Correlating the differences in the receptor binding domain of SARS-CoV-2 spike variants on their interactions with human ACE2 receptor.

Spike glycoprotein of SARS-CoV-2 variants plays a critical role in infection and transmission through its interaction with human angiotensin converting enzyme 2 (hACE2) receptors. Prior findings using molecular docking and biomolecular studies reported varied findings on the difference in the interactions among the spike variants with the hACE2 receptors. Hence, it is a prerequisite to understand these interactions in a more precise manner. To this end, firstly, we performed ELISA with trimeric spike glycoproteins of SARS-CoV-2 variants including Wuhan Hu-1(Wild), Delta, C.1.2 and Omicron. Further, to study the interactions in a more specific manner by mimicking the natural infection, we developed hACE2 receptors expressing HEK-293T cell line, evaluated their binding efficiencies and competitive binding of spike variants with D614G spike pseudotyped virus. In line with the existing findings, we observed that Omicron had higher binding efficiency compared to Delta in both ELISA and Cellular models. Intriguingly, we found that cellular models could differentiate the subtle differences between the closely related C.1.2 and Delta in their binding to hACE2 receptors. Our study using the cellular model provides a precise method to evaluate the binding interactions between spike sub-lineages to hACE2 receptors.

A clinico-epidemiological profile, coinfections and outcome of patients with Influenza Like Illnesses (ILI) presenting to the emergency department during the COVID-19 pandemic.

Background: During the COVID-19 pandemic, many patients presented to the emergency department (ED) with features of Influenza-like illnesses (ILI) and with other atypical presentations. This study was done to determine the etiology, co-infections, and clinical profile of patients with ILI. Methods: This prospective observational study included all patients presenting to the ED with fever and/or cough, breathing difficulty, sore throat, myalgia, gastrointestinal complaints (abdominal pain/vomiting/diarrhea), loss of taste and altered sensorium or asymptomatic patients who resided in or travelled from containment zones, or those who had contact with COVID-19 positive patients during the first wave of the pandemic between April and August 2020. Respiratory virus screening was done on a subset of COVID-19 patients to determine co-infection. Results: During the study period, we recruited 1462 patients with ILI and 857 patients with the non-ILI presentation of confirmed COVID-19 infection. The mean age group of our patient population was 51.4 (SD: 14.9) years with a male predominance (n-1593; 68.7%). The average duration of symptoms was 4.1 (SD: 2.9) days. A sub-analysis to determine an alternate viral etiology was done in 293 (16.4%) ILI patients, where 54 (19.4%) patients had COVID 19 and co-infection with other viruses, of which Adenovirus (n-39; 14.0%) was the most common. The most common symptoms in the ILI-COVID-19 positive group (other than fever and/or cough and/or breathing difficulty) were loss of taste (n-385; 26.3%) and diarrhea (n- 123; 8.4%). Respiratory rate (27.5 (SD: 8.1)/minute: p-value < 0.001) and oxygen saturation (92.1% (SD: 11.2) on room air; p-value < 0.001) in the ILI group were statistically significant. Age more than 60 years (adjusted odds ratio (OR): 4.826 (3.348-6.956); p-value: <0.001), sequential organ function assessment score more than or equal to four (adjusted OR: 5.619 (3.526-8.957); p-value: <0.001), and WHO critical severity score (Adjusted OR: 13.812 (9.656-19.756); p-value: <0.001) were independent predictors of mortality. Conclusion: COVID-19 patients were more likely to present with ILI than atypical features. Co-infection with Adenovirus was most common. Age more than 60 years, SOFA score more than or equal to four and WHO critical severity score were independent predictors of mortality.

