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PROBLEM: Despite being at increased risk for severe COVID-19, pregnant women were initially excluded from vaccine clinical trials, which limited data regarding vaccine effectiveness and protection in this group. Aiming to better understand the immune response to vaccination during pregnancy, we compared the kinetics and titers of neutralizing and IgG antibodies generated against SARS-CoV-2 during vaccination with BNT162b2 (Pfizer-BioNTech) or CoronaVac (Sinovac Biotech) in a cohort of pregnant women. METHODS OF STUDY: We evaluated participants before vaccination and 30 days after each vaccine dose, using a multiplex bead assay to measure IgG antibodies against SARS-CoV-2 antigens (total spike, spike-1, spike-2, receptor binding domain, and nucleocapsid) and a live virus fluorescence reduction neutralization assay (FRNA) to quantify neutralizing antibodies. RESULTS: Our data showed that vaccination resulted in a robust humoral response, with a considerable increase in the levels of IgG and neutralizing antibodies after the first vaccine dose and a sustained neutralizing response after the vaccine boost. In addition, antispike IgG assays presented a slight decrease after the second dose, while the neutralization rate remained stable. CONCLUSIONS: Immune response to the SARS-CoV-2 vaccine in pregnant women demonstrated an important increase in neutralizing antibodies.

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COVID-19 is caused by SARS-CoV-2, first identified in 2019. The Cuban vaccines, Abdala and Mambisa, have demonstrated efficacy in preventing SARS-CoV-2 infection. Immunoglobulin A (IgA) are the main line of defense against pathogens invading the respiratory or digestive tract and its presence in serum can be measured to assess vaccine efficacy. ELISAs are a valuable tool for assessing vaccine immunogenicity. These tests should be validated to ensure their reliability and suitability. The objective of this study was to validate a non-commercial ELISA for the quantification of total anti-RBD IgA in serum samples to support clinical studies. This assay demonstrated high clinical specificity (97.3 %). The accuracy and precision of the assay showed an overall error of less than 20 % at all levels in QCs. Re-evaluation of samples showed a mean difference of less than 30 % in 90.2 % of cases. Anti-RBD IgA titers correlated with viral neutralization titers and percentage inhibition of RBD-ACE2 binding. This assay was found to be highly accurate and reproducible for the quantification of anti-RBD IgA, met the most stringent acceptance criteria and is fit for purpose. It is currently being used to evaluate the immunogenicity of the Abdala and Mambisa vaccines.

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In this study, we examine the association between COVID-19 vaccination and antibody titer and whether this association varies by nutritional status and duration of school attendance using linear regression models applied to seven-year-old children from the 2015 Pelotas (Brazil) Birth Cohort (n = 2956). Antibody titers were 0.29 optical density (OD) titer units higher among vaccinated compared with unvaccinated children (95 % CI: 0.24, 0.34). Duration of school enrollment was associated with increased antibody titer, with each month being associated with a 0.15 unit increase in OD titer (95 % CI: 0.14, 0.16). Stunting was associated with lower COVID-19 titers among unvaccinated children (-0.10, 95 % CI: -0.21,0.004), but not among vaccinated children. Stunted children may have poorer immune responses to natural infection, but vaccination can overcome this deficit. Population-wide follow-up vaccination may be beneficial, particularly prior to school entry and for stunted children to reduce the risk of natural infection.

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BACKGROUND: The COVID-19 pandemic induced the rapid deployment of novel vaccines with pregnant persons identified as an at-risk population due to their increased risk of severe outcomes. Limited data on the immunogenicity of COVID-19 vaccines in pregnant persons were available at the time of implementation. To address this data gap, we developed a living systematic review summarizing emerging evidence on vaccine immunogenicity in pregnancy. METHODS: Following Cochrane, World Health Organization, and Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, we included studies on COVID-19 vaccines during pregnancy. We carried out comprehensive biweekly literature searches from March 2022 to October 2023, covering multiple databases. Study selection, data extraction and risk of bias assessment were conducted by pairs of authors independently. Immunogenicity outcomes, primarily post-vaccination neutralizing or binding antibody concentrations, were analyzed descriptively. Post-vaccination antibody ratios in pregnant versus nonpregnant individuals were calculated for the subset of studies that included nonpregnant comparators. RESULTS: By October 2023, our review encompassed 62 studies predominantly analyzing maternal sera (87%), with limited investigation regarding cord, neonatal and infant sera. Most studies investigated mRNA vaccines (97%) and focused on primary vaccination (82%), with some investigating booster doses (15%). Immunogenicity end points included spike-specific IgG (84%) and neutralizing antibodies (24%), with limited data on T-cell responses (3%). Antibodies were detectable after primary vaccination in most pregnant individuals, with similar or modestly attenuated concentrations compared to nonpregnant individuals (ratios > 0.7 for 5/6 estimates of spike-specific IgG), albeit with modest differences in antibody quality and kinetics. Long-term antibody-waning trajectories were similar between pregnant and nonpregnant individuals for up to 8 months after vaccination. CONCLUSIONS: mRNA COVID-19 vaccines induce a robust antibody response during pregnancy comparable (or modestly attenuated) relative to nonpregnant individuals. Immunogenicity data on non-mRNA vaccines are notably underrepresented in the existing literature.

