Articles: sars-cov-2.
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Knowledge about protection conferred by previous Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and/or vaccination against emerging viral variants allows clinicians, epidemiologists, and health authorities to predict and reduce the future Coronavirus Disease 2019 (COVID-19) burden. We investigated the risk and symptoms of SARS-CoV-2 (re)infection and vaccine breakthrough infection during the Delta and Omicron waves, depending on baseline immune status and subsequent vaccinations. ⋯ Our data suggest that hybrid immunity and booster vaccination are associated with a reduced risk and reduced symptom number of SARS-CoV-2 infection during Delta- and Omicron-dominant periods. For previously noninfected individuals, booster vaccination might reduce the risk of symptomatic Omicron infection, although this benefit seems to wane over time.
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Yonsei medical journal · Nov 2022
ReviewSARS-CoV-2 Omicron Variant of Concern: Everything You Wanted to Know about Omicron but Were Afraid to Ask.
As soon as the first case of the omicron variant of severe acute respiratory syndrome coronavirus 2 was reported in November 2021, it quickly spread worldwide with the emergence of several subvariants. Compared to previous variants, omicron was heavily mutated, especially for those in the Spike (S) protein and its receptor-binding domain. These mutations allowed the viruses to evade immune responses (i.e., previous infections and vaccine-elicited) and increase in transmissibility. ⋯ Interestingly, although omicron is highly infectious, it has less morbidity and mortality compared to previously identified variants, such as delta. Additionally, the mutations that allow the virus to evade immune responses also allow it to evade many of the monoclonal antibodies developed at the beginning of the pandemic for treatment. Here, we reviewed the omicron variant's epidemiology, genetics, transmissibility, disease severity, and responsiveness to vaccine and treatments.
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Development of optimal SARS-CoV-2 vaccines to induce potent, long-lasting immunity and provide cross-reactive protection against emerging variants remains a high priority. Here, we report that a modified porous silicon microparticle (mPSM) adjuvant to SARS-CoV-2 receptor-binding domain (RBD) vaccine activated dendritic cells and generated more potent and durable systemic humoral and type 1 helper T (Th) cell- mediated immune responses than alum-formulated RBD following parenteral vaccination, and protected mice from SARS-CoV-2 and Beta variant challenge. ⋯ Parenteral and intranasal prime and boost vaccinations with mPSM-RBD elicited stronger lung resident T and B cells and IgA responses compared to parenteral vaccination alone, which led to markedly diminished viral loads and inflammation in the lung following SARS-CoV-2 Delta variant challenge. Overall, our results suggest that mPSM is effective adjuvant for SARS-CoV-2 subunit vaccine in both systemic and mucosal vaccinations.
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Excessive inflammation is pathogenic in the pneumonitis associated with severe COVID-19. Neutrophils are among the most abundantly present leukocytes in the inflammatory infiltrates and may form neutrophil extracellular traps (NETs) under the local influence of cytokines. NETs constitute a defense mechanism against bacteria, but have also been shown to mediate tissue damage in a number of diseases. ⋯ Abundant neutrophils undergoing NETosis are found in the lungs of patients with fatal COVID-19, but no correlation was found with viral loads. The strong association between NETs and IL-8 points to this chemokine as a potentially causative factor. The function of cytotoxic T-lymphocytes in the immune responses against SARS-CoV-2 may be interfered with by the presence of NETs.
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The serial interval is a key epidemiological measure that quantifies the time between an infector's and an infectee's onset of symptoms. This measure helps investigate epidemiological links between cases, and is an important parameter in transmission models used to estimate transmissibility and inform control strategies. The emergence of multiple variants of concern (VOC) during the SARS-CoV-2 pandemic has led to uncertainties about potential changes in the serial interval of COVID-19. We estimated the household serial interval of multiple VOC using data collected by the Virus Watch study. This online, prospective, community cohort study followed-up entire households in England and Wales since mid-June 2020. ⋯ UK Medical Research Council and Wellcome Trust.