Subsequent Waves Research Articles

Forward numerical investigation of potential tsunami deposits in the South China sea: A case study of Nan'ao Island

The South China Sea (SCS) coastlines are particularly vulnerable to tsunamis due to rapid urbanization and dense infrastructures. However, whether the SCS has experienced ocean-wide tsunamis is still under debate. Some geological records from the offshore islands inside the SCS imply a regional tsunami event may have occurred approximately 1000-yr-ago. We address these questions for the first time using forward numerical simulations in the SCS: what source could be responsible for such deposits, how the deposits were formed and at what conditions do the deposits could be preserved? Here, we assume the validity of the tsunami deposit hypothesis and use the forward model COMCOT-SED to investigate if these tsunami deposits can be linked to potential seismogenic tsunami sources inside the SCS, including megathrust earthquakes (Mw8.8–9.2) from the Manila subduction zone (MSZ) and the 1918 Mw7.5 Nan'ao earthquake from the Littoral Fault Zone (LFZ) in the northern continental shelf of the SCS. We also utilize a reported tsunami deposit from Qing'ao Embayment, Nan'ao Island, China, to exemplify the deposit formation process in a typical barrier-low coastal plain system. Quantitative analysis suggests large earthquakes from the MSZ may account for the reported geological deposits. The full-rupture earthquake scenario could best explain the depositions if such extreme case is geophysically and geologically plausible. If not, earthquakes (∼ Mw 9.0) covering the northern (16–23.5°N) or southern portion (14–19°N) of the MSZ could also be suitable candidates. Such great earthquakes can generate large tsunami waves (>7 m) that inundate the Qing'ao Embayment, transporting sediments and leaving tsunami deposits in low-lying areas. Conversely, tsunamis triggered by nearshore earthquakes in the LFZ cannot cause deposition in Qing'ao Embayment. The barrier-low coastal plain system is well-suited for preserving tsunami deposits, which remain unaltered by subsequent tsunami waves. Our findings offer a quantitative reference for paleo-tsunami research in the SCS and enhance global understanding of the tsunami deposition process in barrier-low coastal plain systems.

Seasonality of California Central Coast Microseisms

ABSTRACT Linear scattering of ocean wave energy at the ocean–continent transition structure causes the primary microseism at a period of 14 s. Subsequent nonlinear wave–wave interactions produce the secondary microseism signal at half the primary microseism period (Longuet-Higgins, 1950; Haubrich et al., 1963). We use three years (2018–2022) of seismic data from an ongoing microarray deployment in the UC Santa Barbara Sedgwick Reserve, situated in the Santa Ynez Valley, to constrain seasonal and long-term microseismic noise characteristics for this portion of California’s central coast. Ancillary buoy data (spectral data, wave height, wind speed and direction) from the National Oceanic and Atmospheric Administration are used to explore the causal relationship between ocean swell and the generation of microseisms. This region is found to exhibit strong seasonality in the primary and secondary microseism bands (0.05–0.1 and 0.1–0.3 Hz, respectively), with much higher noise levels in the winter compared with the summer, especially for the secondary microseism (15.4 dB). We also observe a systematic shift in the peak frequency of the secondary microseism between the winter (∼0.14 Hz) and summer (∼0.20 Hz) months, which may reflect a difference in sources of secondary microseisms between the two seasons. Local buoy wave height and spectral data are well correlated with seismic power spectra during times of incoming storm swell in winter, indicating locally generated microseisms along the central coast during this season.

