Quest for Optimal Regression Models in SARS-CoV-2 Wastewater Based Epidemiology

Wastewater-based epidemiology is a recognised source of information for pandemic management. In this study, we investigated the correlation between a SARS-CoV-2 signal derived from wastewater sampling and COVID-19 incidence values monitored by means of individual testing programs. The dataset used in the study is composed of timelines (duration approx. five months) of both signals at four wastewater treatment plants across Austria, two of which drain large communities and the other two drain smaller communities. Eight regression models were investigated to predict the viral incidence under varying data inputs and pre-processing methods. It was found that population-based normalisation and smoothing as a pre-processing of the viral load data significantly influence the fitness of the regression models. Moreover, the time latency lag between the wastewater data and the incidence derived from the testing program was found to vary between 2 and 7 days depending on the time period and site. It was found to be necessary to take such a time lag into account by means of multivariate modelling to boost the performance of the regression. Comparing the models, no outstanding one could be identified as all investigated models are revealing a sufficient correlation for the task. The pre-processing of data and a multivariate model formulation is more important than the model structure.

Factors Associated With Virological Suppression of HIV Viral Load in Patients on Antiretroviral Therapy in Conakry, Guinea

BackgroundThe viral load has become an indispensable tool in evaluating antiretroviral therapy (ART) in people living with HIV / AIDS. This study aimed to assess virological suppression among in people living with HIV / AIDS on antiretroviral therapy in Guinea.MethodsThis was a descriptive cross-sectional study of more than three years that involved adult HIV-positive patients treated in different sites in Conakry. A total of 9815 viral load data were collected. The viral load was quantified by the Generic Biocentric technique and the detection threshold set at 350 copies/ml. Statistical analyses were performed by R software version R4.0.3..ResultsA total of 9815 viral load data collected at the national public health laboratory were analysed. The sample was dominated by women (72%), with an average age of 29 [29, 39]. Of these, 6,706 (68%) of HIV-positive people on ART had viral load suppression. The univaried analysis showed that women were 22% more likely to have VL suppression (p-value <0.001) moreover, the chance for all HIV-positive people on treatment to achieve viral load suppression was related to the length of treatment.Conclusionthe results of this study show viral load suppression greater than 68%. The length of antiretroviral therapy, female gender, and advancing age of PLHIV were all favourable to VL suppression.

Modeling HIV-1 Within-Host Dynamics After Passive Infusion of the Broadly Neutralizing Antibody VRC01

VRC01 is a broadly neutralizing antibody that targets the CD4 binding site of HIV-1 gp120. Passive administration of VRC01 in humans has assessed the safety and the effect on plasma viremia of this monoclonal antibody (mAb) in a phase 1 clinical trial. After VRC01 infusion, the plasma viral load in most of the participants was reduced but had particular dynamics not observed during antiretroviral therapy. In this paper, we introduce different mathematical models to explain the observed dynamics and fit them to the plasma viral load data. Based on the fitting results we argue that a model containing reversible Ab binding to virions and clearance of virus-VRC01 complexes by a two-step process that includes (1) saturable capture followed by (2) internalization/degradation by phagocytes, best explains the data. This model predicts that VRC01 may enhance the clearance of Ab-virus complexes, explaining the initial viral decay observed immediately after antibody infusion in some participants. Because Ab-virus complexes are assumed to be unable to infect cells, i.e., contain neutralized virus, the model predicts a longer-term viral decay consistent with that observed in the VRC01 treated participants. By assuming a homogeneous viral population sensitive to VRC01, the model provides good fits to all of the participant data. However, the fits are improved by assuming that there were two populations of virus, one more susceptible to antibody-mediated neutralization than the other.