Omicron infection increases IgG binding to spike protein of predecessor variants.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in India in 2020-2022 was driven predominantly by Wild (Wuhan-Hu-1 and D614G), Delta, and Omicron variants. The aim of this study was to examine the effect of infections on the humoral immune response and cross-reactivity to spike proteins of Wuhan-Hu-1, Delta, C.1.2., and Omicron. Residual archival sera (N = 81) received between January 2020 and March 2022 were included. Infection status was inferred by a positive SARS-CoV-2 RT-PCR and/or serology (anti-N and anti-S antibodies) and sequencing of contemporaneous samples (N = 18) to infer lineage. We estimated the levels and cross-reactivity of infection-induced sera including Wild, Delta, Omicron as well as vaccine breakthrough infections (Delta and Omicron). We found an approximately two-fold increase in spike-specific IgG antibody binding in post-Omicron infection compared with the pre-Omicron period, whilst the change in pre- and post-Delta infections were similar. Further investigation of Omicron-specific humoral responses revealed primary Omicron infection as an inducer of cross-reactive antibodies against predecessor variants, in spite of the weaker degree of humoral response compared to Wuhan-Hu-1 and Delta infection. Intriguingly, Omicron vaccine-breakthrough infections when compared with primary infections, exhibited increased humoral responses against RBD (7.7-fold) and Trimeric S (Trimeric form of spike protein) (34.6-fold) in addition to increased binding of IgGs towards previously circulating variants (4.2 - 6.5-fold). Despite Delta breakthrough infections showing a higher level of humoral response against RBD (2.9-fold) and Trimeric S (5.7-fold) compared to primary Delta sera, a demonstrably reduced binding (36%-49%) was observed to Omicron spike protein. Omicron vaccine breakthrough infection results in increased intensity of humoral response and wider breadth of IgG binding to spike proteins of antigenically-distinct, predecessor variants.

Retrospective study of comparison of clinical severity and outcome of hospitalised COVID-19 patients during the first and second waves of the pandemic in India.

OBJECTIVES: To compare the clinical severity and outcome of hospitalised patients during the two waves of the COVID-19 pandemic in India. SETTING: A tertiary care referral hospital in South India. PARTICIPANTS: Symptomatic SARS CoV-2 reverse transcriptase PCR positive patients presenting to the emergency department during the two waves were recruited. The first wave spanned between April and December 2020 and the second wave between April and May 2021. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome of interest was mortality. Secondary outcomes included illness severity at presentation, need for oxygen therapy, non-invasive ventilation (NIV) and hospital or intensive care unit admission. RESULTS: The mean (SD) age of the 4971 hospitalised patients in the first wave was similar to the 2293 patients in the second wave (52.5±15.4 vs 52.1±15.1 years, p=0.37). When compared with the first wave, during the second wave, a higher proportion of patients presented with critical illness (11% vs 1.1%, p<0.001) and needed supplemental oxygen therapy (n=2092: 42.1% vs n=1459: 63.6%; p<0.001), NIV (n=643; 12.9% vs n=709; 30.9%; p<0.001) or inotropes/vasoactive drugs (n=108; 2.2% vs n=77: 3.4%; p=0.004). Mortality was higher during the second wave (19.2% vs 9.3%; p<0.001). On multivariable regression analysis, age >60 years (risk ratio, RR 2.80; 95% CI 2.12 to 3.70), D-dimer >1000 ng/mL (RR 1.34; 95% CI 1.15 to 1.55), treatment with supplemental oxygen (RR 14.6; 95% CI 8.98 to 23.6) and presentation during the second wave (RR 1.40; 95% CI 1.21 to 1.62) were independently associated with mortality. CONCLUSION: The second wave of the COVID-19 pandemic in India appeared to be associated with more severe presentation and higher mortality when compared with the first wave. Increasing age, elevated D-dimer levels and treatment with supplemental oxygen were independent predictors of mortality.

Three waves, three vaccines, three COVID-19 infections - Saga of a frontline health care worker during the pandemic.

The COVID-19 pandemic affected millions around the globe, with front line healthcare workers (HCW) amongst the most vulnerable. The Emergency Department (ED) was the first line of care for all patients infected with the virus, making HCWs in the ED one of the most exposed populations during the pandemic. We highlight the case of a 35-year-old ED physician who developed COVID-19 infections on three separate instances during the peaks of each wave despite the usage of personal protective equipment and being triple vaccinated.

