Enteric viruses replicate in salivary glands and infect through saliva.

Enteric viruses like norovirus, rotavirus and astrovirus have long been accepted as spreading in the population through fecal-oral transmission: viruses are shed into feces from one host and enter the oral cavity of another, bypassing salivary glands (SGs) and reaching the intestines to replicate, be shed in feces and repeat the transmission cycle1. Yet there are viruses (for example, rabies) that infect the SGs2,3, making the oral cavity one site of replication and saliva one conduit of transmission. Here we report that enteric viruses productively and persistently infect SGs, reaching titres comparable to those in the intestines. We demonstrate that enteric viruses get released into the saliva, identifying a second route of viral transmission. This is particularly significant for infected infants, whose saliva directly transmits enteric viruses to their mothers' mammary glands through backflow during suckling. This sidesteps the conventional gut-mammary axis route4 and leads to a rapid surge in maternal milk secretory IgA antibodies5,6. Lastly, we show that SG-derived spheroids7 and cell lines8 can replicate and propagate enteric viruses, generating a scalable and manageable system of production. Collectively, our research uncovers a new transmission route for enteric viruses with implications for therapeutics, diagnostics and importantly sanitation measures to prevent spread through saliva.

Bridging the Gap in Harm Reduction Using Mobile Overdose Response Services (MORS) in the Context of the COVID-19 Pandemic: A Qualitative Study.

The COVID-19 pandemic introduced additional health challenges for people who use substances (PWUS) amid the overdose crisis. Numerous harm reduction services, including supervised consumption sites (SCS) across Canada, faced shutdowns and reduced operating capacity in order to comply with public health measures. Mobile Overdose Response Services (MORS) are novel overdose prevention technologies that allow those who are unable to access alternative means of harm reduction to consume substances under the virtual supervision of a trained operator. Here, we examine the role of MORS in the context of the COVID-19 pandemic. A total of 59 semi-structured interviews were conducted with the following key interest groups: PWUS, healthcare providers, harm reduction workers, MORS operators, and the general public. Inductive thematic analysis informed by grounded theory was used to identify major themes pertaining to the perception of MORS. As the pandemic shifted the public focus away from harm reduction, many participants viewed MORS as an acceptable strategy to reduce the harms associated with solitary substance and alleviate the sense of isolation driven by social distancing measures. While the pandemic may have increased the utility of MORS, concerns surrounding personal privacy and confidentiality remained. Overall, MORS were perceived as a useful adjunct service to address the unmet needs PWUS during the pandemic and beyond.

Preference for hotline versus mobile application/countdown-based mobile overdose response services: a qualitative study.

BACKGROUND: In response to the exacerbated rates of morbidity and mortality associated with the overlapping overdose and COVID-19 epidemics, novel strategies have been developed, implemented, operationalized and scaled to reduce the harms resulting from this crisis. Since the emergence of mobile overdose response services (MORS), two strategies have aimed to help reduce the mortality associated with acute overdose including staffed hotline-based services and unstaffed timer-based services. In this article, we aim to gather the perspectives of various key interest groups on these technologies to determine which might best support service users. METHODS: Forty-seven participants from various interested groups including people who use substances who have and have not used MORS, healthcare workers, family members, harm reduction employees and MORS operators participated in semi-structured interviews. Transcripts were coded and analyzed using a thematic analysis approach. RESULTS: Four major themes emerged regarding participant perspectives on the differences between services, namely differences in connection, perceived safety, privacy and accessibility, alongside features that are recommended for MORS in the future. CONCLUSIONS: Overall, participants noted that individuals who use substances vary in their desire for connection during a substance use session offered by hotline and timer-based service modalities. Participants perceived hotline-based approaches to be more reliable and thus potentially safer than their timer-based counterparts but noted that access to technology is a limitation of both approaches.

Implementing Canada's first national virtual phone based overdose prevention service: lessons learned from creating the National Overdose Response Service (NORS).