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SARS-CoV-2 emerged rapidly as a pandemic, leading to the urgent development and authorization for the use of several vaccines, with questions relating to immunogenicity in previously infected people or to virus variants. As such, we sought to determine the humoral and cellular immune response of healthy adults to distinct SARS-CoV-2 variants upon AZD1222/COVISHIELD vaccination, using chemiluminescence (CMIA), neutralizing antibody (PRNT) and analysis of activation-induced marker (AIM) by flow cytometry, respectively. We enrolled 75 volunteers, including 26 individuals previously infected with SARS-CoV-2. Our findings demonstrated that AZD1222 vaccine induced increased levels of SARS-CoV-2-specific antibodies after two-dose vaccination scheme, as detected by CMIA (mean = 49 BAU/mL to 743 BAU/mL) and PRNT (GMT = 3, 95 % CI 2-4, to 19, 11-34). After vaccination, all volunteers presented detectable antibodies by CMIA while only 64 % presented positive PRNT. Seroconversion rates were 91 % and 48 % by CMIA and 59 % by PRNT after the first and second dose, respectively. The PRNT to Delta variant demonstrated lower titers as compared to Wuhan-like and a seroconversion of 57 %. Although by CMIA all volunteers were classified as high responders, some volunteers showed no response by PRNT and AIM. In general, previously infected volunteers had higher post-vaccination antibody titers after each dose. CD4+ T cell response was generally higher than CD8+ T cells for all variants. Overall, we observed that AZD1222 vaccination induced cross-reactivity to SARS-CoV-2 variants, in both cellular and humoral responses. During volunteer follow-up, we observed that the elevated antibody titers are lasting and were incremented by the first booster. In conclusion, our findings showed that AZD1222 vaccine was able to induce a robust immune response upon primary immunization, with cross-reactivity for the Delta VOC.

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A total of 5011 adult volunteers attending vaccination centers in different regions of Colombia were enrolled in a 1-year prospective observational cohort study to evaluate the immunogenicity and effectiveness of SARS-CoV-2-based vaccines as part of a National Vaccine Program established to contain the COVID-19 pandemic. Following informed consent, 5,011 participants underwent a sociodemographic survey and PCR testing to assess SARS-CoV-2 infection. Blood samples were collected, and serum fractions were obtained from a participant subsample (n = 3441) at six-time points to assess virus-specific IgG responses to the Spike protein, its Receptor Binding Domain, and the Nucleoprotein by ELISA. Additionally, antibody-neutralizing activity was evaluated using a cPass SARS-CoV-2 neutralization kit. Most participants (95.8%; n = 4802) received between one Ad26. COV2.S (Janssen vaccine) and four vaccine doses of BNT162b2 (Pfizer/BioNTech), AZD1222 (AstraZeneca), mRNA-1273 (Moderna), CoronaVac (Sinovac), with some receiving vaccine combinations; a small group, 4.2% (n = 209), remained unvaccinated. Throughout the study, only 8.76% (n = 439) of the participants tested positive for SARS-CoV-2 by PCR. Notably, all participants seroconverted for IgG antibodies, with high seropositivity rates for S (99.8%; n = 4795), RBD (99.7%; n = 1691), and N (92.7%; n = 3072) proteins. Moreover, significant (92%-97%) neutralizing activity was observed for all four SARS-CoV-2 circulating variants. This study highlights the importance of assessing the duration of the IgG response to SARS-CoV-2 elicited by vaccination and infection, and the antibody neutralizing activity as a potential surrogate marker of protection. These findings provide important insight for further strengthening the vaccination strategies to control COVID-19.

