NOVEDADES DE LA VACUNA OXFORD-ZENECA PARA CO0MBATIR COVID2 19

AMIGOS; Buenas nuevas, La vacuna de la Universidad de Oxford, muestra grandes ventajas nol sólo para la prevención de la enfermedad, sino también para su tratamiento, Los estudios publicados en la revista "The Lancet", muestran mejoría de los síntomas desde las primeras semanas y protección inmunológica desde el inicio de la enfermedad. Además, en los 17,000 casos estudiados no hubo necesidad de hospitalización y sólo una fatalidad no relacionada al Covid 19. Aquí les presento el artículo original: FEBRERO 22, 2021 Study details single-dose administration and influence of prime-boost interval on efficacy of ChAdOx1 nCoV-19 The primary analysis of data from four blinded randomised controlled trials supports the findings reported in the interim analysis that the ChAdOx1 nCoV-19 vaccine, also known as AZD1222, is efficacious and safe against symptomatic coronavirus disease 2019 (COVID-19). Additionally, exploratory analyses show that higher vaccine efficacy is obtained with a longer prime-boost interval, and that a single dose of vaccine is efficacious in the first 90 days, providing further evidence for current policy. The findings are published in The Lancet. “The results of this primary analysis of two doses of ChAdOx1 nCoV-19 were consistent with those seen in the interim analysis of the trials and confirm that the vaccine is efficacious, with results varying by dose interval in exploratory analyses,” wrote Merryn Voysey, University of Oxford, Oxford, UK, and colleagues. “A 3-month dose interval might have advantages over a programme with a short dose interval for roll-out of a pandemic vaccine to protect the largest number of individuals in the population as early as possible when supplies are scarce, while also improving protection after receiving a second dose.” Between April 23 and December 6, 2020, a total of 24,422 participants were recruited and vaccinated across the four studies conducted in the UK, Brazil and South Africa. Participants were randomly assigned to receive two standard doses of ChAdOx1 nCoV-19 (5.0 × 1010 viral particles) or a control vaccine or saline placebo. In the UK trial, a subset of participants received a lower dose (2.2 × 1010 viral particles) of the ChAdOx1 nCoV-19 for the first dose. The primary outcome was virologically confirmed symptomatic COVID-19, defined as a nucleic acid amplification test (NAAT)-positive swab combined with at least one qualifying symptom more than 14 days after the second dose. In an analysis population of 17,178 study participants, there were 332 cases of primary symptomatic COVID-19 occurring more than 14 days after the second dose, of which 84 (1.0%) cases were reported among the 8,597 participants who received ChAdOx1 nCoV-19 and 248 (2.9%) in the 8,581 participants in the control group. Overall vaccine efficacy after the second dose was 66.7% (95% confidence interval [CI] 57.4–74.0). On the other hand, exploratory analyses showed that vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 after vaccination was 76.0% (95% CI 59.3–85.9). Further, modelling analysis indicated that protection did not wane during this initial 3-month period. Similarly, antibody levels were maintained during this period with minimal waning by day 90 (geometric mean ratio [GMR] 0.66, 95% CI 0.59–0.74). In addition, vaccine efficacy after two standard doses of vaccine was higher in those with a longer prime-boost interval (81.3% [95% CI 60.3–91.2] at ≥12 weeks) than in those with a short interval (55.1% [33.0–69.9] at <6 weeks). These observations, noted the authors, are supported by immunogenicity data that showed binding antibody responses were more than two-fold higher after an interval of 12 or more weeks compared with an interval of less than 6 weeks in those who were aged 18–55 years (GMR 2.32 [2.01–2.68]). Similarly, neutralising antibody titres measured by pseudovirus were higher after a longer interval before the second dose. There were no hospital admissions for COVID-19 in the ChAdOx1 nCoV-19 group after the initial 21-day exclusion period, while 15 admissions were reported in the control group. Meanwhile, 108 (0.9%) of 12,282 participants in the ChAdOx1 nCoV-19 group and 127 (1.1%) of 11,962 participants in the control group had serious adverse events. There were seven deaths considered unrelated to vaccination (two in the ChAdOx1 nCov-19 group and five in the control group), including one COVID-19-related death in one participant in the control group. “The analysis presented here provides strong evidence for the efficacy of two standard doses of the vaccine, which is the regimen approved by the Medicines and Healthcare products Regulatory Agency (MHRA) and other regulators,” the authors noted. “Exploratory analyses are presented in this report that show protection with dosing intervals from less than 6 weeks to 12 weeks or more and that a longer interval provides better protection after a booster dose without compromising protection in a 3-month period before the second dose is administered.” Nonetheless, the authors pointed out that “the studies were not designed to establish whether vaccine efficacy differed by dose interval and the presence of data of varying intervals arose because of the logistics of running large-scale clinical trials in a pandemic setting.” “These are therefore post-hoc exploratory analyses only with potential for multiple sources of bias, and were not prespecified. However, the analyses are presented here to provide a rigorous peer-reviewed interrogation of updated data that reflect the approach that is currently being used to underpin the deployment of ChAdOx1 nCoV-19 in the response to the pandemic,” the authors noted. Reference: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00432-3 SOURCE: The Lancet