How AstraZeneca (AZD1222) Covid-19 Vaccine is Used
Introduction
By collaboration between the University of Oxford with the British-Swedish, company named AstraZeneca. In addition, they collaborated to develop a vaccine known as AZD1222 to cure Covid-19 patients.
During Clinical, trials it was founded that found that the vaccine had an efficiency of 82% when two of its doses were given within twelve weeks apart. There was some uncertainty regarding trial results, Britain authorized the vaccine for emergency use in December, and India authorized a version of the vaccine called Covishield on January 3.
The vaccine is based on the virus’s genetic instructions for building the spike protein.
However, as compared to Pfizer-BioNTech and Moderna vaccines, which store the instructions in single-stranded RNA, the AstraZeneca vaccine uses double-stranded DNA.
Adenovirus Used in DNA
According to research, the researchers added the gene for the coronavirus spike protein to another virus called an adenovirus. Adenoviruses are common viruses that typically cause colds and you can say some flu-like symptoms.
AstraZeneca's team used a modified version of a chimpanzee adenovirus, known as ChAdOx1. It can enter cells, but it cannot replicate inside them. AZD1222 comes out of decades of research on adenovirus-based vaccines. In July, a vaccine was approved for general use for Ebola, made by Johnson and Johnson. Advanced.
This AstraZeneca vaccine for Covid-19 is stronger as compared to vaccines from Pfizer and Moderna. The genetic material that is present inside can be protected with a coat of protein of adenovirus whereas; DNA is not as breakable as RNA.
As a result, the AstraZeneca vaccine does not have to stay frozen but this vaccine needs a temperature of 2–8°C to get stored in a refrigerator.
How to use Vaccine
When the vaccine is injected into a person’s arm, the adenoviruses bump into cells and latch onto proteins on their surface. The cell overtakes the virus in form of an ab bubble and takes it inside. When the adenovirus comes out from the bubble and travels to the nucleus, the chamber where the cell’s DNA is stored.
Its DNA is pushed into the nucleus. The adenovirus is pulled off so it can’t make copies of itself, but the gene for the coronavirus spike protein can be read by the cell and copied into a molecule called mRNA
Proteins of Spike
The messenger RNA leaves the nucleus, and the cell’s molecules read its sequence and begin assembling spike proteins. Some of the spike proteins produced by the cell form spikes that migrate to its surface and stick out their tips.
The vaccinated cells also break up some of the proteins into different sets, which they present on their surface. These spikes and their protein sets can then be recognized by the immune system. Adenovirus also provokes the immune system by switching on the cell’s alarm systems.
The cell sends out warning signals to activate immune cells for future use. Due to this AstraZeneca, vaccine causes the immune system to react more strongly to the spike proteins.
Intruder
When a vaccinated cell dies, trash contains spike proteins and a set of proteins that can be taken up by a type of immune cell called an antigen-presenting cell. The cell presents fragments of the spike protein on its surface.
When other cells called T cells detect these sets of proteins, the helper T cells can raise the alarm and help marshal other immune cells to fight the infection.
Antibodies
Like other immune cells, named B cells this may bump into the coronavirus spikes on the surface of vaccinated cells. A few of the B cells may be able to lock onto the spike proteins. If these B cells are then activated by helper T cells, they will start to boost and flow out antibodies that target the spike protein.
Infected Cells
APCs cells can also activate another type of immune cell called T cell, which is very dangerous to seek out and destroy any Covid-19 infected cells that display the spike protein fragments on their surfaces.
Conclusion
AstraZeneca vaccine requires two doses with a timeline of four weeks apart, to prime the immune system to fight off the coronavirus. During the clinical trial of the vaccine, the researchers accidentally gave some volunteers only half a dose.
Surprisingly, the combination in which the first dose was only 1/2 strength was 90% effective in preventing Covid-19 in the clinical trial. In contrast, the combination of two full-dose shots led to just 62% effectiveness.
The researchers get doubtful that lowering the first dose did a better job of copying the experience of infection, promoting a stronger immune response when the second dose was given.
The pandemic is very new for the whole world and vaccine is also very, researchers do not know how long its protection might last. It is possible that in the months after vaccination, the number of antibodies and killer T cells will drop.
However, the immune system also contains special cells called memory B cells and memory T cells that might retain information about the coronavirus for years or even decades.