The opioid epidemic remains one of the largest public health crises in North America to date. While there have been many diverse strategies developed to reduce the harms associated with substance use, these are primarily concentrated within a few large urban centers. As a result, there have been increased calls for equitable access to harm reduction services for those who cannot or choose not to access in-person harm reduction services. In December 2020, Canada's National Overdose Response Service (NORS) a telephone based overdose response hotline and virtual supervised consumption service, was established in collaboration with various agencies and people with lived and living experience of substance use (PWLLE) across Canada to expand access to harm reduction services using novel Opioid Response Technology. In this manuscript we explore the lessons learned from the establishment and continued operation of the service exploring topics related to the initial establishment of the service, securing a phone line, routing technology, EMS dispatch solutions, peer and volunteer recruitment, legal and ethical support, policy and procedure development, securing funding, and marketing. Furthermore, we detail how this service has grown and changed in response to the various needs of service users.

Understanding the barriers and facilitators to implementing and sustaining Mobile Overdose Response Services from the perspective of Canadian key interest groups: a qualitative study.

INTRODUCTION: Unregulated supply of fentanyl and adulterants continues to drive the overdose crisis. Mobile Overdose Response Services (MORS) are novel technologies that offer virtual supervised consumption to minimize the risk of fatal overdose for those who are unable to access other forms of harm reduction. However, as newly implemented services, they are also faced with numerous limitations. The aim of this study was to examine the facilitators and barriers to the adoption of MORS in Canada. METHODS: A total of 64 semi-structured interviews were conducted between November 2021 and April 2022. Participants consisted of people who use substances (PWUS), family members of PWUS, health care professionals, harm reduction workers, MORS operators, and members of the general public. Inductive thematic analysis was used to identify the major themes and subthemes. RESULTS: Respondents revealed that MORS facilitated a safe, anonymous, and nonjudgmental environment for PWUS to seek harm reduction and other necessary support. It also created a new sense of purpose for operators to positively contribute to the community. Further advertising and promotional efforts were deemed important to increase its awareness. However, barriers to MORS implementation included concerns regarding privacy/confidentiality, uncertainty of funding, and compassion fatigue among the operators. CONCLUSION: Although MORS were generally viewed as a useful addition to the currently existing harm reduction services, it's important to monitor and tackle these barriers by engaging the perspectives of key interest groups.

Prescribing safe supply: ethical considerations for clinicians.

The COVID-19 pandemic has exacerbated the drug poisoning epidemic in a number of ways: individuals use alone more often, there is decreased access to harm reduction services and there has been an increase in the toxicity of the unregulated drug supply. In response to the crisis, clinicians, policy makers and people who use drugs have been seeking ways to prevent the worst harms of unregulated opioid use. One prominent idea is safe supply. One form of safe supply enlists clinicians to prescribe opioids so that people have access to drugs of known composition and strength. In this paper, we assess the ethical case for clinicians providing this service. As we describe, there is much that is unknown about safe supply. However, given the seriousness of the overdose death epidemic and the current limited evidence for safe supply's efficacy, we argue that it is ethically permissible for clinicians to begin prescribing opioids for some select patients.

Association of drug overdoses and user characteristics of Canada's national mobile/virtual overdose response hotline: the National Overdose Response Service (NORS).

