The Oxford vaccine offers an average immunity of 70%
Efficacy increases to 90% if half a dose plus a whole dose is administered one month apart
LondonBetween 70% and 90% effective. This is what the preliminary analysis of the results of the third phase of the Oxford and AstraZeneca vaccine clinical trial, which the Anglo-Swedish company just made public on Monday, shows. The different degree of immunity is achieved depending on the number of doses. Last week, results from the second phase showed "strong" protection for the over-65 age group.
In relation to the Pfizer and Moderna vaccines, the results of the Oxford test could be a little disappointing, as both show an efficacy of 90% or more, according to data provided in the last two weeks. But one of the most relevant findings, and one that researchers are still analysing, is that when half a dose is given first and, a whole month later, a second full dose is administered, the vaccine protection is 90%.
As University of Leicester researcher Salvador Macip, from the department of cellular and molecular biology, assures the ARA, "immunity is not mathematical," so efficacy results may vary depending on the number of doses and the ratio. "Sometimes less gives more response. I don't think it's unreasonable," he concludes. In any case, protection above 70% is always a success, compared to that offered by some years of flu protection.
A perhaps the more interesting discovery is that volunteers who have received the vaccine in the sequence and amounts mentioned (1/2 + 1, one month apart) reduce asymptomatic infection much more. If further analysis confirms this, this would mean that the prototype developed by Dr Sarah Gilbert's team would manage to stop the spread of the infection and not only prevent the most serious symptoms.
The data made public this morning come from the clinical trial carried out in the UK and in Brazil on more than 20,000 people. What is surprising about the information provided by the pharmacist is that the administration of two full doses one month apart only achieves 62% effectiveness (70% on average when combined with data from volunteers who received one and a half doses). The study must "continue to accumulate more data and perform additional analysis to refine the efficacy reading and establish the duration of protection," says the pharmacist.
The technology used in the development of the Oxford vaccine is classic, and has been known and used for a long time. Basically, it involves the administration of a protein from the attenuated virus or parts of the virus, which directly stimulates the production of antibodies. In contrast, Moderna's and Pfizer's inject fragments of coronavirus genetic material (RNA) for the body's cells to use to make viral proteins that would cause the generation of antibodies
The great advantage of the Oxford vaccine over the other two is that it can be kept at the temperature of a conventional refrigerator (between 2 and 8 degrees Celsius). It is currently being manufactured in ten plants around the world.
Clinical trials are also underway in the United States, Japan, Russia, South Africa, Kenya and various Latin American countries. The company plans to enrol up to 60,000 participants worldwide.
