This article contains:
The Oxford - AstraZeneca Vaccine
The Oxford - AstraZeneca Vaccine
Written By: Paphapin Pairojtanachai
A week ago, the University of Oxford and the biotech company AstraZeneca announced that, according to the Phase III trial data, their vaccine candidate ChAdOx1 nCoV-2019, also known as AZD1222, provides an effective protection against COVID-19.
The clinical trials of this vaccine consisted of two dosing regimens, one of which has an efficacy of 90%, and the other with 62% efficacy. When the data analysis from both regimens are combined, the average efficacy is 70.4%. Both dosing regimens involved two doses of the vaccine, administered to the volunteer one month apart. The difference between the two is that when a half dose rather than a full dose was given first, before being followed by another full dose, better results were yielded.
Over 11 thousand people were recruited to be a part of this trial, with roughly three-quarters of them receiving two full doses and the rest receiving a halved first dose and a standard second dose. Among the two regimens, only 131 of the volunteers acquired the SARS-CoV-2, and there were no hospitalized or serious COVID-19 cases in any of them. In addition, a reduction in asymptomatic infections indicates that the vaccine candidate is successful in preventing the transmission of the coronavirus. There are further trials going on in the US, Kenya, Japan, and India, and for a final analysis, over 24,000 participants from the United Kingdom, Brazil, and South Africa are being enlisted into the trial as well. Together, they will contribute to a large safety database for the vaccine candidate.
Compared to the vaccines designed by Pfizer and Moderna, the mechanism by which this Oxford vaccine works is entirely different. Whereas the Pfizer and Moderna vaccines inject a part of the coronavirus’ mRNA into the body, the ChAdOx1, which stands for Chimpanzee Adenovirus Oxford 1, utilizes a genetically modified common cold virus that once infected chimpanzees. The virus has been engineered in a way that allows it to “become the building block of a vaccine against almost anything”; this explains why it did not take long for the vaccine to be developed. The adjustments made stop the virus from infecting humans and also enable it to carry the “genetic blueprints” of the SARS-CoV-2, which are the spike proteins, in this case. Once the vaccine enters cells, the spike protein gets produced and the immune system is stimulated to destroy the infected cells. If the coronavirus is encountered for a second time, the antibodies and immune cells would be activated to fight the virus again.
Although some may view this Oxford vaccine as relatively disappointing in comparison to the 95% effective ones from Pfizer and Moderna, a 70% efficacy is still considered to be at a high level, considering the generally lower figures for traditional flu vaccines. Moreover, the Oxford vaccine has multiple advantages that could make its usage more practical than the others. Firstly, it can be stored and handled at normal refrigerated temperatures of 2 to 8 degrees Celsius for at least six months. This clearly implies that transporting the vaccine across the world would be much easier than those that require subzero temperatures for storage. Secondly, due to the greater advancements of Oxford University’s technology, the ChAdOx1 can be mass produced at a much lower cost — 3 to 5 times cheaper than those of Pfizer’s and Moderna’s.
Furthermore, in partnership with AstraZeneca, the vaccine producers have made a “no-profit pledge”, committing to the distribution of the vaccine to every corner of the world for the duration of the pandemic. Currently, up to 3 billion doses are being manufactured and will be ready for supply by 2021.
Further Readings:
For more information about Moderna’s vaccine, a related article can be accessed on the ICS Health Science Journal, titled “COVID-19 Update November 21, 2020”
For more information about Pfizer’s vaccine, a related article can be accessed on the ICS Health Science Journal, titled “COVID-19 Update November 16, 2020”
Comments