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The COVID-19 pandemic has posed a significant threat to global health systems, with extensive impacts across many sectors of society. The pandemic has been responsible for millions of deaths worldwide since its first identification in late 2019. Several actions have been taken to prevent the disease, including the unprecedented fast development and global vaccination campaigns, which were pivotal in reducing symptoms and deaths. Given the impact of the pandemic, the continuous changes of the virus, and present vaccine technologies, this review analyzes how, so far, we have met the challenge posed by the emergence of new variants and discusses how next-generation pan-coronavirus vaccines, with enhanced longevity and breadth of immune responses, may be tackled with alternative administration routes and antigen delivery platforms. By addressing these critical aspects, this review aims to contribute to the ongoing efforts to achieve long-term control of COVID-19, stimulating the discussion and work on next-generation vaccines capable of facing future waves of infection.

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Immunocompromised individuals were considered high-risk for severe disease due to SARS COV-2 infection. This study aimed to describe the safety of two doses of COVID-19 adsorbed inactivated vaccine (CoronaVac; Sinovac/Butantan), followed by additional doses of mRNA BNT162b2 (Pfizer/BioNTech) in immunocompromised (IC) adults, compared to immunocompetent/healthy (H) individuals. This phase 4, multicenter, open label study included solid organ transplant and hematopoietic stem cell transplant recipients, cancer patients and people with inborn errors of immunity with defects in antibody production, rheumatic, end-stage chronic kidney or liver disease, who were enrolled in the IC group. Participants received two doses of CoronaVac and additional doses of mRNA BNT162b2. Adverse reactions (AR) data were collected within seven days after each vaccination. Serious adverse events and of special interest (AESI) were monitored throughout the study. We included 241 immunocompromised and 100 immunocompetent subjects. Arthralgia, fatigue, myalgia, and nausea were more frequent in the IC group after CoronaVac. Following the first additional dose of mRNA BNT162, pain, induration, and tenderness at injection site, fatigue and myalgia were more frequent in the H group. A heart transplant recipient had a graft rejection temporally associated with the second CoronaVac dose, but there was no literature evidence of causal association. Four cases of AESI were considered related to the vaccine: three erythema multiforme after CoronaVac, all in IC participants, and one paresthesia after mRNA, in a H participant. Our findings were comparable to other studies that evaluated the safety of COVID-19 vaccines in different immunocompromised populations. Both vaccines were safe for immunocompromised participants.

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COVID-19 caused a public health emergency, which instituted a global effort to develop vaccines using different platforms, such as basic types and new-generation vaccines. Considering the importance of vaccination in preventing the severity of infectious diseases and the success in developing and approving vaccines against COVID-19 in record time, it is essential to learn about the characteristics of these vaccines. This study aimed to conduct a structured, systematic review following the PRISMA guideline, to analyze the general characteristics of vaccines approved globally for use against COVID-19. We used the list of approved vaccines available by the WHO as guidance to search for studies in the literature. We searched the terms "SARS-CoV-2 and vaccine and safety and efficacy" in the MEDLINE via PUBMED and Web of Science databases. We conducted the research on both bases, including complete articles published from January 2020 to June 2023. The selection of files occurred between May/2021 and June/2023. Therefore, the paper did not consider articles published after this period or vaccines approved after this moment. This study only included approved vaccines; phase three studies published in English. We found 11 published articles from phase three that met the established criteria. The vaccines included in this study were: Cominarty, mRNA-1273 or Spikevax, Vaxzevria or AZD1222 or Covishield, CoronaVac or PicoVacc, and Ad26.COV2.S, SputnikV or Gam-Covid-Vac, Covaxin, NVX-CoV2373 or Covovax or Nuvaxovid, WIV04 and HB02, CoVLP or Covifenz and Convidecia or Ad5-nCoV. We summarized the main findings of each vaccine, considering the vaccine composition, number of doses, efficacy analyses, and main adverse effects. In general, the vaccines had high efficacy rates and few adverse effects. Efficacy values are important for vaccine approval, but they will not necessarily reflect the real-world impact of vaccination. It was seen that the effectiveness of COV2.S, CoronaVac/PicoVacc, Cominarty, and Covaxin vaccines was lower than the efficacy, whereas, for AZD1222/Vaxzevria/Covishield, the two parameters remained at similar rates. All vaccines evaluated have different compositions, dosages, populations, and study designs. All are effective in at least preventing symptomatic COVID-19, causing mild or moderate adverse effects when present.

