لقاح جامعة أكسفورد/أسترازينيكا فعال بنسبة 90 في المائة
November 23, 2020 - The Oxford University and AstraZeneca Covid-19 vaccine can prevent up to 90% of people contracting coronavirus when it is administered as a half dose followed by a full dose at least one month apart.
The vaccine’s effectiveness depends on the dosing regimens -- it fell to just 62% when given as two full doses rather than a half-dose first. But scientists cautioned against seeing this as evidence that it would be less useful than rival vaccines from Pfizer/BioNTech and Moderna. These vaccines each prevented about 95% of cases according to interim data from their late-stage studies.
Oxford and AstraZeneca also said that there were no hospitalized or severe cases of the coronavirus in anyone who received the vaccine. They had also seen a reduction in asymptomatic infections, suggesting that the vaccine could reduce transmission.
The vaccine uses a chimpanzee adenovirus as a vector to carry the gene of the so-called surface spike protein. The coronavirus uses the spike protein to enter human cells to replicate.
After vaccination, the spike protein primes the immune system to attack the coronavirus if it later infects the body.