defined as short-term mechanical ventilation. Subjects' baseline status, status at ICU admission, therapy before ICU admission, and treatment in the ICU were studied. RESULTS: Under the proning protocol for COVID-19, the mortality rate in our facility was 11.2%. The prognosis may be improved by avoiding lung injury in the early stages of mechanical ventilation. According to multifactorial logistic regression analysis, persistent SARS-CoV-2 viral shedding in blood (P = .027), higher daily corticosteroid use before ICU admission (P = .007), delayed recovery of lymphocyte count (P < .001), and higher maximal fibrinogen degradation products (P = .039) were associated with prolonged mechanical ventilation. A significant relationship was found between daily corticosteroid use before admission and VFDs by squared regression analysis (y = -0.00008522x2 + 0.01338x + 12.8; x: daily corticosteroids dosage before admission [prednisolone mg/d]; y: VFDs/28 d, R2 = 0.047, P = .02). The peak point of the regression curve was 13.4 d at 78.5 mg/d of the equivalent prednisolone dose, which corresponded to the longest VFDs. CONCLUSIONS: Persistent SARS-CoV-2 viral shedding in blood, high corticosteroid dose from the onset of symptoms to ICU admission, slow recovery of lymphocyte counts, and high levels of fibrinogen degradation products after admission were associated with prolonged mechanical ventilation in subjects with severe COVID-19 pneumonia.

Characteristics of viral shedding in people infected with SARS-CoV-2 during difference stages

Viral shedding of SARS-CoV-2 is a continuous dynamic process, which can be divided into latent stage, initial stage, peak stage and decreasing stage according to the characteristics of viral shedding. After being infected with SARS-CoV-2, the infected person generally stays in the latent period for 1-3 days, which is characterized by continuous negative nucleic acid test results and no infectiousness, and the risk of infection for close contacts is very low. At the initial stage of viral shedding is characterized by a rapid decline in the Ct value of nucleic acid tests in a short time, and clinical symptoms gradually appear. The infectiousness of the infected person gradually increases during this period, and the risk of infection for close contacts also gradually increases, but it is still in the early stage of infection, the possibility of viral shedding is low, and the risk of infection of secondary close contacts is low. The peak of viral shedding is characterized by low Ct value in nucleic acid test and obvious clinical symptoms;during this period, the infected person is the most infectious, and the risk of infection of the contact is the highest, so the scope of close contacts should be expanded appropriately. The decreasing period is characterized by the gradual increase of Ct value of nucleic acid test and the gradual disappearance of clinical symptoms;during this period, the infectiousness of the infected person gradually decreases to disappear. In an outbreak, an infected person in the decreasing phase is more likely to be an early infected person in the transmission chain. If infected individuals in the decreasing phase are found in an area without a SARS-CoV-2 epidemic, it suggests that the local outbreak epidemic has been spreading for some time and may be larger in scale. According to the characteristics of viral shedding, risk personnel can be determined more scientifically and accurately, so as to minimize the risk and reduce the waste of epidemic prevention resources.

The Association Between Stool Shedding of SARS-Cov-2 Microbiome Diversity and Intestinal Inflammation

Introduction: The transmission of the etiologic virus of COVID-19 (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) is thought to occur mainly via respiratory droplets even though limited evidence has shown the virus can be found in feces and involve the gastrointestinal (GI) tract. The aim of this study was to assess if patients with COVID-19 present with fecal shedding of SARS-CoV-2, intestinal inflammation or changes in their microbiota. Method(s): This was a prospective cohort study that included outpatients that presented with symptoms of COVID-19 and were tested using a nasopharyngeal PCR test (NPT). Two cohorts were selected: one with a (1) NPT and a control group with a (-) NPT. Stool and a clinical data were collected at baseline and then, days 14, 28 and 42. SARS-CoV-2 viral loads were measured in stool using PCR and stool microbiome was analyzed using 16S rRNA gene sequencing (V3/V4 region). Fecal calprotectin levels were also measured on each sample and used as a surrogate marker of intestinal inflammation. Result(s): 101 patients were recruited (410 total samples). Of those, 55 had a (1) COVID-19 NPT. Most patients with a (1) COVID-19 NPT PCR had a detectable fecal viral load (71%). Among these patients, 23 (55%) had detectable viral stool loads only at baseline, 12 through day 14, 6 through day 28 and 1 through day 42. One patient had a (-) NPT but detectable SARS-CoV-2 in the baseline stool sample. Subjects with (1) NPT presented more commonly with myalgias (p=0.02), dysgeusia (p=0.019) and anosmia (p=0.03) when compared to those with (-) NPT but there were no differences in any other symptoms including GI manifestations.Within the group with a (1) NPT, those patient with detectable SARS-CoV-2 in the stool were younger but no differences were seen in demographic, symptoms, or fecal calprotectin levels (Table). There was no correlation between fecal SARS-CoV-2 loads and fecal calprotectin levels (rho: 0.007 [p=0.95]). Patients with a (1) NPT PCR had higher evenness when compared to those that tested (-) for a NPT PCR. However, no differences were seen in other alpha or beta diversity (Figures 1A and 1B, respectively). Conclusion(s): Even though intestinal viral shedding of SARS-CoV-2 in patients with COVID-19 is common, these patients do not present with evidence of inflammation of the GI tract, a significantly disrupted gut microbiome or a higher incidence of GI symptoms when compared to patients with respiratory symptoms and no COVID-19.

