Corona’s response to a new vaccine is a surprise to scientists!

The scientists were surprised by the evidence that half an initial dose of the vaccine, developed by the pharmaceutical company AstraZeneca and the University of Oxford, was more effective than the full dose, and they considered it illogical. So why might a lower dose be better than a full dose when it comes to inducing an immune response?

Andrew Pollard, director of the Oxford Vaccine Group, described the results of the phase 3 clinical trial as “intriguing.” The results showed that the vaccine was 62% effective in people who took two full doses, a month apart. However, the efficacy of the vaccine increased to 90% in another group that received half a dose first and then a full dose a month later.

“I think we all expected the two large doses to produce the best response,” Pollard said, noting that the researchers only looked at the details of the results over the weekend and will now begin to drill down into the data. “We believe that by giving a smaller first dose, we are priming the immune system differently, that we are preparing it better to respond,” he said in a short press release.

“The best result after a smaller first dose might have been because this better mimics” what happens with a real infection, “said Sarah Gilber, professor in the Nuffield Department of Medicine at the University of Oxford.

Basically, the vaccine uses a safe way to trick the immune system into thinking it is dealing with a dangerous infection, leading to an immune response and immune memory that can be activated if the body encounters the actual virus that causes the disease. disease. Gilbert told reporters: “It is possible, by giving a small amount of the vaccine at the beginning and then sticking with a large amount, that we have a better way to get the immune system to work and get the strongest immune response.”

Trojans

The AstraZeneca-Oxford vaccine uses what is known as a “viral vector,” by using genetically modified viruses to deliver gene shipments to cells and instruct them on how to fight SARS-Cove 2. “The strategy uses a vector virus like a Trojan horse … It is a complex matter and is generally achieved on an experimental level, but we do not have that possibility in the current situation, “said Colin Butter, assistant professor at the University of Lincoln.

The technology itself may be the reason why half the starting dose could give a better result, according to several scientists who have commented on the results, with the immune system using the virus as the method of administration.

“It may seem puzzling that a higher starting dose produces a lower response, but this may just be due to the residual response in some patients to the inactivated vector, a part of the chimpanzee virus that is used to deliver the vaccine payload.” said Stephen Griffin, associate professor at the University of Leeds School of Medicine. But he made it clear that this could be “easily fixed” by using the modified dose.

Pollard said the researchers will look to see if the problem is related to the quantity or quality of the immune response.

Booster dose

He added that with almost all single-dose vaccines, increasing the dose is better, and methods based on priming the immune system first may work differently, when a booster dose is given later. This is especially the case for infants and children, he said, when different numbers of initialization doses are given.

Pollard added: “I think the difference is that we are not used to dealing with an infection like the Corona virus, which adult humans have never known before.”