Lancet Oxford Vaccine Phase III Clinical: Prevention of Symptomatic COVID-19 Effectiveness 70%

This is the first complete Phase III trial results of oxford COVID-19 vaccine (AZD1222) for the Oxford vaccine.
First, the safety of the vaccine was acceptable, with only 3 out of 23,745 participants experiencing serious adverse events that could be related to the vaccine (one from the vaccine group, one from the control group, and one from the mask distribution group); The effectiveness was 62 per cent, while the effectiveness of the first half-dose and then the full dose was 90 per cent, with an average effectiveness of 70 per cent;
's COVID-19 vaccine uses a chimpanzee adenovirus vector that does not cause disease in humans and expresses the SARS-CoV-2 S protein.
this means that the vaccine passes the genetic code of the S protein to the cells of vaccinated people, who produce proteins and teach the immune system to recognize and attack viruses.
past trials have found that the vaccine induces antibody and T-cell immune responses and is safe for adults 18 years and older, including the elderly.
the new study, the authors analyzed data on 23,745 adults in the UK, Brazil and South Africa (11730, 10002 and 2013, respectively).
-term analysis, published on December 8th, compiled and analyzed the data, providing greater accuracy of efficacy and safety results than in individual trials, and providing a broader understanding of vaccine use in different populations.
in the trial, half of the subjects were vaccinated against COVID-19 and the other half were given control (meningococcal-binding vaccine or physiological saline).
The trial was originally designed to evaluate a single dose of the vaccine, but after reviewing the immunoreactive data from the Phase 1/2 study in the United Kingdom, which was found to enhance the immune response, another dose of the vaccine was added to the trial and, once approved, a second dose was given to the participants.
the COVID-19 vaccine group received two doses of the vaccine, each containing 5x1010 virus particles (standard dose).
, however, in the UK, some people (1,367 people) received half the first dose, followed by the second full dose.
this is because different batches of vaccines are quantified with different results.
low-dose/standard dose group does not include adults over 55 years of age, as low doses are given in the early stages of the trial prior to the recruitment of older persons.
authors used the number of cases of asymptomatic and asymptomatic infections to determine the effectiveness of the vaccine.
overall, the majority of participants were between the ages of 18 and 55 (82 per cent, 19588/23745) because people aged 56 and over were recruited later and would be studied in future trial analyses.
of the 11,636 people included in the vaccine effectiveness analysis for symptomatic diseases, 12 per cent (1418/11636) were elderly and the majority were white (83 per cent, 9625/11636).
of the 23,745 subjects, 168 experienced 175 serious adverse events during the trial, but 172 were not related to COVID-19 or the controlled vaccine.
1 case in the control group (hemolysmic anemia), 1 case in the COVID-19 vaccine group (transverse spinal corditis considered possible to be vaccine-related), and a case of severe fever (-gt;40 degrees C) was reported in South Africa to recover quickly without any other diagnosis and was not hospitalized.
all three participants have recovered or are recovering and will continue to participate in the trial.
131 cases of symptomatic COVID-19 disease among 11,636 British and Brazilian volunteers.
this included 30/5807 cases (0.5 per cent) in the vaccine group and 101/5829 (1.7 per cent) in the control group, equivalent to 70 per cent of the effectiveness of the vaccine.
when broken down by vaccine dose, the effectiveness of the vaccine was 62% for those who were vaccinated against the two standard doses, based on 27/4440 (0.6%) cases in the vaccine group and 71/4455 (1.6%) in the control group.
effective rate of vaccines in the low/standard dose group was 90%, based on 3/1367 (0.2%) cases in the vaccine group and 30/1374 cases (2.2%) in the control group.
five cases of symptomatic COVID-19 disease occurred in people over 55 years of age, but too few cases were available to assess the effectiveness of the vaccine in older people.
authors say the analysis will be completed in the future.
a total of 69 asymptomatic COVID-19 cases were found in the weekly COVID-19 test of 6,638 people in the UK.
this included 29/3288 cases (0.9%) in the vaccine group and 40/3350 (1.2%) cases in the control group, with a 27% effective rate of vaccine prevention of asymptomatic transmission.
subdivision group analysis, in the low/standard dose group, there were 7/1120 asymptomatic infections in the vaccine group and 17/1127 (1.5%) in the control group, so the effective rate of low/standard dose vaccines in preventing asymptomatic transmission was 59%.
Among those given two standard doses, there were 22/2168 (1%) cases in the vaccine group and 23/2223 cases (1%) in the control group, equivalent to 4% effectiveness of the vaccine in asymptomatic transmission.
monitored the serious illness and hospitalization of 23,745 subjects.
21 days after the first drug was given, 10 cases were admitted to hospital for COVID-19, all in the control group, of which 2 were severe and 1 died.
these are also secondary outcomes that need further confirmation.
authors note that they are not yet able to assess the duration of protection because the first trial began in April 2020 and all outbreaks of the disease accumulate within six months of the first dosing.
further evidence is needed to determine the duration of protection and whether an increase in the dose of the vaccine is required.
. Maria Deloria Knoll and Dr. Chizoba Wonodi of the Johns Hopkins University School of Public Health in the United States, who were not involved in the study, wrote in a related commentary: "Oxford-AstraZeneca and COVAX have reached an agreement of $2-3 per dose for low to middle income Fair use in the country offers good prospects, and it is important that the ChAdOx1 nCoV-19 vaccine can use conventional refrigeration chains compared to two high-cost mRNA vaccines, as ultra-low-temperature refrigerators needed to store mRNA vaccines may not be affordable and impractical in many countries and in environments such as nursing homes.
But if the two vaccines require different doses, this will increase the complexity of health workers who have little formal training but can reduce errors through innovative packaging and appropriate change management.
but it's hard not to be excited by these findings, with three safe and effective COVID-19 vaccines and 57 in clinical trials.
Because of the large number of manufacturers, the large global investment in production and the high level of cooperation in procurement and distribution, it is likely that 2021 will see different countries provide COVID-19 vaccines worldwide.
this time next year, we can personally celebrate the global control of SARS-CoV-2.
" References Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222 again) SARS-CoV-2: an interim analysis of four randomized controls in Brazil, South Africa, and the UK