Duration of SARS-CoV-2 RNA Shedding Is Significantly Influenced by Disease Severity, Bilateral Pulmonary Infiltrates, Antibiotic Treatment, and Diabetic Status: Consideration for Isolation Period.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) ribonucleic acid (RNA) shedding is an important parameter for determining the optimal length of isolation period required for coronavirus disease 2019 (COVID-19) patients. However, the clinical (i.e., patient and disease) characteristics that could influence this parameter have yet to be determined. In this study, we aim to explore the potential associations between several clinical features and the duration of SARS-CoV-2 RNA shedding in patients hospitalized with COVID-19. A retrospective cohort study involving 162 patients hospitalized for COVID-19 in a tertiary referral teaching hospital in Indonesia was performed from June to December 2021. Patients were grouped based on the mean duration of viral shedding and were compared based on several clinical characteristics (e.g., age, sex, comorbidities, COVID-19 symptoms, severity, and therapies). Subsequently, clinical factors potentially associated with the duration of SARS-CoV-2 RNA shedding were further assessed using multivariate logistic regression analysis. As a result, the mean duration of SARS-CoV-2 RNA shedding was found to be 13 ± 8.44 days. In patients with diabetes mellitus (without chronic complications) or hypertension, the duration of viral shedding was significantly prolonged (≥13 days; p = 0.001 and p = 0.029, respectively). Furthermore, patients with dyspnea displayed viral shedding for longer durations (p = 0.011). The multivariate logistic regression analysis reveals that independent risk factors associated with the duration of SARS-CoV-2 RNA shedding include disease severity (adjusted odds ratio [aOR] = 2.94; 95% CI = 1.36-6.44), bilateral lung infiltrates (aOR = 2.79; 95% CI = 1.14-6.84), diabetes mellitus (aOR = 2.17; 95% CI = 1.02-4.63), and antibiotic treatment (aOR = 3.66; 95% CI = 1.74-7.71). In summary, several clinical factors are linked with the duration of SARS-CoV-2 RNA shedding. Disease severity is positively associated with the duration of viral shedding, while bilateral lung infiltrates, diabetes mellitus, and antibiotic treatment are negatively linked with the duration of viral shedding. Overall, our findings suggest the need to consider different isolation period estimations for specific clinical characteristics of patients with COVID-19 that affect the duration of SARS-CoV-2 RNA shedding.

Vaccination status for mild and asymptomatic infections with SARS-CoV-2 Omicron BA.2 variant in Shanghai.

