A year of trials: Controversies, pitfalls AstraZeneca-Oxford Covid-19 vaccine faced – world news

Researchers at Oxford University created a vaccine using adenovirus, a virus that causes colds in chimpanzees. They genetically alter the virus to have a gene for the coronavirus protein, and researchers say they will train a person’s immune system to recognize the actual coronavirus. Adenovirus-based vaccines are not anomalous. Russia’s Sputnik-V and Chinese vaccines also used similar techniques, but neither of them published reliable results or submitted the findings for peer review. Therefore, their effectiveness is unknown. The adenovirus vaccine was also previously patented for Ebola by pharmaceutical giants Johnson and Johnson.

Why is its efficacy suspected?

In the spring of 2020, AstraZeneca and Oxford began clinical trials in the UK and later in other countries. In the first trial, the volunteers were producing antibodies and the vaccine was considered to be in the right place. However, on November 23, the vaccine team reported that two sets of volunteers received two types of vaccinations due to an error. The group that received the vaccine twice had an efficacy of 62{74ca91e3bee52d91843c282edd75c0800a88a3d8744a3a1c83b7ba867058fc3c}, and the group who received the full dose after accidentally receiving a half shot had an efficacy of 90{74ca91e3bee52d91843c282edd75c0800a88a3d8744a3a1c83b7ba867058fc3c}. Reuters reported that researchers were embarrassed when the common side effects of fatigue, arm pain, and headache became much milder than expected. Upon confirmation, they found that the group received only half of the initial vaccination dose. No one knows what caused this anomaly, and researchers attributed it to a lucky coincidence.

What effect did the dosing error have?

The main problem seems to be in the limited size of the group that received half the dose and the full dose. It was significantly smaller than the group that received two full doses and did not include participants over the age of 55; this controversy led AstraZeneca to unveil a new global trial in November for a half-dose/full-dose vaccine.

However, the researchers found that, regardless of the dosing regimen, none of the trial participants showed severe coronavirus symptoms or were hospitalized for disease after only one vaccination, and both elderly and young participants had similar immune responses to the jab. Of the total 23,000 participants for which results were reported, less than 2,800 received the initial half dose. That’s a very small sample based on efficacy results.

During the phase 3 trial, some neurological problems also occurred with volunteers in the United States and India. The U.S. Food and Drug Administration did not directly link the vaccine to the problem, but the developer had to pay attention. Even in the final report, AstraZeneca and Oxford said that the vaccines in the trial group did not cause serious safety concerns.

What happens compared to other vaccines?

The Oxford vaccine does not require storage and transportation at cryogenic temperatures like Pfizer/Bioentech. It can be easily stored for up to 5 days in a regular medical refrigerator from 2C-8C, making it a more practical and cost-intensive option in tropical countries. What’s more, the Oxford vaccine is much cheaper than the Pfizer vaccine, which costs about $3 to $4 per dose and costs about $20.