BACKGROUND: Several novel overdose response technology interventions, also known as mobile overdose response services (MORS), have emerged as adjunct measures to reduce the harms associated with the drug poisoning epidemic. This retrospective observational study aims to identify the characteristics and outcomes of individuals utilizing one such service, the National Overdose Response Service (NORS). METHODS: A retrospective analysis was conducted using NORS call logs from December 2020 to April 2023 imputed by operators. A variety of variables were examined including demographics, substance use and route, location, and call outcomes. Odds ratios and 95% confidence intervals were calculated around variables of interest to test the association between key indicators and drug poisonings. RESULTS: Of the 6528 completed calls on the line, 3994 (61.2%) were for supervised drug consumption, 1703 (26.1%) were for mental health support, 354 (5.42%) were for harm reduction education or resources, and 477 (7.31%) were for other purposes. Overall, there were 77 (1.18%) overdose events requiring a physical/ in-person intervention. Of the total calls, 3235 (49.5%) were from women, and 1070 (16.3%) were from people who identified as gender diverse. Calls mostly originated from urban locations (n = 5796, 88.7%) and the province of Ontario (n = 4137, 63.3%). Odds ratios indicate that using opioids (OR 6.72, CI 95% 3.69-13.52), opioids in combination with methamphetamine (OR 9.70, CI 95% 3.24-23.06), multiple consumption routes (OR 6.54, CI 95% 2.46-14.37), and calls occurring in British Columbia (B.C) (OR 3.55, CI 95% 1.46-7.33) had a significantly higher likelihood of a drug poisoning. No deaths were recorded and only 3 false callouts had occurred. The overall drug poisoning event incidence to phone calls was 1.2%. CONCLUSION: NORS presents a complimentary opportunity to access harm reduction services for individuals that prefer to use alone or face barriers to accessing in-person supervised consumption services especially gender minorities with high-risk use patterns.

Investigating uses of peer-operated Virtual Overdose Monitoring Services (VOMS) beyond overdose response: a qualitative study.

Background: Virtual overdose monitoring services (VOMS) are novel technologies that allow remote monitoring of individuals while they use substances (especially those who use alone) electronically.Objectives: The authors explored key partner perspectives regarding services offered by VOMS beyond overdose response with the aim of understanding the breadth and perception of the services amongst those that use these services and are impacted by them.Methods: Forty-seven participants from six key partner groups [peers who had used VOMS (25%), peers who had not used VOMS (17%), family members of peers (11%), health professionals (21%), harm reduction sector employees (15%), and VOMS operators (15%)] underwent 20-to-60-minute semi-structured telephone interviews. Of peer and family groups, thirteen participants identified as female, eleven as male and one as non-binary, gender data was not recorded for other key partner groups. Interview guides were developed and interviews were conducted until saturation was reached across all participants. Themes and subthemes were identified and member checked with partner groups.Results: Participants indicated that uses of VOMS beyond overdose monitoring included: (1) providing mental health support and community referral; (2) methamphetamine agitation de-escalation; (3) advice on self-care and harm reduction; and (4) a sense of community and peer support. Respondents were divided on how VOMS might affect emergency services (5).Conclusions: VOMS are currently being used for purposes beyond drug poisoning prevention, including community methamphetamine psychosis de-escalation, mental health support, and community peer support. VOMS are capable of delivering a broad suite of harm reduction services and referring clients to recovery-oriented services.

Feasibility and acceptability of inserts promoting virtual overdose monitoring services (VOMS) in naloxone kits: a qualitative study.

BACKGROUND: In response to the ongoing opioid epidemic, there have been efforts to develop novel harm reduction strategies alongside scaling of currently implemented programs. Virtual overdose monitoring services (VOMS) are a novel intervention which aims to reduce substance-related mortality through technology for those who are out of reach of current supervised consumption sites. Scaling of naloxone programs presents a unique opportunity to promote VOMS to people at risk of substance-related mortality. This study aims to explore the feasibility and acceptability of naloxone kit inserts in promoting awareness of VOMS. METHOD: We used purposive and snowball sampling to recruit 52 key informants, including people who use drugs (PWUD) with experience using VOMS (n = 16), PWUD with no prior experience using VOMS (n = 9), family members of PWUD (n = 5), healthcare and emergency services professionals (n = 10), community-based harm reduction organizations (n = 6), and VOMS administrators/peer support workers (n = 6). Two evaluators completed semi-structured interviews. Interview transcripts were analyzed using thematic analysis informed to identify key themes. RESULTS: Four key interrelated themes emerged, including the acceptability of naloxone kit inserts to promote VOMS, best practices for implementation, key messaging to include within promotional materials and facilitators to dissemination of harm reduction material. Participants highlighted that messaging should be promoted both inside and outside the kits, should be concise, provide basic information about VOMS and can be facilitated through current distribution streams. Messaging could further be used to draw attention to local harm reduction services and could be promoted on other supplies, including lighters and safer consumption supplies. CONCLUSION: Findings demonstrate that it is acceptable to promote VOMS within naloxone kits and highlight interviewees preferred ways to do so. Key themes that emerged from interviewees can be used to inform the dissemination of harm reduction information, including VOMS and bolster current strategies for reducing illicit drug overdose.