This study aimed to evaluate the effects of different vaccine regimens on mild and asymptomatic infections with SARS-CoV-2 Omicron BA.2 variant in Shanghai. All asymptomatic patients and those with mild symptoms of Omicron infections were recruited from three major Fangcang shelter hospitals between March 26, 2022 and May 20, 2022. Nucleic acid for SARS-CoV-2 by real-time reverse-transcription polymerase chain reaction methods in nasopharyngeal swabs was assessed every day during the hospitalization. The value of cycle threshold lower than 35 was considered as positive result of SARS-CoV-2. A total of 214 592 cases were included in this study. The proportion of the asymptomatic patients was 76.90% and 23.10% of the recruited patients had mild symptoms. The median (interquartile range [IQR]: 25-75) duration of viral shedding (DVS) was 7 (5-10) days among all participants. The DVS varied greatly among different age groups. Children and the elderly had longer DVS compared with the adults. The booster shot of inactivated vaccine contributed to the shorter DVS in patients aged ≥70 years compared with the unvaccinated patients (8 [6-11] vs. 9 [6-12] days, p = 0.002]. Full inactivated vaccine regimen contributed to the shorter DVS in patients aged 3-6 years (7 [5-9] vs. 8 [5-10] days, p = 0.001]. In conclusion, the full inactivated vaccine regimen on children aged 3-6 years and booster inactivated vaccine regimen on the elderly aged ≥70 years appeared to be effective in reducing DVS. The booster vaccine regimen should be rigorously promoted and implemented.

Nomogram for Predicting Viral Shedding Time of SARS-CoV-2 Delta Variant in Patients with COVID-19: A Retrospective Study

Background The coronavirus disease 2019 (COVID-19) cases continue to rise, and the demand for medical treatment and resources in healthcare systems surges. Assessing the viral shedding time (VST) of patients with COVID-19 can facilitate clinical decision making. Although some studies have been conducted on the factors affecting the VST of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), few prediction models are currently available. Methods This retrospective study included the consecutive patients with COVID-19 admitted to Xi'an Chest Hospital in Shaanxi, China, for treatment between December 19, 2021 and February 5, 2022. The clinical data of the patients were extracted from their electronic medical records. Combining significant factors affecting the VST, a nomogram was developed to predict the VST of the SARS-CoV-2 Delta variant in patients with COVID-19. Results We included 332 patients in this study. The average VST was 21 d. VST was significantly prolonged in patients with severe clinical symptoms, sore throat, old age, long time from onset to diagnosis, and an abnormal white blood cell count. Consequently, we developed a nomogram prediction model using these 5 variables. The concordance index (C-index) of this nomogram was 0.762, and after internal validation using bootstrapping (1000 resamples), the adjusted C-index was 0.762. The area under the nomogram's receiver operator characteristic curve showed good discriminative ability (0.965). The calibration curve showed high consistency. The VST was prolonged in the group with lower model fitting scores according to the Kaplan-Meier curve (χ2=286, log-rank P < 0.001). Conclusions We developed a nomogram for predicting VST based on 5 easily accessible factors. It can effectively estimate the appropriate isolation period, control viral transmission, and optimize clinical strategies. © Wolters Kluwer Health, Inc. All rights reserved.

Excreción de SARS-CoV-2 infeccioso en dos niños asintomáticos

Asymptomatic infections with SARS-CoV-2 are associated with viral transmission and have a key role in the propagation of the pandemic. Understanding viral shedding during asymptomatic infections is critical. Unfortunately, data on asymptomatic SARS-CoV-2 infection in children is extremely limited. To determine the presence of viral viable shedding, we prospectively followed two healthy children of a family where both parents developed mild COVID-19 (April 2021). SARS-CoV-2 detection was made by RT-PCR and virus isolation by cell culture from saliva samples. Positive samples were sequenced to identify variants of SARS-CoV-2. Serum samples were evaluated to determine the presence of antibodies using a single enzyme-linked immunosorbent assay (ELISA, COVIDAR IgG). Both children were SARS-CoV-2 positive and asymptomatic. In addition, the virus grew in cell culture from saliva samples. Furthermore, one child showed viable SARS-CoV-2 for at least 17 days after the onset symptoms from his father. The recommended isolation period for asymptomatic contacts during the acquisition of data had been established for 10 days;however, this child remained with viable virus beyond that period. The positive samples from both children were consistent with B.1.1.28.1 lineage (Gamma). In both asymptomatic children, anti-Spike IgG was detected. Asymptomatic children may represent a source of infection that should not be underestimated during this pandemic. Las infecciones asintomáticas por SARS-CoV-2 están asociadas a la transmisión viral y tienen un papel clave en la propagación de la pandemia. Comprender la excreción viral durante las infecciones asintomáticas es fundamental. Desafortunadamente, los datos sobre la infección asintomática por SARS-CoV-2 en niños son extremadamente limitados. Para determinar la presencia de excreción de virus viable, se siguió prospectivamente a dos niños sanos de una familia en la que ambos padres desarrollaron COVID-19 leve (abril 2021). La detección de SARS-CoV-2 se realizó por RT-PCR y el aislamiento del virus por cultivo celular a partir de muestras de saliva. Las muestras positivas se secuenciaron para identificar variantes de SARS-CoV-2. En las muestras de suero se determinó la presencia de anticuerpos utilizando un ensayo de ELISA (COVIDAR IgG). Ambos niños fueron positivos para SARS-CoV-2 y asintomáticos. Además, el virus creció en cultivos celulares a partir de muestras de saliva. Uno de los niños mantuvo SARS-CoV-2 viables durante al menos 17 días después de la aparición de los síntomas de su padre. El período de aislamiento recomendado para contactos asintomáticos durante la adquisición de datos se había establecido en 10 días, sin embargo, este niño permaneció con virus viable más allá de ese período. Las muestras positivas de estos niños correspondieron al linaje B.1.1.28.1 (Gamma). En ambos niños asintomáticos se detectó anticuerpos IgG anti-Spike. Concluimos que los niños asintomáticos pueden representar una fuente de infección que no debe subestimarse durante esta pandemia.