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Understanding the dynamics of antibody responses following vaccination and SARS-CoV-2 infection is important for informing effective vaccination strategies and other public health interventions. This study investigates SARS-CoV-2 antibody dynamics in a Puerto Rican cohort, analyzing how IgG levels vary by vaccination status and previous infection. We assess waning immunity and the distribution of hybrid immunity with the aim to inform public health strategies and vaccination programs in Puerto Rico and similar settings. We conducted a prospective, longitudinal cohort study to identify SARS-CoV-2 infections and related outcomes in Ponce, Puerto Rico, from June 2020-August 2022. Participants provided self-collected nasal swabs every week and serum every six months for RT-PCR and IgG testing, respectively. IgG reactivity against nucleocapsid (N) antigens, which generally indicate previous infection, and spike (S1) and receptor-binding domain (RBD) antigens, which indicate history of either infection or vaccination, was assessed using the Luminex Corporation xMAP® SARS-CoV-2 Multi-Antigen IgG Assay. Prior infection was defined by positive RT-PCRs, categorized by the predominant circulating SARS-CoV-2 variant at the event time. Demographic information, medical history, and COVID-19 vaccination history were collected through standardized questionnaires. Of 882 participants included in our analysis, 34.0% experienced at least one SARS-CoV-2 infection, with most (78.7%) occurring during the Omicron wave (December 2021 onwards). SARS-CoV-2 antibody prevalence increased over time, reaching 98.4% by the final serum collection, 67.0% attributable to vaccination alone, 1.6% from infection alone, and 31.4% from both. Regardless of prior infection status, RBD and S1 IgG levels gradually declined following two vaccine doses. A third dose boosted these antibody levels and showed a slower decline over time. N-antibody levels peaked during the Omicron surge and waned over time. Vaccination in individuals with prior SARS-CoV-2 infection elicited the highest and most durable antibody responses. N or S1 seropositivity was associated with lower odds of a subsequent positive PCR test during the Omicron period, with N antibodies showing a stronger association. By elucidating the differential decay of RBD and S1 antibodies following vaccination and the complexities of N-antibody response following infection, this study in a Puerto Rican cohort strengthens the foundation for developing targeted interventions and public health strategies.

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During COVID-19 pandemic, international pharmaceutical companies put effort to build global manufacturing networks for vaccines. Soberana Plus vaccine, a recombinant protein based vaccine (RBD dimer), with the trade name of PastoCovac Plus in Iran, is based on a protein subunit platform in Cuba and completed preclinical and toxicological assessments. This study aimed at presenting the steps of vaccine technology transfer from Cuba to Iran. This study provides the first practical comparability results in Iran to ensure the quality, safety and efficacy of a protein subunit vaccine against COVID-19 after a successful technology transfer from Cuba. PastoCovac Plus was transferred to Iran at the formulation stage. The assessment of the active ingredient pharmaceutical (API) was achieved through physicochemical and clinical data collection and tests to assure if there was any adverse impact on the vaccination results. In order to assess the quality of the vaccine product after technology transfer, we sought different properties including regulatory features, physicochemical quality, vaccine potency and stability as well as its immunogenicity and safety. Following the evaluation of the clinical quality attributes (CQAs) based on the standard protocols, the results showed that the two vaccines are highly similar and comparable, with no considerable effect on safety or efficacy profiles. The CQAs were all in the acceptance limits in terms of safety and efficacy as well as clinical evaluation results. The immunogenicity evaluation also confirmed no significant differences between the vaccines regarding reinfection (P = 0.199) or vaccine breakthrough (P = 0.176). Furthermore, the level of anti-spike and neutralizing antibodies in the both vaccine groups was not significantly different indicating the equality of performance between the two vaccines. According to the results of the quality and clinical assessment of this study, we achieved an acceptable quality attributes and acceptant limits in terms of safety and efficacy of the vaccines pre and post technology transfer.

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INTRODUCTION: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has spread worldwide since 2019. Survey of the antibodies against SARS-CoV-2 is one of the most important measures of immunity since it can give an idea on the effectiveness of administered vaccines and the serologic status of individuals. We determined the concentrations of blood IgM and IgG against three SARS-CoV-2 proteins in vaccinated teachers and students among a university population from Chihuahua, Mexico. METHODOLOGY: Humoral response surveillance against the 3C-like proteinase (3CLpro), nuclear protein (NP), and receptor binding domain (RBD) of SARS-CoV-2 was carried out. A total of 239 samples were analyzed: 67 from teachers who were vaccinated with CanSino and 172 from students (27.9% were vaccinated with AstraZeneca, 32.6% with Sinovac, 24.4% with Pfizer-BioNTech, 15.1% with other vaccines). RESULTS: Significant differences in the levels of IgG were observed between serum from individuals prior to vaccination (preimmunization serum) and from those that were vaccinated with CanSino. However, samples from asymptomatic individuals did not show differences between the preimmunization and post-immunization serum. The three vaccinated groups (AstraZeneca, Pfizer and Sinovac) did not show significant differences in anti-RBD IgG antibody titers compared to the positive control group, except for a Pfizer non-COVID-19 subgroup where the level of antibodies in the Pfizer group was 1.7 times higher. Neither vaccine group showed significant differences between those individuals who previously had COVID-19 and uninfected individuals. CONCLUSIONS: These results provide a picture of the situation at the time when in-person classes resumed.