Beliefs, attitudes and experiences of virtual overdose monitoring services from the perspectives of people who use substances in Canada: a qualitative study.

BACKGROUND: Solitary use of substances is a risk factor for substance use-related mortality. Novel e-health harm reduction interventions such as virtual overdose monitoring services (VOMS) have emerged in North America to improve access to emergency overdose support for people who use substances (PWUS). To date, little research has been published, and the perspectives of PWUS are needed to inform evaluation and policy efforts. OBJECTIVE: To explore the beliefs, values and perceptions of PWUS around using and accessing VOMS in Canada. METHODS: A qualitative study following grounded theory methodology was conducted. Using existing peer networks, purposive and snowball sampling was conducted to recruit PWUS (≥ 18 years) with previous experience with VOMS. Thematic analysis was used to analyze twenty-three interviews. Several methods were employed to enhance rigor, such as independent data coding and triangulation. RESULTS: Twenty-three one-on-one telephone interviews of PWUS with previous experience with VOMS were completed and analyzed. The following themes emerged: (1) feelings of optimism around VOMS to save lives; (2) privacy/confidentiality was highly valued due to stigma and fear of arrest; (3) concerns with reliable cell phones negatively impacting VOMS uptake; (4) concerns around emergency response times, specifically in rural/remote communities; (5) desire for trusting relationships with VOMS operators; (6) importance of mental health supports and referrals to psychosocial services; and (7) possible limited uptake due to low public awareness of VOMS. CONCLUSION: This qualitative study provided novel insights about the VOMS from the perspectives of PWUS. PWUS generally felt optimistic about the potential of VOMS as a suitable harm reduction intervention, but several potential barriers around accessing VOMS were identified that may limit uptake. Future research is warranted.

Genome-wide DNA methylation profiling of stomach cancer in the ethnic population of Mizoram, North East India.

Stomach cancer is the fifth most common cancer in terms of prevalence and incidence and the fourth leading cause of mortality in men and women worldwide. It is well-established that aberrant DNA methylation in cells can lead to carcinogenesis. The primary objective of our study was to investigate the aberrant DNA methylation status of genes associated with stomach cancer with a particular reference to the ethnic population of Mizoram, North East India. The site-level analysis identified 2883 CpG sites differentially methylated, representing ∼922 genes. Out of which 476 Differentially Methylated Positions (DMPs) were promoter-associated, 452 DMPs were hypermethylated, and 24 were hypomethylated. The region-level analysis identified 462 Differentially Methylated Regions (DMRs) corresponding to ∼320 genes, of which ∼281 genes were hypermethylated and âˆ¼40 genes were hypomethylated. TCGA analysis showed that some of the genes had been previously implicated in other cancers including stomach cancer. Five hypermethylated genes were selected as candidate genes for further investigations and they have shown to be novel and could serve as candidate hypermethylation biomarkers for stomach cancer in this particular ethnic group.

Resonant Annihilation and Positron Bound States in Benzene.

Positrons attach to molecules in vibrationally resonant two-body collisions that result in greatly enhanced annihilation rates. Measurements of annihilation as a function of positron energy are presented for benzene using a cryogenic, trap-based beam. They establish a positron binding energy of 132±3 meV to test state-of-the-art theoretical calculations, and they exhibit many unexpected resonances, likely due to combination and overtone vibrational modes. The relationship of these results to the unique π-bonded structure of benzene is discussed.

Spatial Properties of Entangled Two-Photon Absorption.