Facilitating Safe Discharge Through Predicting Disease Progression in Moderate Coronavirus Disease 2019 (COVID-19): A Prospective Cohort Study to Develop and Validate a Clinical Prediction Model in Resource-Limited Settings.

BACKGROUND: In locations where few people have received coronavirus disease 2019 (COVID-19) vaccines, health systems remain vulnerable to surges in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Tools to identify patients suitable for community-based management are urgently needed. METHODS: We prospectively recruited adults presenting to 2 hospitals in India with moderate symptoms of laboratory-confirmed COVID-19 to develop and validate a clinical prediction model to rule out progression to supplemental oxygen requirement. The primary outcome was defined as any of the following: SpO2 < 94%; respiratory rate > 30 BPM; SpO2/FiO2 < 400; or death. We specified a priori that each model would contain three clinical parameters (age, sex, and SpO2) and 1 of 7 shortlisted biochemical biomarkers measurable using commercially available rapid tests (C-reactive protein [CRP], D-dimer, interleukin 6 [IL-6], neutrophil-to-lymphocyte ratio [NLR], procalcitonin [PCT], soluble triggering receptor expressed on myeloid cell-1 [sTREM-1], or soluble urokinase plasminogen activator receptor [suPAR]), to ensure the models would be suitable for resource-limited settings. We evaluated discrimination, calibration, and clinical utility of the models in a held-out temporal external validation cohort. RESULTS: In total, 426 participants were recruited, of whom 89 (21.0%) met the primary outcome; 257 participants comprised the development cohort, and 166 comprised the validation cohort. The 3 models containing NLR, suPAR, or IL-6 demonstrated promising discrimination (c-statistics: 0.72-0.74) and calibration (calibration slopes: 1.01-1.05) in the validation cohort and provided greater utility than a model containing the clinical parameters alone. CONCLUSIONS: We present 3 clinical prediction models that could help clinicians identify patients with moderate COVID-19 suitable for community-based management. The models are readily implementable and of particular relevance for locations with limited resources.

The role and diagnostic accuracy of serology for COVID-19.

BACKGROUND: The role and performance of various serological tests for the diagnosis of COVID-19 are unclear. This study aimed to evaluate the performance of seven commercially available serological assays for SARS-CoV-2 antibodies by testing COVID-19 cases and controls. METHODS: Adult patients with fever for > 5 days, admitted to a tertiary-care teaching hospital in South India, were enrolled prospectively between June and December 2020. SARS-CoV-2 RT-PCR confirmed patients were classified as cases, and patients with febrile illness with laboratory-confirmed alternative diagnosis and healthy participants were controls. All participants were tested with SCoV-2 Detect™ IgM ELISA kit and SCoV-2 Detect™ IgG ELISA kit (InBios International, Seattle, USA) (Inbios), SARS-CoV-2 Total and SARS-CoV-2 IgG (Siemens Healthcare Diagnostics Inc., Tarrytown, USA) (Siemens), Roche Elecsys® Anti-SARS-CoV-2 (Roche Diagnostics, Rotkreuz, Switzerland) (Roche), Abbott SARS-CoV-2 IgG (Abbott Diagnostics, IL, USA) (Abbott), and Liaison® SARS-CoV-2 S1/S2 IgG (DiaSorinS.p.A., Saluggia, Italy) (Liaison). The sensitivities, specificities, positive predictive values (PPV), negative predictive values (NPV), and accuracies were compared. RESULTS: There were 303 participants: 153 cases and 150 controls. ELISA detecting anti-S protein antibody was more sensitive (88.9% for IgG and 86.3% for IgM) than the CLIAs (82.4% for total antibodies and 76.5-85.6% for IgG). Among CLIAs, Roche IgG was most sensitive (85.6%) followed by Abbott (83%) and Liaison (83%). Abbot had the best PPV (88.8%) and was more specific (89.3%) than Liaison (82%) and Roche (82%). Siemens IgG was less sensitive (76.5%) than Siemens Total (82.4%). The specificity of all the serological assays was modest (75-90%). Antibody test positivity increased with the duration of illness reaching 90% after 10 days of illness. When cases were compared against pre-pandemic controls, the IgG gave excellent specificity (98-100%). For seroprevalence studies, InBios IgG had the best accuracy (90.8%) with 88.9% sensitivity and 97.6% specificity. CONCLUSION: The serological assays are important adjuncts for the diagnosis of COVID-19 in patients with persistent symptoms, especially in the second week of illness. The value of serological diagnostic tests is limited in the first week of illness and they provide additional value in seroprevalence studies. The diagnostic accuracy of the ELISA and CLIA platforms were comparable.