Comparing magnetic pushing to underwater explosions for flyer acceleration

We present results exploring various methods of aluminum flyer acceleration. One method uses the shock wave generated by underwater electrical explosions of thin foils supplied by a pulse generator with stored energy of ∼4.7 kJ. Utilizing the shock created by an exploding foil, a maximal free flyer velocity of ∼2000 m/s is obtained. This acceleration method is compared to results exploiting only magnetic pushing to accelerate flyers using a common strip-line configuration, resulting in much lower velocities of ∼300 m/s. We also present a modified strip-line configuration, for which a significant increase in the flyer velocity to ∼1200 m/s is measured. Finally, a hybrid strip configuration, incorporating both the effects of magnetic pushing and acceleration by exploding foil and its subsequent shock wave, results in ∼1400 m/s flyer velocity. These experimental results are analyzed by numerical simulations and analytical modeling of the conservation equations of mass and momentum.

Sleep Disorders and Cognitive Aging Among Cognitively Impaired Versus Unimpaired Older Adults.

Sleep disorders often predict or co-occur with cognitive decline. Yet, little is known about how the relationship unfolds among older adults at risk for cognitive decline. To examine the associations of sleep disorders with cognitive decline in older adults with unimpaired cognition or impaired cognition (mild cognitive impairment and dementia). A total of 5,822 participants (Mage = 70) of the National Alzheimer's Coordinating Center database with unimpaired or impaired cognition were followed for 3 subsequent waves. Four types of clinician-diagnosed sleep disorders were reported: sleep apnea, hyposomnia/insomnia, REM sleep behavior disorder, or "other." Cognition over time was measured by the Montreal Cognitive Assessment (MoCA) or an estimate of general cognitive ability (GCA) derived from scores based on 12 neuropsychological tests. Growth curve models were estimated adjusting for covariates. In participants with impaired cognition, baseline sleep apnea was related to better baseline MoCA performance (b = 0.65, 95% confidence interval [95% CI] = [0.07, 1.23]) and less decline in GCA over time (b = 0.06, 95% CI = [0.001, 0.12]). Baseline insomnia was related to better baseline MoCA (b = 1.54, 95% CI = [0.88, 2.21]) and less decline in MoCA over time (b = 0.56, 95% CI = [0.20, 0.92]). Furthermore, having more sleep disorders (across the 4 types) at baseline predicted better baseline MoCA and GCA, and less decline in MoCA and GCA over time. These results were only found in those with impaired cognition and generally consistent when using self-reported symptoms of sleep apnea or insomnia. Participants with sleep disorder diagnoses may have better access to healthcare, which may help maintain cognition through improved sleep.

Phytoplankton blooms and fish kills in Lake Tanganyika related to upwelling and the limnological cycle

Characterizing the processes which cause upwelling in the East African Great Lakes enables prediction of the spatial–temporal variability of phytoplankton blooms and increases in fish abundance or incidence of fish kills. The influence of the southeast trade winds on the limnology of Lake Tanganyika is well known. Upwelling occurs to the south and downwelling to the north from May to September and subsequent upwelling and blooms at the northern end of the lake. However, the influence of the shifts in wind speed and direction after the SE trade winds, including the Northeast trade winds, and any further internal wave driven upwelling requires investigation. Here we use images from remote-sensing during a 12 year period (2003–2014) to illustrate intense phytoplankton blooms at the southeast of Lake Tanganyika in April-May, a period characterized by relaxation of the Northeast trade winds. Phytoplankton blooms progressed around the lake after a massive cyanobacteria bloom at the northern end in September 2018; recent and historical observations and local knowledge show similar patterns. Lake Tanganyika limnological cycle is revised to include four main periods: two trade winds seasons and two inter-monsoon seasons (April-May and September-October) with lake-wide up and downwelling of the thermocline associated with the monsoons, and upwelling associated with subsequent internal waves in the inter-monsoon period which are linked with increased phytoplankton blooms and sometimes also fish kills.

Outcomes comparison between the first and the subsequent SARS-CoV-2 waves - a systematic review and meta-analysis.