We experimentally study entangled two-photon absorption in rhodamine 6G as a function of the spatial properties of a high flux of broadband entangled photon pairs. We first demonstrate a key signature dependence of the entangled two-photon absorption rate on the type of entangled pair flux attenuation: linear, when the laser pump power is attenuated, and quadratic, when the pair flux itself experiences linear loss. We then perform a fluorescence-based Z-scan measurement to study the influence of beam waist size on the entangled two-photon absorption process and compare this to classical single- and two-photon absorption processes. We demonstrate that the entangled two-photon absorption shares a beam waist dependence similar to that of classical two-photon absorption. This result presents an additional argument for the wide range of contrasting values of quoted entangled two-photon absorption cross sections of dyes in literature.

Impact of baseline body mass index on the outcomes of patients with neuroendocrine neoplasms.

OBJECTIVE: To assess the impact of baseline body mass index (BMI) on the outcomes of patients with neuroendocrine neoplasms (NENs) in a population-based setting. METHODS: Linked provincial administrative databases (within the province of Alberta, Canada), 2004-2019, were accessed, and patients with NENs and complete information about BMI near the time of diagnosis were reviewed. The impact of BMI on overall survival was evaluated through the use of Kaplan-Meier survival estimates and multivariable Cox regression modeling. RESULTS: A total of 1010 patients with NENs and BMI information were included. Using Kaplan-Meier survival estimates, survival outcomes were best with individuals with obesity and were worst with underweight individuals (P < 0.0001). The following factors were associated with worse overall survival, older age (HR: 1.02; 95% CI: 1.01-1.03), male sex (HR: 1.60; 95% CI: 1.32-1.93), higher Charlson comorbidity index (HR: 1.22; 95% CI: 1.13-1.31), non-small intestinal primary (HR for gastric primary versus small intestinal primary: 2.36; 95% CI: 1.44-3.85), stage 4 disease (HR: 2.67; 95% CI: 2.16-3.31), neuroendocrine carcinoma histology (HR: 1.76; 95% CI: 1.43-2.17), and underweight BMI (HR versus normal BMI: 1.74; 95% CI: 1.11-2.73). When the model was repeated using BMI as a continuous variable (rather than as a categorical variable), increasing BMI was associated with better overall survival (HR with increasing BMI: 0.97; 95% CI: 0.95-0.98). CONCLUSIONS: Lower BMI is associated with worse overall survival among patients with NENs. This finding was demonstrable regardless of the tumor's stage or histology.

Effect of endogenous hormones, antisperm antibody and oxidative stress on semen quality of crossbred bulls.

The present study was designed to evaluate the effect of factors like hormones, antisperm antibody (ASA), and oxidative stress and its relation with semen quality in crossbred bulls. Ejaculates from two bulls were categorized into good (n = 12) and poor (n = 12) based on initial progressive motility, that is, ≥70% and ≤50%, respectively. The level of hormones like Testosterone (p < 0.05) and PGE2 (p < 0.01) was significantly higher in good-quality ejaculates compared to poor-quality ejaculates; however, estradiol (p < 0.05), progesterone, oxidative stress, and ASAs were significantly higher (p < 0.01) in poor-quality ejaculates compared to good-quality ejaculates. Therefore, it could be concluded that oxidative stress and hormonal imbalance might have resulted in high number of dead and defective spermatozoa which was ultimately responsible for poor quality semen ejaculates.

Correlation between dissolved oxygen level, antioxidants and oxidants in semen diluted with partially deoxygenated extender at various stages of cryopreservation.