Single Dose of Ivermectin is not Useful in Patients with Hematological Disorders and COVID-19 Illness: A Phase II B Open Labelled Randomized Controlled Trial.

Repurposed drugs may reduce morbidity and mortality in patients with hematological disorders who develop COVID-19 illness. 112 patients with predominantly hematological illnesses were randomized to receive standard of care, ivermectin 12 mg [Iv 12] or 24 mg [Iv24] for asymptomatic, mild, or moderate COVID 19 illness. Serial respiratory samples for rRT-PCR samples were sent on Day 3, 5 and 7. rRT-PCR negativity and ≥ 2 log10 reduction in viral loads on day 3, 5 and 7 were similar between the 3 treatment groups across all disease categories. Symptom progression occurred in 26 patients [21.6%] with no difference across 3 treatment groups. Twenty-two patients [18.3%] have expired while 98 [81.7%] survived. Survival rates were similar across treatment groups [controls-80.5%, Iv12-77.5%, Iv24-87.2% respectively]. Overall, poorer survival was seen with moderate illness compared to others [51.6% vs 92.1%; p = 0.000] and was the only significant risk factor identified on multivariate analysis. In this Phase II randomised trial, single dose of 12 or 24 mg of ivermectin did not reduce viral loads, prevent symptom progression, or reduce mortality in patients with predominantly haematological illnesses who develop mild to moderate COVID 19 illness.

Optimization of SARS-CoV-2 Pseudovirion Production in Lentivirus Backbone With a Novel Liposomal System.

Due to the fast mutating nature of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the development of novel therapeutics, vaccines, and evaluating the efficacies of existing one's against the mutated strains is critical for containing the virus. Pseudotyped SARS-CoV-2 viruses are proven to be instrumental in evaluating the efficiencies of therapeutics, owing to their ease in application and safety when compared to handling the live virus. However, a comprehensive protocol that includes selecting transfection reagents, validating different packaging systems for high-throughput screening of neutralizing antibodies, is still a requisite. To this end, we designed and synthesized amide linker-based cationic lipids with varying hydrophilic head groups from dimethyl (Lipo-DME) to methyl, ethylhydroxyl (Lipo-MeOH), and diethylhydroxyl (Lipo-DOH) keeping the hydrophobic tail, stearic acid, as constant. Among the liposomal formulations of these lipids, Lipo-DOH was found to be superior in delivering plasmids and demonstrated comparable transfection efficiencies with commercial standard Lipofectamine 3000. We further used Lipo-DOH for lentivirus and SARS-CoV-2 pseudovirion preparation. For comparing different lentivirus packaging systems, we optimized conditions using Addgene and BEI systems and found that the BEI lenti plasmid system was found to be efficient in making lentiviruses using Lipo-DOH. Using the optimized transfection reagent and the lentivirus system, we developed a robust protocol for the generation of SARS-CoV-2 pseudovirions and characterized their infectivity in human ACE2 expressing HEK-293T cells and neutralizing properties in IgG against spike protein of SARS-CoV-2 positive human sera from individuals recovered from COVID-19.

Impact of the COVID-19 National Lockdown on a Rural and Tribal Population of Tamil Nadu, Southern India: A Mixed-Methods Survey.