Interferon 1beta-1a ring prophylaxis to reduce household transmission of SARS-CoV-2

Introduction/Aim: Accumulating evidence indicates that an early, robust type 1 interferon (IFN) response to SARS-CoV-2 is critical for COVID-19 outcomes. Our objective was to examine the prophylactic potential of IFN treatment to limit viral transmission Methods: A cluster-randomised clinical trial was undertaken to determine effects of IFNbeta-1a treatment on SARS-CoV-2 household transmission (clinicaltrials.gov: NCT04552379). Index cases were identified from confirmed SARS-CoV-2 cases in Santiago, Chile, with 341 index cases and 831 household contacts enrolled. Households received 125 mug subcutaneous pegylated-IFNbeta-1a on days 1, 6, & 11 (172 households, 607 participants), or standard care (169 households, 565 participants). Primary outcomes included: (1) duration of viral shedding in infected cases (IC-INF), (2) transmission to treatment-eligible household contacts (EHC-ITT) at day 11. Result(s): Of 1172 individuals randomised, 53 individuals withdrew from the study (IFNbeta-1a = 35, SOC = 18). Eighty-two households (IFNbeta-1a = 36, SOC = 46) where the index case was SARS-CoV-2 negative on days 1 & 6, or with no SARS-CoV-2 negative contacts at recruitment, were excluded from exploratory analyses. Treatment with IFNbeta-1a: had no effect on duration of viral shedding in the IC-INF population (primary outcome 1), had no effect on transmission of SARS-CoV-2 at day 11 in the EHC-ITT population (primary outcome 2) but an effect was observed in a sensitivity analysis at day 6 (EHC-ITT: OR = 0.493, 95% CI = 0.256-0.949), reduced duration of hospitalisation in the IC-INF population and incidence of hospitalisation in per-protocol index cases (secondary outcome 3). In exploratory frequentist analysis, a significant effect of IFNbeta-1a treatment on SARS-CoV-2 transmission by day 11 (OR = 0.55, 95% CI = 0.36-0.99), and a Bayesian analysis identified a significant reduction in the odds of transmission (OR = -0.85, 95% credible interval = -1.59--0.16). Conclusion(s): Ring prophylaxis with IFNbeta-1a had no effect on duration of viral shedding but reduces the probability of SARS-CoV-2 transmission to uninfected, post-exposure contacts within a household.

