ABSTRACT
New variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged, imposing the need for periodic booster doses. However, whether booster doses should be applied to the entire population or groups, and the booster doses interval, remains unclear. In this study, we evaluated humoral reactivity kinetics from before the first dose to 180 days after the third booster dose in different schedules in a well-controlled health worker cohort. Among the 2,506 employees, the first 500 vaccinated health workers were invited to participate. The third booster dose was administered 8 months after the first dose. Among the invited participants, 470 were included in the study; 258 received inactivated vaccine CoronaVac (VAC group) and 212 received viral vector vaccine ChAdOx1 (AZV group). The groups were homogeneous in terms of age and sex. 347 participants were followed up after the booster dose with AZV or BNT162b2 (Pfizer, BNT group): 63 with VAC/AZV, 117 with VAC/BNT, 72 with the AZV/AZV and 95 with AZV/BNT schedules. Blood samples were collected immediately before, 28 days after each dose and 180 days after the primary vaccination and booster dose. Anti-SARS-CoV-2 antibodies were measured by chemiluminescence and plaque reduction neutralization test (PRNT). Plasma immune mediators were quantified using a multiplex immunoassay. Geometric mean of antibodies increased 28 days after the second dose with 100 % seroconversion rate in both groups and decreased 180 days after the first dose. In the baseline-seropositive VAC group, the levels of plasma immune mediators increased after the second dose. Booster dose was applied at 4-6 months after the primary vaccination. Heterologous booster in VAC or AZV primary vaccinees were effective maintaining the titers of anti-SARS-CoV-2 antibodies even after 6 months of follow-up. The heterologous schedule induced higher and stable antibody reactivity, even after 180 days, protecting to ancestral (Wuhan), Delta, and Omicron variants.
ABSTRACT
ABSTRACT: Objective: The present study aims to dissect and identify the Barkow ligament (LB) in fetal specimens and describe its anatomical characteristics to contribute to its knowledge in the pediatric population and the clinical and surgical application of conditions associated with the Craniovertebral Junction (CVJ). ). Methods: This work evaluated 19 human fetuses aged 28-38 weeks. Of these, six specimens constituted the final sample and were studied through detailed dissections using coronal sections in an anterior approach up to the region described by the LB. Results: In all specimens, a thin fibrous band was found, horizontal and anterior to the axis tooth, with bilateral fixation on the occipital condyles, corroborating the results found for describing LB in adults. Conclusion: The LB is a congenital ligament that resists the extension of the atlantooccipital joint and may play a role in the stability of the CVJ. Level of Evidence III; Diagnostic Study.
RESUMO: Objetivo: O presente estudo tem como objetivo dissecar e identificar o ligamento de Barkow (LB) em espécimes fetais, e descrever suas caraterísticas anatômicas visando contribuir para o seu conhecimento em população pediátrica e na aplicação clínica e cirúrgica das condições associadas à Junção Craniovertebral (JCV). Métodos: Esse trabalho avaliou 19 fetos humanos de 28-38 semanas de vida. Destes, 6 espécimes constituíram a amostra final e foram estudados através de dissecções minuciosas utilizando secções coronais, em uma abordagem anterior, até a região de descrição do LB. Resultados: Em todos os espécimes foi encontrada uma delgada banda fibrosa, de disposição horizontal e anterior ao dente do áxis, com fixação bilateral nos côndilos occipitais, corroborando com os resultados encontrados para a descrição do LB em adultos. Conclusão: O LB é um ligamento congênito, que resiste a extensão da articulação atlantoccipital, e que pode ter papel na estabilidade da JCV. Nível de Evidência III; Estudo diagnóstico.
RESUMEN: Objetivo: El presente estudio tiene como objetivo diseccionar e identificar el ligamento de Barkow (LB) en especímenes fetales, y describir sus características anatómicas con el fin de contribuir a su conocimiento en la población pediátrica y en la aplicación clínica y quirúrgica de las condiciones asociadas a la unión craneovertebral. (UCV).). Métodos: Este trabajo evaluó 19 fetos humanos de entre 28 y 38 semanas. De estos, 6 ejemplares constituyeron la muestra final y fueron estudiados mediante disecciones detalladas mediante cortes coronales, en abordaje anterior, hasta la región descrita por el LB. Resultados: En todos los ejemplares se encontró una delgada banda fibrosa, horizontal y anterior al diente axis, con fijación bilateral en los cóndilos occipitales, corroborando los resultados encontrados para la descripción de LB en adultos. Conclusión: El LB es un ligamento congénito, que resiste la extensión de la articulación atlantooccipital, y que puede desempeñar un papel en la estabilidad de la UCV. Nivel de Evidencia III; Estudio Diagnóstico.