In the beginning of the SARS-CoV-2 pandemic, health care professionals dealing with COVID-19 had to rely exclusively on general supportive measures since specific treatments were unknown. The subsequent waves could be faced with new diagnostic and therapeutic tools (e.g., anti-viral medications and vaccines). We performed a meta-analysis and systematic review to compare clinical endpoints between the first and subsequent waves. Three databases were assessed. The primary outcome was in-hospital mortality. The secondary outcomes were intensive care unit (ICU) mortality, ICU length of stay (LOS), acute renal failure, extracorporeal membrane oxygenation (ECMO) implantation, mechanical ventilation time, hospital LOS, systemic thromboembolism, myocarditis and ventilator associated pneumonia. A total of 25 studies with 126,153 patients were included. There was no significant difference for the primary endpoint (OR=0.94, 95% CI 0.83-1.07, p=0.35). The first wave group presented higher rates of ICU LOS (SMD= 0.23, 95% CI 0.11-0.35, p<0.01), acute renal failure (OR=1.71, 95% CI 1.36-2.15, p<0.01) and ECMO implantation (OR=1.64, 95% CI 1.06-2.52, p=0.03). The other endpoints did not show significant differences. The analysis suggests that the first wave group, when compared with the subsequent waves group, presented higher rates of ICU LOS, acute renal failure and ECMO implantation, without significant difference in in-hospital or ICU mortality, mechanical ventilation time, hospital LOS, systemic thromboembolism, myocarditis or ventilator- associated pneumonia.

Astrocyte ensheathment of calyx-forming axons of the auditory brainstem precedes accelerated expression of myelin genes and myelination by oligodendrocytes.

Early postnatal brain development involves complex interactions among maturing neurons and glial cells that drive tissue organization. We previously analyzed gene expression in tissue from the mouse medial nucleus of the trapezoid body (MNTB) during the first postnatal week to study changes that surround rapid growth of the large calyx of Held (CH) nerve terminal. Here, we present genes that show significant changes in gene expression level during the second postnatal week, a developmental timeframe that brackets the onset of airborne sound stimulation and the early stages of myelination. Gene Ontology analysis revealed that many of these genes are related to the myelination process. Further investigation of these genes using a previously published cell type-specific bulk RNA-Seq data set in cortex and our own single-cell RNA-Seq data set in the MNTB revealed enrichment of these genes in the oligodendrocyte lineage (OL) cells. Combining the postnatal day (P)6-P14 microarray gene expression data with the previously published P0-P6 data provided fine temporal resolution to investigate the initiation and subsequent waves of gene expression related to OL cell maturation and the process of myelination. Many genes showed increasing expression levels between P2 and P6 in patterns that reflect OL cell maturation. Correspondingly, the first myelin proteins were detected by P4. Using a complementary, developmental series of electron microscopy 3D image volumes, we analyzed the temporal progression of axon wrapping and myelination in the MNTB. By employing a combination of established ultrastructural criteria to classify reconstructed early postnatal glial cells in the 3D volumes, we demonstrated for the first time that astrocytes within the mouse MNTB extensively wrap the axons of the growing CH terminal prior to OL cell wrapping and compaction of myelin. Our data revealed significant expression of several myelin genes and enrichment of multiple genes associated with lipid metabolism in astrocytes, which may subserve axon wrapping in addition to myelin formation. The transition from axon wrapping by astrocytes to OL cells occurs rapidly between P4 and P9 and identifies a potential new role of astrocytes in priming calyceal axons for subsequent myelination.

Cognitive aging and experience of playing a musical instrument.