IMMUNE STATUS AND SARS-CoV-2 VIRAL DYNAMICS

Background: Immunocompromised persons are disproportionately affected by severe SARS-CoV-2 infection, but immune compromise is heterogenous, which may impact viral dynamics. We hypothesized that higher degrees of compromised immunity are associated with higher viral shedding and slower viral clearance in the absence of COVID-19 therapeutics. Method(s): Participants enrolled in ACTIV-2/A5401, a platform trial for COVID-19 therapeutics in non-hospitalized adults within 10 days of symptom onset, received either an active treatment or placebo between 8/2020 and 7/2021. Participants were categorized based on the extent of immunosuppression into none, mild, moderate and severe categories at enrollment (day 0). Longitudinal anterior nasal (AN) and plasma SARS-CoV-2 levels were measured with a quantitative PCR assay. Regression models assessed associations between immunocompromise severity and viral levels (VL) at day 0, and longitudinally among those on placebo with quantifiable RNA at day 0. Multivariate analyses adjusted for demographics and symptom duration and vaccination status at day 0. Result(s): Immunocompromised (mild 383, moderate 159, severe 35) and immunocompetent (1956) participants had comparable symptom durations at day 0 (median 6 days) and most were unvaccinated (~95%). AN VL at day 0 was higher in the moderate/severe group compared to the immunocompetent group (adjusted difference in means: 0.47 log10 copies/mL, 95% CI 0.12, 0.83). While AN VL decayed at similar rates among all groups from day 0 to 3, there was a trend towards higher cumulative AN VLs across the 28-day follow-up in the moderate/severe group compared to immunocompetent group (adjusted fold difference in VL AUC 1.63, 95%CI 0.95, 2.77). The mild group showed no differences in day 0 VL or AUC compared to the immunocompetent group. The frequency of detectable plasma SARS-CoV-2 RNA was similar at day 0 across all groups (overall 21%), but there appeared to be a higher proportion of immunocompromised participants with detectable plasma viral RNA at day 7 (moderate/severe 2/23 [9%], mild 5/44 [11%]) compared to the immunocompetent group (8/282, 3%). Conclusion(s): Before emergence of Omicron and widespread vaccination, moderate/severe immunocompromised status was associated with higher nasal viral levels at study enrollment and showed a trend towards higher cumulative AN viral load, and all immunocompromised groups appeared to have more persistent plasma viremia during follow-up.

Prolonged Viable Viral Shedding in Immunocompromised Patients with Covid-19

Background: Immunocompromised patients with COVID-19 tend to shed viable virus for a prolonged period. Therefore, for moderately or severely immunocompromised patients with COVID-19, CDC recommends an isolation period of at least 20 days and ending isolation in conjunction with serial testing and consultation with an infectious disease specialist. However, data on viral kinetics and risk factors for prolonged viral shedding in these patients are limited. Method(s): From February 1, 2022 to April 1, 2022, we collected weekly saliva samples from immunocompromised patients with COVID-19 admitted to a tertiary hospital in Seoul, South Korea. Genomic and subgenomic RNAs were measured, and virus culture was performed. Result(s): A total of 41 patients were enrolled;29 (70%) were receiving chemotherapy against hematologic malignancies and the remaining 12 (30%) had undergone solid organ transplantation. Of the 41 patients, 14 (34%) had received 3 doses or more of COVID-19 vaccines. Real-time RT-PCR revealed that 7 (17%) were infected with Omicron BA.1, and 33 (80%) with Omicron BA.2. The median duration of viable virus shedding was 4 weeks (IQR 3-6). Patients undergoing B-cell depleting therapy shed viable virus for longer than the comparator (p=0.01). Multivariable analysis showed that 3-dose or more vaccination (HR 0.33, 95% CI 0.12 - 0.93, p = 0.04) and B-cell depleting therapy (HR 12.50, 95% CI 2.44 - 100.00, p = 0.003) independently affected viable virus shedding of SARS-CoV-2. Conclusion(s): Immunocompromised patients with COVID-19 shed viable virus for median 4 weeks. B-cell depleting therapy increases the risk of prolonged viable viral shedding, while completion of a primary vaccine series reduces this risk. Overall distribution of samples according to genomic viral copy number and culture positivity. Red dot indicates positive culture results, whereas blue dot indicated negative culture results. (Figure Presented).

Atypical Course of SarsCov-2 Infection in a Patient with Multiple Myeloma Treated with Autologous Stem Cell Transplantation

Covid-19 infection has more relevant consequences in frail and comorbid patients but little is known about its course in patients with hematologic malignancies. In this report we would like to present the case of a patient with multiple myeloma treated with recent autologous bone marrow stem cell transplantation and affected by Covid-19 pneumonia, presenting with a possible reinfection or an extremely long viral shedding.Copyright © 2023 Tehran University of Medical Sciences.