BACKGROUND: Dissolved oxygen (DO) in semen dilutor may lead to the production of reactive oxygen species (ROS) and buffalo sperm may become more prone to deleterious effects of ROS due to the presence of high amounts of polyunsaturated fatty acids (PUFAs) in their membranes. OBJECTIVE: To study the correlation between dissolved oxygen level, antioxidants and oxidants in semen diluted with partially deoxygenated extender at various stages of cryopreservation. MATERIALS AND METHODS: Each semen sample was split into two aliquots viz., Aliquot I [diluted with Extender I (control: without deoxygenation)] and Aliquot II [diluted with Extender II: partially deoxygenated by liquid nitrogen (LN) flushing], which were diluted, filled in straws, cryopreserved and evaluated post-thaw. RESULTS: The DO levels (P < 0.05) decreased significantly after LN flushing of the extender and they increased significantly (P < 0.05) in post-thaw semen. The progressive motility, viability, hypo-osmotic swelling response, acrosomal integrity, glutathione peroxidase (GPx), total antioxidant capacity (TAC) and superoxide dismutase (SOD) decreased significantly (P < 0.05) in both control and treated semen after thawing. SOD and TAC were positively correlated in semen treated with normal extender at the pre-freeze stage; however, in semen treated with partially deoxygenated extender, no correlation was found between SOD and TAC at the pre-freeze stage. ROS and total TAC were negatively correlated in semen treated with partially deoxygenated extender at the pre-freeze stage; however, no correlation was found between ROS and TAC in control semen. CONCLUSION: The partial deoxygenation of extender affects the correlation between sperm quality parameters, antioxidants, and oxidants during different stages of semen cryopreservation. doi.org/10.54680/fr22310110712.

Cryoprotectant with a mitochondrial derived peptide, humanin, improves post-thaw quality of buffalo spermatozoa.

BACKGROUND: Semen cryopreservation results in deleterious effects on spermatozoa, including lipid peroxidation and a reduction in the total antioxidant components of seminal plasma. The ultimate outcome of these changes is a reduction in post-thaw semen quality. A mitochondrial derived peptide, humanin, a potent cytoprotective and antioxidant agent was used in the present study. OBJECTIVE: To evaluate the efficacy of a mitochondrial-derived peptide, humanin to improve the post-thaw quality of buffalo spermatozoa. MATERIALS AND METHODS: A total of 18 ejaculates from three Murrah buffalo bulls (n=6 each) were collected. Each ejaculate was divided into four aliquots. The first aliquot was diluted with standard EYTG dilutor (Group I, control), whereas the other three aliquots were diluted with EYTG supplemented with 2 µM (Group II), 5 µM (Group III) and 10 µM humanin (Group IV), respectively. Semen was evaluated for physico-morphological and functional attributes such as progressive motility, viability, abnormality, acrosome integrity, plasmamembrane integrity of fresh samples, pre-freeze and post-thaw stages. Oxidative stress parameters [lipid peroxidation (LPO) and total antioxidant capacity (TAC)] were also measured at the pre-freeze and post-thaw stages. RESULTS: Humanin supplementation resulted in significantly higher (p < 0.05) post-thaw motility in all treatment groups and, higher (p < 0.05) viability in Groups III and IV in comparison to the control at the post-thaw stage. Spermatozoa with intact acrosome and plasma membrane were higher (p < 0.05) in Groups III and IV as compared to Groups I and II. The LPO levels at the post-thaw stage were found to be lower (p < 0.05) in all treatment groups versus the control group, whereas, higher (p≤0.05) TAC values were recorded in Groups III and IV in comparison to the control and Group II. CONCLUSION: Humanin supplementation in the extender improved the freezabilty of buffalo spermatozoa.

Cryoprotection of humanin-like peptides in seminal plasma for ejaculated spermatozoa of crossbred bulls.