Musical instrument training has been found to be associated with higher cognitive performance in older age. However, it is not clear whether this association reflects a reduced rate of cognitive decline in older age (differential preservation), and/or the persistence of cognitive advantages associated with childhood musical training (preserved differentiation). It is also unclear whether this association is consistent across different cognitive domains. Our sample included 420 participants from the Lothian Birth Cohort 1936. Between ages 70 and 82, participants had completed the same 13 cognitive tests (every 3 years), measuring the cognitive domains of verbal ability, verbal memory, processing speed, and visuospatial ability. At age 82, participants reported their lifetime musical experiences; 40% had played a musical instrument, mostly in childhood and adolescence. In minimally adjusted models, participants with greater experience playing a musical instrument tended to perform better across each cognitive domain at age 70 and this association persisted at subsequent waves up to age 82. After controlling for additional covariates (childhood cognitive ability, years of education, socioeconomic status, and health variables), only associations with processing speed (β = 0.131, p = .044) and visuospatial ability (β = 0.154, p = .008) remained statistically significant. Participants with different amounts of experience playing a musical instrument showed similar rates of decline across each cognitive domain between ages 70 and 82. These results suggest a preserved differentiation effect: Cognitive advantages (in processing speed and visuospatial ability) associated with experience playing a musical instrument (mostly earlier in life) are preserved during older age. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Evaluation of the relative importance of preheat from hohlraum x rays and a radiative shock on a low-density foam

Indirectly driven shock-tube experiments were performed on the Omega Laser Facility to evaluate the relative importance of hohlraum x ray and radiative shock preheat sources on a low-density foam. X rays emitted from the hohlraum and a subsequent shock wave are channeled into a low-density foam sample, which contains a plastic preheat-witness disk placed downstream of the foam. Simultaneous radiographic measurements of the shock speed in the foam and the expansion rate of the witness disk due to preheat allow for the observation of effects from the hohlraum's low-energy and high-energy x-ray spectrum. We showed, from simulations, that low-energy x rays from the hohlraum are preferentially absorbed near the ablator surface (where the hohlraum and the shock tube meet), while higher-energy x rays largely pass through the ablator and foam and are volumetrically absorbed by the witness disk. Reproducing the experimentally measured shock speed and expansion of the witness disk simultaneously, we extracted the temperature evolution of preheated foam from the simulation and evaluated the relative importance of preheat sources on a low-density foam from hohlraum x-ray radiation and radiative shock. We found that radiation from the shock front was more effective at preheating the low-density foam than the high-energy x rays from the hohlraum. This shock-tube preheat experiment is important for understanding the results of the MARBLE experiments at the National Ignition Facility because initial conditions of foam-filled MARBLE capsules are sensitive to preheat.

RAGE engagement by SARS-CoV-2 enables monocyte infection and underlies COVID-19 severity

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has fueled the COVID-19 pandemic with its enduring medical and socioeconomic challenges because of subsequent waves and long-term consequences of great concern. Here, we chart the molecular basis of COVID-19 pathogenesis by analyzing patients' immune responses at single-cell resolution across disease course and severity. This approach confirms cell subpopulation-specific dysregulation in COVID-19 across disease course and severity and identifies a severity-associated activation of the receptor for advanced glycation endproducts (RAGE) pathway in monocytes. Invitro THP1-based experiments indicate that monocytes bind the SARS-CoV-2 S1-receptor binding domain (RBD) via RAGE, pointing to RAGE-Spike interaction enabling monocyte infection. Thus, our results demonstrate that RAGE is a functional receptor of SARS-CoV-2 contributing to COVID-19 severity.

Changes in mobility patterns during the COVID-19 pandemic in Zambia: Implications for the effectiveness of NPIs in Sub-Saharan Africa.

The COVID-19 pandemic has impacted many facets of human behavior, including human mobility partially driven by the implementation of non-pharmaceutical interventions (NPIs) such as stay at home orders, travel restrictions, and workplace and school closures. Given the importance of human mobility in the transmission of SARS-CoV-2, there have been an increase in analyses of mobility data to understand the COVID-19 pandemic to date. However, despite an abundance of these analyses, few have focused on Sub-Saharan Africa (SSA). Here, we use mobile phone calling data to provide a spatially refined analysis of sub-national human mobility patterns during the COVID-19 pandemic from March 2020-July 2021 in Zambia using transmission and mobility models. Overall, among highly trafficked intra-province routes, mobility decreased up to 52% during the time of the strictest NPIs (March-May 2020) compared to baseline. However, despite dips in mobility during the first wave of COVID-19 cases, mobility returned to baseline levels and did not drop again suggesting COVID-19 cases did not influence mobility in subsequent waves.