Vaccinated and unvaccinated individuals have similar viral loads in communities with a high prevalence of the SARS-CoV-2 delta variant

SARS-CoV-2 variant B.1.617.2 (delta) is associated with higher viral loads [1] and increased transmissibility relative to other variants, as well as partial escape from polyclonal and monoclonal antibodies [2]. The emergence of the delta variant has been associated with increasing case counts and test-positivity rates, indicative of rapid community spread. Since early July 2021, SARS-CoV-2 cases in the United States have increased coincident with delta SARS-CoV-2 becoming the predominant lineage nationwide [3]. Understanding how and why the virus is spreading in settings where there is high vaccine coverage has important public health implications. It is particularly important to assess whether vaccinated individuals who become infected can transmit SARS-CoV-2 to others. In Wisconsin, a large local contract laboratory provides SARS-CoV-2 testing for multiple local health departments, providing a single standard source of data using the same assay to measure virus burdens in test-positive cases. This includes providing high-volume testing in Dane County, a county with extremely high vaccine coverage. These PCR-based tests provide semi-quantitative information about the viral load, or amount of SARS-CoV-2 RNA, in respiratory specimens. Here we use this viral load data to compare the amount of SARS-CoV-2 present in test-positive specimens from people who self-report their vaccine status and date of final immunization, during a period in which the delta variant became the predominant circulating variant in Wisconsin. We find no difference in viral loads when comparing unvaccinated individuals to those who have vaccine "breakthrough" infections. Furthermore, individuals with vaccine breakthrough infections frequently test positive with viral loads consistent with the ability to shed infectious viruses. Our results, while preliminary, suggest that if vaccinated individuals become infected with the delta variant, they may be sources of SARS-CoV-2 transmission to others.

RHIVDB: A Freely Accessible Database of HIV Amino Acid Sequences and Clinical Data of Infected Patients

Human immunodeficiency virus (HIV) infection remains one of the most severe problems for humanity, particularly due to the development of HIV resistance. To evaluate an association between viral sequence data and drug combinations and to estimate an effect of a particular drug combination on the treatment results, collection of the most representative drug combinations used to cure HIV and the biological data on amino acid sequences of HIV proteins is essential. We have created a new, freely available web database containing 1,651 amino acid sequences of HIV structural proteins [reverse transcriptase (RT), protease (PR), integrase (IN), and envelope protein (ENV)], treatment history information, and CD4+ cell count and viral load data available by the user’s query. Additionally, the biological data on new HIV sequences and treatment data can be stored in the database by any user followed by an expert’s verification. The database is available on the web at http://www.way2drug.com/rhivdb.

Detecting SARS-CoV-2 by Realtime RT-PCR in clinical samples collected in the North of Vietnam

From January to August 2020, Northern Viet Nam faced a COVID-19 outbreak, up to September 2020, there were 1122 confrmed cases of SARS-CoV-2, of which 465 cases were imported from Europe, America and Asia, 657 cases were identifed domestically. A total of 30,686 samples were collected during the SARS-CoV-2 outbreak in Northern Viet Nam and examined by Real-time RT-PCR using primers and probe from Charite - Berlin protocol. This study showed the initial results of SARS-CoV-2 detection and RNA quantitative in positive samples. The positive rate was 0.8%, ranging from 0.4 to 3.5% according to collection sites. Out of 251 positive samples, the mean Ct value was 28 (IQR: 22.3-32; range 14 - 38). The positive samples had a Ct value below 30 was 68.5%, there was no signifcant difference between the Ct value of the group ≤ 30 and > 30. The mean of the RNA copies/µl was 8.4.107, (IQR: 2.29.106 - 1.83.109 RNA copies/µl, range: 1.95.103 – 4.95.1011). In the group of imported COVID-19 cases, the rate of virus at low level was 29%, an average was 56% and at high level was 15%. In the community groups, the viral load data showed that the average rate at low, intermediate and high level were 20%, 63% and 17% respectively. The proportion of high-level viral load may raise an alert to start the quarantine process to reduce the transmission of SARS-CoV-2

The efficacy of first-line ART regimens based on RPV in HIV-infected patients with pre-existing E138A mutation in reverse transcriptase