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The global impact of the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic in 2019-2020 has led to significant changes in worldwide vaccination and immune prophylactic approaches. In this study, our research delves into a new immunization strategy that does not involve the use of additional adjuvants or preservatives, focusing on the effects of virus fusion with a bacterial nanostructure. The experimental procedures outlined in this paper involved the cultivation of SARS-CoV-2, the production, extraction, and nanocharacterization of outer membrane vesicles (OMV) from Neisseria meningitidis, immunization of mice with two doses of OMV combined with SARS-CoV-2, and the use of mesoporous silica SBa15 and SBa16 adsorbed to the same virus. The immune response was assessed through an indirect elisa method, analysis of cytokine expression profiles, and seroneutralization of the SARS-CoV-2 strain. The characterizations of associated OMV - SARS-CoV-2 and adsorption SBa15 and SBa16 were performed using Nanosight Tracking Analysis (NTA), which showed a high density of particles in the formulation. mice were then immunized, resulting in an immune response that produced high levels of neutralizing antibodies in IgG and IgG1 mouse immunoglobulins. In addition, expressions of IL-2, IL-4, and IL-23 in spleen cells were reinforced after the vaccination process. The comparative study of these three vaccine formulations has shown that the development of new vaccines for SARS-CoV-2 should take into consideration the production of neutralizing antibodies and the maintenance of immunological memory.

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The high transmissibility, rapid evolution, and immune escape of SARS-CoV-2 variants can influence the course of infection and, in turn, morbidity and mortality in COVID-19, posing a challenge in controlling transmission rates and contributing to the emergence and spread of new variants. Understanding the factors that shape viral genetic variation is essential for comprehending the evolution and transmission of SARS-CoV-2, especially in vaccinated individuals where immune response plays a role in the progression and spread of this disease. In this context, we evaluated the impact of immunity induced by the CoronaVac vaccine (Butantan/Sinovac) on intra-host genetic diversity, analyzing 118 whole-genome sequences of SARS-CoV-2 from unvaccinated and vaccinated patients infected with the Gamma variant. Vaccination with CoronaVac favors negative selection at the intra-host level in different genomic regions. It prevents greater genetic diversity of SARS-CoV-2, reinforcing the importance of vaccination in reducing the emergence of new mutations and virus transmission.

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COVID-19 vaccine evaluations are mainly focused on antibody analyses, but there is growing interest in measuring the cellular immune responses from the researchers evaluating these vaccines. The cellular responses to several COVID-19 vaccines have been studied using the enzyme-linked immunospot (ELISPOT) assay for IFN-γ. However, the ELISPOT assay is no longer used only for research purpose and so the performance of this assay must be validated. Since the bioanalytical validation of ELISPOT-IFN-γ is essential for evaluating the method's effectiveness and establishing confidence in a vaccine's immunogenicity, the present work validates the ELISPOT-IFN-γ assay's performance in determining the frequency of IFN-γ-producing cells after stimulation with the SARS-CoV-2 spike protein. The validation was performed in peripheral blood mononuclear cells from volunteers immunized with anti-COVID-19 vaccines. According to the findings, the LOD was 17 SFU and the LLOQ was 22 SFU, which makes the method highly sensitive and suitable for evaluating low levels of cellular responses. The procedure's accuracy is confirmed by the correlation coefficients for the spike protein and anti-CD3+, being 0.98 and 0.95, respectively. The repeatability and intermediate precision tests were confirmed to be reliable by obtaining a coefficient of variation of ≤25%. The results obtained in this validation enable the assay to be employed for studying antigen-specific cells and evaluating cellular responses to vaccines.