PROLONGED SARS-CoV-2 VIRAL BURDEN IN SIV-SARS-CoV-2 COINFECTED MACAQUES

Background: Individuals living with HIV are at increased risk of morbidity and mortality from COVID-19. Furthermore, SARS-CoV-2 infection in immunocompromised HIV infected individuals poses a risk to prolonged infection and viral shedding and the emergence of new variants of concern (VOCs). Using the SIV macaque model for AIDS, we are investigating the hypothesis that immune dysfunction during HIV infection will prolong SARSCoV- 2 viral infection, promote enhanced COVID-19 disease, and accelerate viral evolution. Here, we report the impact of SIV-CoV-2 co-infection on immune responses and pathogenesis. Method(s): Eight female rhesus macaques (aged 7-15 years, 5.5-9.9kg) were infected with SIVmac251 via low dose intravaginal challenge and then inoculated with 6.5x105 TCID50/mL SARS-CoV-2 (WA-1) at 17-34 weeks post-SIV infection via combined intranasal and intratracheal routes. Blood, bronchoalveolar lavage (BAL), stool, and nasal, oral, and rectal swabs were collected pre-infection through 14 days post-infection (DPI) to measure immune responses and viremia. ELISAs, ELISPOT, qRT-PCR, lung pathology, cytokine multiplex, and virus neutralization assays were performed to measure viral loads, pathogenesis, and immune responses. Result(s): Three days post-SARS-CoV-2 infection, we observed a transient decrease in CD4 counts, but there were no changes in clinical symptoms or plasma SIV viral loads. However, SARS-CoV-2 replication persisted in the upper respiratory tract, but not the lower respiratory tract. In addition, SARS-CoV-2 IgG seroconversion was delayed and antigen-specific T-cell responses were dampened. Notably, viral RNA levels in nasal swabs were significantly higher 7-14 DPI in SIV+ compared to previously published results using the same SARS-CoV-2 challenge virus in SIV- rhesus (PMCID: PMC8462335, PMC8829873). In addition, SIV/CoV-2 co-infected animals exhibited elevated levels of myeloperoxidase (MPO), a marker of neutrophil activation and increased lung inflammation. Conclusion(s): Here we provide evidence for the utility of the rhesus macaque in modeling human HIV-SARS-CoV-2 co-infection. Our results suggest that immunosuppression during SIV infection impairs de novo generation of anti-SARS-CoV-2 immunity, that may contribute to prolonged SARS-CoV-2 viral shedding, increased transmission windows, altered disease pathogenesis, and lower protection against subsequent SARS-CoV-2 exposures. Studies in progress will determine if SARS-CoV-2 viral evolution is accelerated in SIV-infected macaques.

NILMATREVIR-RITONAVIR TREATMENT IN CHILDREN WITH SARS-CoV-2 INFECTION

Background: Children seem to experience a less severe form of COVID-19 disease than adults, nevertheless, cases of severe infection have been described in a small proportion of patients, requiring hospitalization in 5-10% of cases. Among COVID-19 deaths 0,4% occurred in children and adolescents under 20 years of age. Most hospitalized children with acute COVID-19 had underlying conditions. Moreover, some children with previous COVID-19 infection, may later develop Multisystem Inflammatory Syndrome in Children (MIS-C), a rare but serious condition associated with COVID-19. These data suggest that a specific therapy is necessary in high-risk pediatric population, in order to prevent severe COVID-19, especially in children with underlying conditions. Antiviral paediatric data are currently very few Methods: We conducted a retrospective study on patients < 18 years of age who received Paxlovid (nirmatrelvir-ritonavir) for the treatment of mild-tomoderate COVID-19 at Bambino Gesu Children's Hospital from April 2022 to September 2022. Patients at high risk of progression to severe COVID-19 who had no need of supplemental oxygen received Paxlovid according to AIFA's indications for adults with the Informed Consent of relatives Results: 40 patients aged 1-18 years with confirmed SARS-CoV-2 infection were treated with Paxlovid (Tab 1)The average symptom duration was 4.2 days. No patient developed severe COVID-19 r All patients were treated within 5 days of symptom onset, Four patients received a longer course treatment (10 days) due to the persistence of symptoms combined with the presence of severe comorbidities .The mean time of viral shedding was 12.7 days, with a patient being persistently positive for 56 days. After Paxlovid initiation, only 5 patients (12.5%) experienced adverse reactions: Conclusion(s): Treatment with Paxlovid has proven to be safe. Further pharmacokinetic studies are required species for children < 5 years old.

A Nomogram for Predicting Delayed Viral Shedding in Non-Severe SARS-CoV-2 Omicron Infection.