BACKGROUND: Cryopreservation process negatively affects spermatozoa functions. Humanin, a small polypeptide encoded in the mitochondrial genome, is well known for its role in cell survival. OBJECTIVE: To quantify the endogenous levels of humanin in seminal plasma of crossbred Frieswal bulls and to study its role in cryoprotection. The presence of humanin in bull spermatozoa was also investigated. MATERIALS AND METHODS: A total of 40 semen samples were separated into two groups based on the initial progressive motility (IPM): Good (IPM >70%) and Poor (IPM <50%) groups; and/or based on the post-thaw motility (PTM): Freezable (PTM>50%) and Non-freezable (PTM < 50%) groups. Humanin concentration in seminal plasma (SP-HN) was quantified using ELISA. RESULTS: SP-HN concentration ranged from undetectable to 67.6 pg/mL with a median level of 35.2 pg/mL. SP-HN level was significantly higher in the good quality semen group than in the poor quality semen group (p<0.001), and also significantly higher in the freezable group than in the non-freezable group (p<0.001). SP-HN level was positively correlated with initial progressive motility, post-thaw semen motility, viability, acrosome intactness and plasma membrane integrity, but negatively correlated the level of reactive oxygen species and malondialdehyde content. Immunochemical localization showed the presence of humanin in the proximal region of the middle piece of spermatozoa. CONCLUSION: Endogenous humanin level had significant correlation with semen quality and might protect sperm cells against freeze-induced oxidative stress. doi.org/10.54680/fr22510110712.

Findings of second multicentric follow-up serosurvey among Health Care Workers in government hospitals.

Background: The change in serological status of community may be used as input for guiding the public health policy. Hence, the present study was conducted to determine change in seroprevalence of COVID-19 among healthcare workers (HCWs). Methods: From the baseline multicentric study sample, a subsample was followed up, and a seroepidemiological study was conducted among them between 6 and 22 weeks after the second dose of the vaccination. Multistage population proportion to size sampling was performed for the selection of subsample of HCWs. The serosurvey was conducted using the enzyme-linked immunosorbent assay-based IgG antibody test (COVID KAVACH). Results: Follow-up serological testing was done in subsample of 1122 participants of original 3253 participants. The mean age of the participants was 34.6 (8.13) years. A total of 300 (26.7%) participants were females. The seroprevalence was 78.52, (95%CI:76-80.1). Among those who were seronegative at initial test, 708 (77.04%) were seroconverted. Those who were not seroconverted (241 (21.5%)) have longer duration from the second dose of the vaccination (93 (31.4) vs. 56 (38.4); p value < 0.001). The COVID-19 infection was significantly associated with seropositive status and being a medical staff was associated with remaining seronegative on follow-up. The higher age (≥50 years) was found to be significantly associated with seroreversion. Conclusion: Four in five HCWs had detectable antibodies. Seroepidemiological studies carry vital information to control the public health response in the course of the pandemic. The study can also further help as a platform to study the seroconversion and effect of vaccination among HCWs for newer variants of SARS-CoV-2.

A novel approach for estimation of aboveground biomass of a carbon-rich mangrove site in India.

Mangroves can play a crucial part in climate change mitigation policies due to their high carbon-storing capacity. However, the carbon sequestration potential of Indian mangroves generally remained unexplored to date. In this study, multi-temporal Sentinel-1 and 2 data-derived variables were used to estimate the AGB of a tropical carbon-rich mangrove forest of India. Ensemble prediction of multiple machine learning algorithms, including Random Forest (RF), Gradient Boosted Model (GBM), and Extreme Gradient Boosting (XGB), were used for AGB prediction. The multi-temporal dataset was used in two different ways to find the most suitable method of using them. The results of the analysis showed that the modeling field measured AGB with individual date data values results in estimates with root mean square errors (RMSE) ranging from 149.242 t/ha for XGB to 151.149 t/ha for the RF. Modeling AGB with the average and percentile metrics of the multi-temporal image stack improves the prediction accuracy of AGB, with RMSE ranging from 81.882 t/ha for the XGB to 74.493 t/ha for the RF. The AGB modeling using ensemble prediction showed further improvement in accuracy with an RMSE of 72.864 t/ha and normalized RMSE of 11.38%. In this study, the intra-seasonal variation of Sentinel-1 and 2 data for mangrove ecosystems was explored for the first time. The variations in remotely sensed variables could be attributed mainly to soil moisture availability and rainfall in the mangrove ecosystem. The efficiency of Sentinel-1 and 2 data-derived variables and ensemble prediction of machine learning models for Indian mangroves were also explored for the first time. The methodologies established in this study can be used in the future for accurate prediction and repeated monitoring of AGB for mangrove ecosystems.