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BACKGROUND: Although important information concerning COVID-19 vaccination is available, the effects of the CoronaVac and ChadOx-1 vaccines on immunity and the redox balance in the upper airway mucosa of the aged population are not fully understood. Therefore, the aim of this study was to investigate the impacts of two doses of the CoronaVac or ChadOx-1 vaccine on immune/inflammatory responses and oxidative stress in the airway mucosa of older adults. METHODS: Seventy-six older adults of both sexes, with a mean age of 75.1 ± 6.4 years, were separated according to vaccination status into the CoronaVac (n = 52) and ChadOx-1 (n = 24) groups. Saliva samples were collected before (pre) and 30 days after (post) the administration of the second dose of the CoronaVac or ChadOx-1 vaccine to assess the levels of antibodies (sIgA and IgG), antimicrobial peptides, cytokines, and oxidant/antioxidant agents. RESULTS: The immunogenicity in the ChadOx-1 group was 37.5% for sIgA and 25% for IgG, while that in the CoronaVac group was 18.9% for sIgA and 13.2% for IgG. Intergroup analysis revealed that (1) lower levels of IFN-α, IFN-γ, and IL-10 and a greater IFN-γ/IL-10 ratio, in addition to a greater IL-6/IL-10 ratio, were found in both the pre- and postvaccination periods, and (2) lower levels of total sIgA, IL-12p70, IL-17A, TNF-α, and the IL-12p70/IL-10 ratio, in addition to higher levels of specific sIgA for SARS-CoV-2 antigens and lysozyme, were observed only in the postvaccination period in the ChadOx-1 group than in the CoronaVac group. Intragroup analysis revealed (1) a significant increase in the salivary levels of total peroxides in the postvaccination period compared to those in the prevaccination period in both volunteer groups; (2) a decrease in the levels of lysozyme and the ratio between total antioxidant capacity (TAC) and total peroxides in the postvaccination period in the CoronaVac group compared with those in the prevaccination period; and (3) decreases in the TNF-α, IL-6, and IL-12p70 levels, and the IL-12p70/IL-10 ratio in the ChadoX-1 group, as well as a higher lactoferrin concentration in the postvaccination period than in the prevaccination period. Several positive and negative correlations between the parameters assessed here were found. CONCLUSIONS: In general, the ChadOx-1 group exhibited improvements in both immune/inflammatory responses and redox balance and greater immunogenicity than did the CoronaVac group.

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This study evaluated the explanatory factors of humoral immune response in older adults admitted to long-term care institutions in Buenos Aires, Argentina, up to 180 days after vaccination. An open-label, prospective, multicenter cohort study was conducted with volunteers who received two doses of the Sputnik V, Sinopharm, or AZD1222 vaccines. Plasma samples were analyzed at 0 and 21 days after the first dose, 21 days after the second dose, and 120 and 180 days after the first dose. Marginal linear models and generalized additives mixed models were adjusted to determine the behavior of anti-spike IgG antibody concentration over time according to exposure group (naïve/no-naïve) and vaccine. Occurrence of an outbreak of COVID-19 in long-term care institutions and comorbidities were the covariates analyzed. A total of 773 participants were included, with a mean age of 83 years (IQR: 76-89). Results showed that antibody levels in the naïve: Sinopharm group were significantly lower to the other groups (p < 0.05). Antibody levels in the no-naïve: Sinopharm group were similar to those in the naïve group who received AZD1222 (p = 0.945) or Sputnik V (p = 1). Participants exposed to outbreaks in long-term care institutions had significantly higher antibody levels, regardless of exposure group and vaccine (p < 0.001). In conclusion, previous exposure to COVID-19, type of vaccine, and admittance into a long-term care institution with a history of outbreaks are factors to be considered in future epidemic events with transmission dynamics and immunological mechanisms similar to COVID-19, in populations similar to the one analyzed.