We assessed the impact of the national lockdown on a rural and tribal population in Tamil Nadu, southern India. A mixed-methods approach with a pilot-tested, semi-structured questionnaire and focus group discussions were used. The impact of the lockdown on health, finances, and livelihood was studied using descriptive statistics. Multivariable logistic regression was carried out to identify factors associated with households that borrowed loans or sold assets during the lockdown, and unemployment during the lockdown. Of the 607 rural and tribal households surveyed, households from comparatively higher socioeconomic quintiles (adjusted odds ratio [aOR], 1.84; 95% CI, 1.01-3.34), with no financial savings (aOR, 2.91; 95% CI, 1.17-7.22), and with larger families (aOR, 1.76; 95% CI, 1.22-2.53), took loans or sold assets during the lockdown. Previously employed individuals from rural households (aOR, 5.07; 95% CI, 3.30-7.78), lower socioeconomic households (aOR, 3.08; 95% CI, 1.74, 5.45), and households with no savings (aOR, 1.78; 95% CI, 1.30-2.44) became predominantly unemployed during the lockdown. Existing government schemes for the elderly, differently abled, and widows were shown to be accessible to 89% of the individuals requiring these schemes in our survey. During the focus group discussions, the limited reach of online classes for schoolchildren was noted and attributed to the lack of smartphones and poor Internet connectivity. Although the sudden, unannounced national lockdown was imposed to flatten the COVID-19 curve, aspects related to livelihood and financial security were affected for both the rural and tribal populations.

Impact of prior vaccination with CovishieldTM and Covaxin® on mortality among symptomatic COVID-19 patients during the second wave of the pandemic in South India during April and May 2021: a cohort study.

BACKGROUND: COVID-19 vaccines were authorised for emergency use to mitigate the impact of the pandemic. This study evaluated the effect of prior vaccination with either Oxford Astra Zeneca's Covishield™ or Bharath Biotech's Covaxin® on mortality among symptomatic COVID-19 patients during the second wave of the pandemic in India. METHODOLOGY: In this cohort study comprising of RT-PCR confirmed symptomatic COVID-19 patients presenting during April and May 2021, the effect of prior vaccination on mortality (primary outcome), need for hospitalization, oxygen therapy, non-invasive ventilation (NIV) and intensive care unit (ICU) admission were assessed and expressed as risk ratio (RR) with 95% confidence intervals (CI). RESULTS: The mean (SD) age of the cohort (n = 4183) was 46.3 (15.5) years; 17.9% (748/4183) had received at least one dose of Covishield™ and 4.8% (201/4183) had received Covaxin®. Mortality was 0.2% (95% CI: 0.2% - 0.7%), 3.5% (1.9-5.2%), 6.2% (0.3-12%) and 12.9% (11.8-14.1%) among fully vaccinated (>2 weeks after two doses), partially vaccinated (>2 weeks after one dose or <2 weeks after two doses), indeterminate (<2 weeks after one dose) and unvaccinated patients respectively. The difference in mortality among unvaccinated vs. fully vaccinated was 12.7% (95% CI: 11.4-13.9%), unvaccinated vs. partially vaccinated was 9.4% (7.4-11.4%) and unvaccinated vs. indeterminate vaccinated was 6.8% (0.8-12.7%). On adjusted analysis, as compared to unvaccinated patients, at least one dose of vaccine reduced the need for hospitalization (RR: 0.40; 95% CI: 0.35-0.47), oxygen (0.33; 0.27-0.40), NIV (0.23; 0.17-0.32), ICU admission (0.18; 0.12-0.27) and mortality (0.18; 0.11-0.29). CONCLUSION: Among symptomatic COVID-19 patients, prior vaccination with Covishield ™ or Covaxin® impacted the severity of illness and reduced mortality during a period of widespread delta variant circulation. Full vaccination conferred greater protection than partial vaccination.

Community seroprevalence and risk factors for SARS-CoV-2 infection in different subpopulations in Vellore, India, and their implications for future prevention.