Purpose: The Omicron variant of SARS-CoV-2 has emerged as a significant global concern, characterized by its rapid transmission and resistance to existing treatments and vaccines. However, the specific hematological and biochemical factors that may impact the clearance of Omicron variant infection remain unclear. The present study aimed to identify easily accessible laboratory markers that are associated with prolonged virus shedding in non-severe patients with COVID-19 caused by the Omicron variant. Patients and Methods: A retrospective cohort study was conducted on 882 non-severe COVID-19 patients who were diagnosed with the Omicron variant in Shanghai between March and June 2022. The least absolute shrinkage and selection operator regression model was used for feature selection and dimensional reduction, and multivariate logistic regression analysis was performed to construct a nomogram for predicting the risk of prolonged SARS-CoV-2 RNA positivity lasting for more than 7 days. The receiver operating characteristic (ROC) curve and calibration curves were used to assess predictive discrimination and accuracy, with bootstrap validation. Results: Patients were randomly divided into derivation (70%, n = 618) and validation (30%, n = 264) cohorts. Optimal independent markers for prolonged viral shedding time (VST) over 7 days were identified as Age, C-reactive protein (CRP), platelet count, leukocyte count, lymphocyte count, and eosinophil count. These factors were subsequently incorporated into the nomogram utilizing bootstrap validation. The area under the curve (AUC) in the derivation (0.761) and validation (0.756) cohorts indicated good discriminative ability. The calibration curve showed good agreement between the nomogram-predicted and actual patients with VST over 7 days. Conclusion: Our study confirmed six factors associated with delayed VST in non-severe SARS-CoV-2 Omicron infection and constructed a Nomogram which may assist non-severely affected patients to better estimate the appropriate length of self-isolation and optimize their self-management strategies.

Different effects of vaccine on VST in critical and non-critical COVID-19 patients: A retrospective study of 363 cases.

Aim: To explore the risk factors of prolonged viral shedding time (VST) in critical/non-critical COVID-19 patients during hospitalization. Methods: In this retrospective study, we enrolled 363 patients with SARS-CoV-2 infection admitted in a designated hospital during the COVID-19 outbreak in Nanjing Lukou International Airport. Patients were divided into critical (n = 54) and non-critical (n = 309) groups. We analyzed the relationship between the VST and demographics, clinical characteristics, medications, and vaccination histories, respectively. Results: The median duration of VST was 24 d (IQR, 20-29) of all patients. The VST of critical cases was longer than non-critical cases (27 d, IQR, 22.0-30.0 vs. 23 d, IQR 20-28, P < 0.05). Cox proportional hazards model showed that ALT (HR = 1.610, 95%CI 1.186-2.184, P = 0.002) and EO% (HR = 1.276, 95%CI 1.042-1.563, P = 0.018) were independent factors of prolonged VST in total cases; HGB (HR = 0.343, 95%CI 0.162-0.728, P = 0.005) and ALP (HR = 0.358, 95%CI 0.133-0.968, P = 0.043) were independent factors of prolonged VST in critical cases, while EO% (HR = 1.251, 95%CI 1.015-1.541, P = 0.036) was the independent factor of prolonged VST in non-critical cases. Vaccinated critical cases showed higher levels of SARS-CoV-2-IgG (1.725 S/CO, IQR 0.3975-28.7925 vs 0.07 S/CO, IQR 0.05-0.16, P < 0.001) and longer VSTs (32.5 d, IQR 20.0-35.25 vs 23 d, IQR 18.0-30.0, P = 0.011) compared with unvaccinated critical patients. Fully vaccinated non-critical cases, however, presented higher levels of SARS-CoV-2-IgG (8.09 S/CO, IQR 1.6975-55.7825 vs 0.13 S/CO IQR 0.06-0.41, P < 0.001) and shorter VSTs (21 d, IQR 19.0-28.0 vs 24 d, IQR 21.0-28.5, P = 0.013) compared with unvaccinated non-critical patients. Conclusions: Our results suggested that risk factors of prolonged VST were different between critical and non-critical COVID-19 patients. Increased level of SARS-CoV-2-IgG and vaccination did not shorten the VST and hospital stay in critical COVID-19 patients.