The making of the Homo Polaris: human acclimatization to the Arctic environment and Soviet ideologies in Northern Medical Institutions

ABSTRACT This paper examines the history of the Soviet human acclimatization project in the North and Siberia, which spanned from medical experiments in Stalin’s forced labor camps to the subsequent wave of industrialization in the region. The author argues that human acclimatization in the North was a settler colonial science project aimed at facilitating Russian administrators and engineers in asserting control over the territory and its resources, while creating a new homogeneous ‘indigenous population’ in Siberia and the North. This envisioned population, referred to as Homo Polaris by the author, was intended to emerge through a two-way transformation: the adaptation of Indigenous peoples into Soviet ideologies and practices, and the acclimatization of settlers coming from the European part of the country to the Arctic environment. Although the administrators and medical doctors were unable to achieve this biopolitical objective, the complexities and dialogues surrounding these transformations shed light on the late Soviet settler-colonial ideologies and their impact on social life in Siberia from the 1950s to the 1980s. The research is based on a comprehensive analysis of both published and archival works by scholars involved in the project.

Evaluation of blast wave from hydrogen pipeline burst by a coupled fluid-structure-rupture approach

Coupled fluid-structure-rupture model was developed to evaluate the blast field from X65 hydrogen pipeline burst. Johnson-Cook material model was implemented considering the high strain rates of material at crack tips. Internal hydrogen decompression, outer blast wave generation and propagation, and dynamic rupture of pipeline were simulated simultaneously and validated with experiments. Results demonstrated that the crack primarily ran axially at an average speed of about 120 m/s, while the maximum speed was about 200 m/s. Due to the dynamic growth of rupture opening, the outer blast wave experienced a process of first form and then strengthened by subsequent compression waves. This makes the maximum peak overpressure along the jetting direction appears at a certain standoff distance above rupture. The blast overpressures along the jetting direction were compared and discussed with those from traditional CFD method, TNT equivalence method and Baker-Tang blast curves. It was found the effective volume to calculate the burst energy needs to be further studied. Also, new blast curves were required for quick and rational estimation of blast overpressure from hydrogen pipeline burst.

Blame‐avoidance and fragmented crisis management during the COVID‐19 pandemic in Switzerland

AbstractThis article studies how the prolonged pandemic situation impacted crisis governance in the federalized governance system of Switzerland. It examines how in this acute crisis situation, the responsibility for decision‐making fluctuated among governance levels, placing subnational states in a situation of uncertainty that caused a fragmented crisis management, and therefore suboptimal policy learning processes. The study is based on the case of COVID‐19 governance in Switzerland, where, as in many other European countries, the management of the first pandemic wave was very centralized. However, the federal government avoided taking a strong lead during the subsequent waves. Consequently, pandemic management was marked by numerous fluctuations regarding who was in charge of the main COVID‐19 decisions between the federal and subnational governance levels. A media analysis (February 2020–March 2022) and an analysis of the gray literature show that crisis governance and policy learning processes were scattered across levels of governance, which impeded the accumulation of knowledge and know‐how. The article analyses how crises can give way to blame games between the levels of governance, thus hampering a coordinated crisis management and policy learning processes across the different stages of the pandemic.

Testing lockdown measures in epidemic outbreaks through mean-field models considering the social structure

Lately, concepts such as lockdown, quarantine, and social distancing have become very relevant since they have been associated with essential measures in the prevention and mitigation of COVID-19. While some conclusions about the effectiveness of these measures could be drawn from field observations, many mathematical models aimed to provide some clues. However, the reliability of these models is questioned, especially if the social structure is not included in them. In this work, we propose a mesoscopic model that allows the evaluation of the effect of measures such as social distancing and lockdown when the social topology is taken into account. The model is able to predict successive waves of infections without the need to account for reinfections, and it can qualitatively reproduce the wave patterns observed across many countries during the COVID-19 pandemic. Subsequent waves can have a higher peak of infections if the restrictiveness of the lockdown is above a certain threshold. The model is flexible and can implement various social distancing strategies by adjusting the restrictiveness and the duration of lockdown measures or specifying whether they occur once or repeatedly. It also includes the option to consider essential workers that do not isolate during a lockdown.