El objetivo de este trabajo fue evaluar los factores explicativos de la respuesta inmune humoral en adultos mayores de establecimientos de estancia prolongada de Buenos Aires, Argentina, hasta 180 días post vacunación. Se utilizó un diseño de cohorte abierta, prospectiva, multicéntrica, con voluntarios que recibieron dos dosis de vacunas Sputnik V, Sinopharm o AZD1222. Se analizaron muestras de plasma en los tiempos 0, 21 días post primera dosis, 21 días post segunda dosis, 120 y 180 días post primera dosis. Se ajustaron modelos lineales marginales y aditivos generalizados mixtos para evaluar el comportamiento de la concentración de anticuerpos IgG anti-Spike en el tiempo según grupo de exposición (naïve/no-naïve) y vacuna. Las covariables analizadas fueron: ocurrencia de brote de COVID-19 en establecimientos de estancia prolongada y comorbilidades. Se incluyeron en el análisis 773 participantes con una mediana de edad de 83 años (RIQ: 76-89). Al final del estudio, los niveles de anticuerpos del grupo naïve: Sinopharm fueron significativamente menores que el resto de los grupos (p < 0,05); los del no-naïve: Sinopharm resultaron similares a los naïve que recibieron AZD1222 (p = 0,945) o Sputnik V (p = 1). Los participantes expuestos a brotes en establecimientos de estancia prolongada presentaron niveles de anticuerpos significativamente mayores, independientemente del grupo de exposición y la vacuna (p < 0,001). Concluimos que la exposición previa a COVID-19, el tipo de vacuna y la pertenencia a un establecimiento de estancia prolongada con antecedente de brote son factores a considerar frente a futuros eventos epidémicos con dinámicas de transmisión y mecanismos inmunológicos similares al COVID-19, en poblaciones similares a la analizada en este trabajo.

Este estudo teve como objetivo avaliar os fatores explicativos da resposta imune humoral em idosos em instituições de longa permanência em Buenos Aires, Argentina, até 180 dias após a vacinação. Foi realizado um estudo de coorte aberto, prospectivo e multicêntrico, com voluntários que receberam duas doses das vacinas Sputnik V, Sinopharm ou AZD1222. As amostras de plasma foram analisadas nos tempos 0, 21 dias após a primeira dose, 21 dias após a segunda dose, 120 e 180 dias após a primeira dose. Os modelos lineares marginais e os aditivos generalizados mistos foram ajustados para determinar o comportamento da concentração de anticorpos IgG anti-Spike ao longo do tempo de acordo com o grupo de exposição (naïve/no-naïve) e vacina. As covariáveis analisadas foram ocorrência de pico de COVID-19 nas instituições de longa permanência e comorbidades. Foram incluídos 773 participantes, com média de idade de 83 anos (IIQ: 76-89). Os resultados apontaram níveis de anticorpos do grupo naïve: Sinopharm significativamente mais baixos do que os outros grupos (p < 0,05); e as variáveis do grupo no-naïve: Sinopharm foram semelhantes à do grupo naïve que recebeu AZD1222 (p = 0,945) ou Sputnik V (p = 1). Os participantes expostos a picos nas instituições de longa permanência apresentaram níveis de anticorpos significativamente maiores, independentemente do grupo de exposição e da vacina (p < 0,001). Conclui-se que a exposição prévia à COVID-19, tipo de vacina e adesão a uma instituição de longa permanência com histórico de pico são fatores a serem considerados em futuros eventos epidêmicos com dinâmica de transmissão e mecanismos imunológicos semelhantes à COVID-19, em populações semelhantes à analisada neste trabalho.

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Vaccination has played a critical role in mitigating COVID-19. Despite the availability of licensed vaccines, there remains a pressing need for improved vaccine platforms that provide high protection, safety, and versatility, while also reducing vaccine costs. In response to these challenges, our aim is to create a self-adjuvanted vaccine against SARS-CoV-2, utilizing Virus-Like Particles (VLPs) as the foundation. To achieve this, we produced bacteriophage (Qß) VLPs in a prokaryotic system and purified them using a rapid and cost-effective strategy involving organic solvents. This method aims to solubilize lipids and components of the cell membrane to eliminate endotoxins present in bacterial samples. For vaccine formulation, Receptor Binding Domain (RBD) antigens were conjugated using chemical crosslinkers, a process compatible with Good Manufacturing Practice (GMP) standards. Transmission Electron Microscopy (TEM) confirmed the expected folding and spatial configuration of the QßVLPs vaccine. Additionally, vaccine formulation assessment involved SDS-PAGE stained with Coomassie Brilliant Blue, Western blotting, and stereomicroscopic experiments. In vitro and in vivo evaluations of the vaccine formulation were conducted to assess its capacity to induce a protective immune response without causing side effects. Vaccine doses of 20 µg and 50 µg stimulated the production of neutralizing antibodies. In in vivo testing, the group of animals vaccinated with 50 µg of vaccine formulation provided complete protection against virus infection, maintaining stable body weight without showing signs of disease. In conclusion, the QßVLPs-RBD vaccine has proven to be effective and safe, eliminating the necessity for supplementary adjuvants and offering a financially feasible approach. Moreover, this vaccine platform demonstrates flexibility in targeting Variants of Concern (VOCs) via established conjugation protocols with VLPs.