Introduction It was previously shown that the presence of the E138A mutation is associated with resistance to rilpivirine (RPV). Detection of this mutation is considered as contraindication for RPV use within the first-line ART. It is a lack of knowledge regarding efficacy of first-line RPV-based ART in patients bearing HIV with E138A mutation. In absence of HIV genotyping in naïve patients it may influence the clinical decisions.Methods We have collected all available patients unconventionally treated with RPV and carefully analyzed the ART efficacy in E138A carriers from the EuResist database. The viral load data in patients with E138A mutation at baseline was extracted from the database. Due to uniqueness of these cases only 11 HIV infected patients were found. The virologic outcome was analyzed according to the national and international ART guidelines.Results The full virologic efficacy of the first-line RPV-based ART regimen was demonstrated in 11 out of 11 patients according to all guidelines.Conclusions Our data suggest that the influence of the pre-existing E138A mutation on the sensitivity to RPV is very low or insignificant. The results support importance of investigation of polymorphic pre-existing HIV drug mutations for ART efficacy.

Optimal design for phase 2 studies of SARS-CoV-2 antiviral drugs

There is no agreed methodology for pharmacometric assessment of candidate antiviral drugs in COVID-19. The most widely used measure of virological response in clinical trials so far is the time to viral clearance assessed by qPCR of viral nucleic acid in eluates from serial nasopharyngeal swabs. We posited that the rate of viral clearance would have better discriminatory value. Using a pharmacodynamic model fit to individual SARS-CoV-2 virus clearance data from 46 uncomplicated COVID-19 infections in a cohort of prospectively followed adults, we simulated qPCR viral load data to compare type 2 errors when using time to clearance and rate of clearance under varying antiviral effects, sample sizes, sampling frequencies and durations of follow-up. The rate of viral clearance is a uniformly superior endpoint as compared to time to clearance with respect to type 2 error, and it is not dependent on initial viral load or assay sensitivity. For greatest efficiency pharmacometric assessments should be conducted in early illness and daily qPCR samples should be taken over 7 to 10 days in each patient studied. Adaptive randomisation and early stopping for success permits more rapid identification of active interventions.

Misinterpretation of viral load in COVID-19

Knowledge of viral load is essential for formulating strategies for antiviral treatment, vaccination, and epidemiological control of COVID-19. Moreover, patients identification with high viral load could also be useful to understand risk factors such as age, comorbidities, severity of symptoms and hypoxia to decide the need for hospitalization. Several studies are evaluating the importance of analyzing viral load in different types of samples, clinical outcomes and viral transmission pathways. However, in a great number of emerging studies cycle threshold (Ct) values by itself is often used as a viral load indicator, which may be a mistake. In this study, we compared tracheal aspirate with nasopharyngeal samples obtained from critically ill COVID-19 patients and demonstrate how the raw Ct could lead to misinterpretation of results. Further, we analyzed nasopharyngeal swabs positive samples and propose a method to reduce evaluation error that could occur from using raw Ct. Based on these findings, we show the impact that normalization of Ct values has on interpretation of viral load data from different biological samples from patients with COVID-19, transmission and lastly in relations with clinical outcomes.ImportanceIn a pandemic, prevention of disease transmission is key. Reliable data for profiles of viral load are needed and important to guide antiviral treatment, infection control and vaccination. The differential expression of SARS-CoV-2 viral RNA among patient groups is a current topic of interest and viral load has been associated with a diversity of outcomes. However, in a great number of emerging studies cycle threshold (Ct) values by itself is often used as a viral load indicator, which may be a mistake. In this study, we compared tracheal aspirate with nasopharyngeal samples obtained from critically ill COVID-19 patients and demonstrate how the raw Ct could lead to misinterpretation of results. Based on these findings, we show the impact that normalization of Ct values has on interpretation of viral load data from different biological samples from patients with COVID-19, transmission and lastly in relations with clinical outcomes.