Waves of inequality: Income differences in intensive care due to Covid-19 in Sweden

Abstract Background Individuals in lower social strata were overall more likely to develop severe Covid-19 during the pandemic. However, specific conditions in terms of preparedness, knowledge and the properties of the virus itself changed during the course of the pandemic. Socioeconomic inequalities in Covid-19 may therefore shift over time. This study examines the relationship between income and intensive care (ICU) episodes due to Covid-19 in Sweden during three distinct waves. Methods This study uses Swedish register data on the total adult population and estimate the relative risk (RR) of ICU episodes due to Covid-19 by income quartile for each month between March 2020 and May 2022, and for each wave, using Poisson regression analyses. Results The first wave had modest income-related inequalities, while the second wave had a clear income gradient, with the lowest income quartile having an increased risk compared to the high-income group (RR: 1·55 [1·36 - 1·77]). In the third wave, the overall need for ICU decreased, but relative risks increased, particularly the top and bottom income quartiles (RR: 3·72 [3·50 - 3·96]). Inequalities in the third wave were partly explained by differential vaccination coverage by income quartile, although substantial inequalities remained after adjustment for vaccination status (RR: 2·39 [2·20 - 2·59]). Conclusions The study highlights the importance of considering the changing mechanisms that connect income and health during a novel pandemic. Health inequalities per income group increased for each subsequent wave. As the aetiology of Covid-19 became better understood those with more resources could better protect themselves from infection. Understanding the social dynamic of infectious diseases can help prepare for possible future pandemics. Key messages • Health inequalities in severe covid-19 infections increased as the pandemic progressed. • Understanding the social dynamic of infectious diseases can help prepare for possible future pandemics.

Characteristics and Presentations of Hospitalized Children Due to 3 Predominate COVID-19 Variants Within a Health Care Network.

Objective of this article is to describe differences in the demographic and clinical characteristics, severity of illness, and outcomes in pediatric patients with different SARS-CoV-2 variants. We conducted a retrospective study of pediatric patients admitted with COVID-19 during the 3 large waves of infection within a health network in New Jersey. We included demographic characteristics, clinical features, and outcomes and compared the data with respect to the different variants. Of 351 total patients included in this study, 74 were admitted during wave 1, 94 during wave 2, and 181 during wave 3. The median age of patients decreased from wave 1 (11.5 years) to wave 3 (3 years) (P = .0034). 87.7% of the patients were unvaccinated. The overall incidence of admissions due to pneumonia related to COVID-19 decreased in wave 3. COVID-19 bronchiolitis or croup admissions occurred mostly in wave 3. There was no significant difference in the number of patients requiring intensive care in any particular wave. Length of stay decreased across the waves (P < .0001). Treatments required did not vary between the waves except for a decrease in antibiotic use with each subsequent wave (P < .0001). The impact of COVID-19 on the pediatric population differs from the adult population, and the overall number of hospitalized children has mirrored the peak in cases observed during each infection wave. Our study illustrates the changes in clinical presentation and severity observed with the different coronavirus variants.