Immunization with Recombinant Accessory Protein-Deficient SARS-CoV-2 Protects against Lethal Challenge and Viral Transmission.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a worldwide coronavirus disease 2019 (COVID-19) pandemic. Despite the high efficacy of the authorized vaccines, there may be uncertain and unknown side effects or disadvantages associated with current vaccination approaches. Live-attenuated vaccines (LAVs) have been shown to elicit robust and long-term protection by the induction of host innate and adaptive immune responses. In this study, we sought to verify an attenuation strategy by generating 3 double open reading frame (ORF)-deficient recombinant SARS-CoV-2s (rSARS-CoV-2s) simultaneously lacking two accessory ORF proteins (ORF3a/ORF6, ORF3a/ORF7a, and ORF3a/ORF7b). We report that these double ORF-deficient rSARS-CoV-2s have slower replication kinetics and reduced fitness in cultured cells compared with their parental wild-type (WT) counterpart. Importantly, these double ORF-deficient rSARS-CoV-2s showed attenuation in both K18 hACE2 transgenic mice and golden Syrian hamsters. A single intranasal dose vaccination induced high levels of neutralizing antibodies against SARS-CoV-2 and some variants of concern and activated viral component-specific T cell responses. Notably, double ORF-deficient rSARS-CoV-2s were able to protect, as determined by the inhibition of viral replication, shedding, and transmission, against challenge with SARS-CoV-2 in both K18 hACE2 mice and golden Syrian hamsters. Collectively, our results demonstrate the feasibility of implementing the double ORF-deficient strategy to develop safe, immunogenic, and protective LAVs to prevent SARS-CoV-2 infection and associated COVID-19. IMPORTANCE Live-attenuated vaccines (LAVs) are able to induce robust immune responses, including both humoral and cellular immunity, representing a very promising option to provide broad and long-term immunity. To develop LAVs for SARS-CoV-2, we engineered attenuated recombinant SARS-CoV-2 (rSARS-CoV-2) that simultaneously lacks the viral open reading frame 3a (ORF3a) in combination with either ORF6, ORF7a, or ORF7b (Δ3a/Δ6, Δ3a/Δ7a, and Δ3a/Δ7b, respectively) proteins. Among them, the rSARS-CoV-2 Δ3a/Δ7b was completely attenuated and able to provide 100% protection against an otherwise lethal challenge in K18 hACE2 transgenic mice. Moreover, the rSARS-CoV-2 Δ3a/Δ7b conferred protection against viral transmission between golden Syrian hamsters.

Prolonged infective SARS-CoV-2 omicron variant shedding in a patient with diffuse large B cell lymphoma successfully cleared after three courses of remdesivir.

We report a case of prolonged shedding of the infective SARS-CoV-2 omicron variant BA.1.1.2 in a 79-year-old male patient with diffuse large B-cell lymphoma, after receiving chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP). The patient was admitted to our hospital in late March 2022 for the sixth course of R-CHOP chemotherapy. Initially, the patient tested negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using an in-hospital loop-mediated amplification assay with a nasopharyngeal swab, both on the day of admission and three days later. However, the patient developed fever and was diagnosed with coronavirus disease (COVID-19) six days after admission and was suspected to have contracted the infection in the ward. Viral shedding continued for more than three months, with confirmed viral infectivity. As compared to the original Wuhan-Hu-1/2019 strain, amino acid substitutions including S36 N in non-structural protein (NSP)2, S148P, S1265del and L1266I in NSP3, G105D in NSP4, G496S, A831V, or V987F in spike protein, and I45T in open-reading frame (ORF)9b were randomly detected in isolated viruses. Although the patient had received two doses of the BNT162b2 vaccine approximately six months earlier and the third dose on day 127 after the infection, both serum anti-spike and anti-nuclear protein IgG and IgM tests were negative at day 92, 114, and 149 after the infection. The patient finally cleared the virus after the third course of remdesivir and did not have further recurrence.

Fractional–Order Modeling and Control of COVID-19 with Shedding Effect

A fractional order COVID-19 model consisting of six compartments in Caputo sense is constructed. The indirect transmission of the virus through susceptible populations by the shedding effect is studied. Equilibrium solutions are calculated, and basic reproduction ratio (that depends both on direct and indirect mode of transmission), existence and uniqueness, as well as stability analysis of the solution of the model, are studied. The paper studies the effect of optimal control policy applied to shedding effect. The control is the observation of standard hygiene practices and chemical disinfectants in public spaces. Numerical simulations are carried out to support the analytic result and to show the significance of the fractional order from the biological viewpoint.