OBJECTIVES: The aim of this study was to inform public health policy decisions through the assessment of IgG antibody seroprevalence in the population and the risk factors for SARS-CoV-2 infection. METHODS: The seroprevalence of IgG antibodies among different subpopulations at the end of the first and second waves of the pandemic was estimated. Various risk factors associated with seropositivity, including sociodemography, IgG antibodies against endemic human coronavirus, and vaccination status, were also assessed. RESULTS: For all 2433 consenting participants, the overall estimated seroprevalences at the end of first and second waves were 28.5% (95% CI 22.3-33.7%) and 71.5% (95% CI 62.8-80.5%), respectively. The accrual of IgG positivity was heterogeneous, with the highest seroprevalences found in urban slum populations (75.1%). Vaccine uptake varied among the subpopulations, with low rates (< 10%) among rural and urban slum residents. The majority of seropositive individuals (75%) were asymptomatic. Residence in urban slums (OR 2.02, 95% CI 1.57-2.6; p < 0.001), middle socioeconomic status (OR 1.77, 95% CI 1.17-2.67; p = 0.007), presence of diabetes (OR 1.721, 95% CI 1.148-2.581; p = 0.009), and hypertension (OR 1.75, 95% CI 1.16-2.64; p = 0.008) were associated with seropositivity in multivariable analyses. CONCLUSION: Although considerable population immunity has been reached, with more than two-thirds seropositive, improved vaccination strategies among unreached subpopulations and high-risk individuals are suggested for better preparedness in future.

Recurrent COVID-19 infection in a case of rituximab-induced hypogammaglobulinaemia.

Patients with immunodeficiency are at an increased risk of recurrent COVID-19 infection. They may lack the natural immune response that usually confers long-lasting immunity. Here, we present our experience managing one such patient, who had a COVID-19 infection twice, 5 months apart. He had a positive SARS-CoV-2 real-time reverse transcription polymerase chain reaction (RT-PCR) and computed tomography (CT) thorax with classical findings of COVID-19 on both occasions. He had multiple negative RT-PCR tests and two CT scans without COVID-19 features between these two infections. While the antibody response to the first infection was not detectable, the response to the second infection was robust. Live attenuated vaccines are contraindicated in patients with immunodeficiency, and other vaccines may not elicit an adequate immune response. A high index of suspicion for recurrent COVID-19 is warranted in this group of patients.

The Unique Balancing Act of Managing Children With Cancer and COVID-19 Infection: A Single Center Experience From South India.

Children with cancer are vulnerable to severe infections. Balancing the intensive treatment of cancer, with the potential risk of coronavirus disease-2019 (COVID-19) related morbidity and mortality is a unique challenge. Children with cancer testing positive for severe acute respiratory syndrome coronavirus 2 virus by reverse-transcription polymerase chain reaction at our center were studied. Thirty-seven children tested positive for COVID-19 during the study period. The severity of the illness was mild, moderate, severe, and critical in 10 (27%), 13 (35%), 12 (32%), and 2 (5%) patients, respectively. Of the 14 patients with a severe/critical illness, 2 had oncological emergencies, 4 had dengue co-infection, and 1 had an inguinal bacterial abscess. All patients were discharged in a stable condition. Modification of the treatment protocol was performed in 11 (33%) of 33 patients who were on active treatment for cancer. There was a median delay of 32.5 days to administer the next cycle of chemotherapy in patients who acquired COVID-19 during cancer treatment. Six of 7 patients who were retested after 14 days remained positive by reverse-transcription polymerase chain reaction. Children with cancer with COVID-19 recover with good supportive care. Curative chemotherapy can be administered safely with appropriate modifications in children with cancer with COVID-19.

SARS-CoV-2 Laboratory Testing in India's Pandemic Response: A Public Health Perspective.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted (at the time of writing) in over 3.3 million cases and 233,000 deaths globally and ~33,000 cases and ~1,100 deaths in India. The mainstay of the diagnosis is a reverse-transcription polymerase chain reaction assay to detect SARS-CoV-2 RNA. The accurate diagnosis is contingent on appropriate specimen choice, time of collection, and assay employed. In this commentary, we highlight the role of laboratory diagnostic tests used in the different stages of India's COVID-19 pandemic response.