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The emergence of new SARS-CoV-2 variants of concern associated with waning immunity induced by natural infection or vaccines currently in use suggests that the COVID-19 pandemic will become endemic. Investing in new booster vaccines using different platforms is a promising way to enhance protection and keep the disease under control. Here, we evaluated the immunogenicity, efficacy, and safety of the SpiN-Tec vaccine, based on a chimeric recombinant protein (SpiN) adjuvanted with CTVad1 (MF59-based adjuvant), aiming at boosting immunity against variants of concern of SARS-CoV-2. Immunization of K18-hACE-2 transgenic mice and hamsters induced high antibody titers and cellular immune response to the SpiN protein as well as to its components, RBD and N proteins. Importantly in a heterologous prime/boost protocol with a COVID-19 vaccine approved for emergency use (ChAdOx1), SpiN-Tec enhanced the level of circulation neutralizing antibodies (nAb). In addition to protection against the Wuhan isolate, protection against the Delta and Omicron variants was also observed as shown by reduced viral load and lung pathology. Toxicity and safety tests performed in rats demonstrated that the SpiN-Tec vaccine was safe and, based on these results, the SpiN-Tec phase I/II clinical trial was approved.

RESUMO

En el contexto de la pandemia por la enfermedad por coronavirus de 2019 (COVID-19) y del plan nacional de vacunación en respuesta a la misma, en el documento normativo de "Lineamientos técnicos y operativos para la introducción de la vacuna contra la COVID-19" (páginas 12 y 36), se estableció que se emitirán y actualizarán lineamientos técnicos de aplicación específicos para cada vacuna que no esté incluida en los lineamientos, y que se formularan lineamientos operativos de programación para todas la/s vacuna/s que el país adquiera. Desde marzo del 2020, se han notificado 193 millones de casos confirmados de COVID-19 y 2,97 millones de muertes en la Región de las Américas, lo que la convierte en la región con la tasa de letalidad más alta del mundo. En mayo del 2023, la prevalencia mundial estaba dominada por las subvariantes de ómicron, incluidas las subvariantes XBB.1.5, XBB.1.16 y XBB.1.9. Más recientemente, han surgido otras subvariantes adicionales de ómicron, como la EG.5 y la BA.2.86. Hasta ahora, los países y territorios de la Región de las Américas han administrado más de 2100 millones de dosis de vacunas contra la COVID-19. A pesar de este esfuerzo, solo el 71,3% de la población de América Latina y el Caribe ha recibido el esquema completo de vacunación contra esta enfermedad, con diferencias de cobertura entre los distintos países y grupos de riesgo. En noviembre del 2023, el número de casos está aumentando nuevamente en todas las subregiones de la Región de las Américas, excepto en el Caribe, aunque a un ritmo mucho más lento que en el mismo período del 2020 o del 2021. Después de cuatro años de pandemia, la mayor parte de las personas del mundo tienen cierta inmunidad frente al SARS-CoV-2 como consecuencia de la infección, la vacunación o ambas cosas. A la vez, se han observado reducciones significativas en la enfermedad grave y la muerte relacionada con el SARS-CoV-2 en todos los grupos etarios. En esta etapa de la pandemia, los beneficios de recibir el esquema primario completo de dos dosis sucesivas han pasado a ser limitados. El GTA apoya firmemente la recomendación del SAGE de que los países continúen centrándose en lograr una cobertura alta de vacunación en los grupos de riesgo prioritarios. Entre ellos se encuentran las personas mayores, las embarazadas, las personas con comorbilidades, las personas inmunodeprimidas y los trabajadores de salud. El aumento de la tasa de cobertura con el esquema primario tiene un impacto superior en la reducción de las hospitalizaciones y las muertes al que tiene el uso de un suministro equivalente de vacunas para aumentar la tasa de cobertura con las dosis de refuerzo. Concretamente: o Los países pueden reducir sus tasas de morbilidad y mortalidad si se aseguran de que todas las personas reciban al menos una dosis de una vacuna contra la COVID19. o En el caso de las vacunas contra la COVID-19 de virus inactivados (es decir, las vacunas producidas por Bharat, Sinovac, Sinopharm y Valneva), se requieren dos dosis como parte de este esquema inicial. Las personas de los grupos prioritarios son las tienen una mayor probabilidad de enfermar de gravedad omorir. Cualquier disminución de la efectividad de la vacuna, por pequeña que sea, aumenta el número de personas que presentan un cuadro grave o mueren. Por lo tanto, se recomienda la administración de dosis de refuerzo solamente para las personas que forman parte de grupos 2 prioritarios...(AU)