Why can’t smokers quit? Longitudinal study of smokers in the US using the Population Assessment of Tobacco and Health (PATH) waves 1 to 5

IntroductionMost adult cigarette smokers have tried unsuccessfully to quit. We followed participants in the Population Assessment of Tobacco and Health (PATH) study through five waves (2013–2019), comparing smoking, quit behaviors and other characteristics between persistent smokers and those who became and stayed former smokers. MethodsThe main analysis employed treatment effects to estimate mean differences in smoking and quitting behaviors among smoker groups. Logistic models were used to estimate predicted means based on continuing smokers’ demographic characteristics to ensure that any differences in outcomes did not come from differences in demographic characteristics. ResultsAmong smokers enrolled in PATH Wave 1, 68 % persisted in all subsequent waves. Compared with smokers who quit after Wave 1, persistent smokers had remarkably stable smoking behaviors, including significantly higher proportions of everyday smokers, consuming 10+ cigarettes per day, and smoking within 30 min of waking up. Persistent smokers were also less likely to try to quit completely, and experienced more negative symptoms from nicotine withdrawal. They also showed less interest in quitting and were less confident of being successful than smokers who quit by the next wave. Neither electronic nicotine delivery systems nor menthol played a role in continued smoking or quitting. ConclusionsThe characteristics and behaviors of persistent smokers in this study were stable over five waves of data collection during a six-year period, suggesting that these smokers need new cessation options.

Establishing a Panel Study of Refugees in Germany: First Wave Response and Panel Attrition from a Comparative Perspective

This article analyzes whether response patterns in surveys differ between the general population, regular immigrants, and recent refugees. Analyses show that the address quality of refugees contacted in the first wave of a panel study is worse than that of the general population, but of a similar quality to that of other recent immigrants. Once contacted, people in refugee households are more willing than others to participate in the first wave. In subsequent waves, this pattern changes. Address quality remains relatively low, and the motivation to participate deteriorates and is worse in comparison with other populations. However, Cox regression models of individual response behaviour reveal that this is mostly a composition effect. When socio-demographic and interviewer characteristics are taken into account, refugees have a lower risk of attrition than other immigrants, but they have a similar risk as the general population. This article provides important insights for the implementation of research about recent immigrants and refugees into ongoing panel studies.

Modeling the effect of non-pharmaceutical measures and vaccination on the spread of two variants of COVID-19 in India

An RNA virus, SARS-CoV-2 is capable of mutation, and vaccines developed to combat its earlier strains are comparatively less effective against its new emerging variants of concern. Therefore, it is proposed to formulate a two-strain COVID-19 deterministic model that incorporates non-pharmaceutical preventive strategies along with an imperfect and leaky vaccine. The control reproduction number (denoted by Rc) of the model is calculated using the next-generation matrix method. Rigorous model analysis elucidates that its disease-free equilibrium (DFE) is locally asymptotically stable when Rc<1. Using the central manifold theorem, the occurrence of subcritical bifurcation is proved when the relevant conditions required for its existence hold. However, the model exhibits transcritical bifurcation when the vaccinated population does not get infected. Additionally, the DFE point of this reduced case is globally asymptotically stable when Rc is sufficiently less than 1. Moreover, the model is analyzed to reveal the presence and global asymptotic stability (using the Lyapunov function approach) of endemic equilibrium points. The introduced model is calibrated and cross-validated with observed daily and cumulative data of Delta (1 April 2021 to 30 November 2021) and Omicron variant (1 December 2021 to 15 February 2022). Data fitting depicts that competitive exclusion exists among the variants as the Omicron variant tends to extinct other variants prevalent in that duration within a restricted timeframe. The model is examined, using the known and calibrated parameter values corresponding to the Omicron variant, to examine the impression of vaccination, quarantine, isolation, and lockdown on the prevalence of illness in India. The impact of fluctuations in vaccine and infection-induced immunities on daily and cumulative cases is studied. It is observed that vaccine-derived immunity exerts a greater influence on the current wave of the pandemic as compared to subsequent waves while natural infection immunity has a significant impact on future waves of the pandemic. Furthermore, there is a possibility of a future wave of the Omicron variant but with a relatively low peak. The minimum percentage of vaccinated people required to reach community-wide herd immunity has been estimated with respect to vaccine efficacy and various non-pharmaceutical control parameters.