Corona vaccines ... how do they work? What is the difference between them?

Arab Weather - Since the Corona virus epidemic began sweeping the world, dozens of vaccines have entered clinical trials during the year 2020, and some have been allowed to use after they have met all the necessary criteria, while their developers continue to collect data to verify their effectiveness and safety.

In this article, we provide you with a quick guide to the emerging coronavirus (COVID-19 ) vaccines that are now being used around the world.

1. Pfizer Bionic vaccine ( Pfizer-BioNTech )

A large study found that a vaccine developed by Pfizer and German biotechnology company BioNTech is 95% effective in preventing COVID-19 .

The vaccine is given in two doses , three weeks apart, and the vaccine must be stored at a temperature below 70 degrees Celsius.

• Starting the use of the vaccine around the world

On December 11, 2020, the Pfizer-BioNTech vaccine became the first coronavirus vaccine to be licensed for use by the U.S. Food and Drug Administration ( FDA ).

Several other countries have also permitted the use of the vaccine , including the United Kingdom, Argentina, Chile and Singapore, and the European Union followed suit on December 21.

Bahrain, Canada, Saudi Arabia and Switzerland fully approved the use of the vaccine. On January 25, Australia gave the vaccine "provisional approval" for use in people aged 16 and over.

On March 31, Pfizer announced that the vaccine was 100% effective in preventing Coronavirus in children ages 12 to 15 in late-stage clinical trials.

• How the Pfizer vaccine works

The Pfizer vaccine uses a molecule called mRNA as its base. The mRNA molecule is a "messenger" nucleic acid present naturally in all cells, and the molecule contains instructions for building specific proteins. In the case of this vaccine, the mRNA in the vaccine bears codes for the spinal protein on the surface of the Coronavirus, which the virus uses to adhere to human cells.

Once the vaccine enters the body, it directs the human cells to build antibodies against this protein to intercept the viruses before they enter the cells and multiply, and thus the immune system learns to recognize the virus and attack it.

2. Vaccine Moderna (Moderna)

The Moderna vaccine was developed by the American biotechnology company Moderna, and the National Institute of Allergy and Infectious Diseases ( NIAID ). The Moderna vaccine also uses the mRNA molecule as its basis, and its effectiveness is estimated at 94.5% in preventing the Corona virus.

The vaccine is taken in two doses , four weeks apart , and the vaccine can be stored at a temperature of 20 degrees below zero degrees Celsius.

• Starting the use of the vaccine around the world

The US Food and Drug Administration authorized the use of the Moderna vaccine on December 18, the European Medicines Agency authorized the use of the vaccine in January, and Canada approved the vaccine in full on December 23.

• How does Moderna vaccine work?

The mechanism of action of moderna vaccine with the mechanism of the mRNA-based Pfizer vaccine to generate antibodies.

3. vaccine Oxford AstraZeneca (AstraZeneca)

The vaccine developed by the University of Oxford and the pharmaceutical company AstraZeneca is estimated to be approximately 70% effective in preventing corona virus, however, clinical trials have shown that adjusting the dose enhances this effectiveness.

In people who received two full doses , 28 days apart, the vaccine was 62% effective. For those who received a half dose followed by a full dose , the vaccine was 90% effective, according to early analyzes. However, clinical trial participants who got half a dose did so by mistake, and some scientists had doubts about these early results.

• Starting the use of the vaccine around the world

The United Kingdom and Argentina authorized the Oxford-AstraZeneca vaccine for use in late December, India and Mexico approved the vaccine for use in January, the European Medicines Agency of the European Union authorized the use of the vaccine for adults on January 29, and Canada approved the vaccine on February 26.

However, dozens of countries temporarily stopped using the vaccine when reports surfaced of blood clots and abnormal bleeding among some of the vaccinated people. A subsequent review by the European Medicines Agency of the European Union concluded that the vaccine does not increase the incidence of blood clots in general, but the committee did not rule out a link between it and the occurrence of some rare coagulation disorders.

The committee then launched a deeper investigation into these rare clotting events and found that they are related to the vaccine , although it is not known exactly how the vaccine causes thrombosis, and the committee recommended that blood clots and a low platelet count be listed as possible side effects of the vaccine.

• Mechanism of action of the AstraZeneca vaccine

AstraZeneca vaccine contains a weak version of adenovirus , which is a common cold virus that naturally infects chimpanzees. Scientists modified the virus so that it could not reproduce in human cells, then they added the genes that code for the spinal protein found on the surface of the Corona virus, and when the vaccine enters the body and reaches the cells, it delivers these spiny protein genes, which cells use to build the spiky protein itself, leading to the presence Spiky proteins trigger an immune response.

4. Vaccine Johnson & Johnson (Johnson & Johnson)

Showed vaccine Johnson & Johnson , which was developed by Janssen Inc. (Janssen) overall efficiency by 72% in the US and 64% in South Africa , where Corona highly variable viruses cause infection in most cases , the new occurrence there.

In terms of its effectiveness in preventing severe symptoms of the disease, the vaccine has shown efficacy of 86% in the United States and 82% in South Africa. The vaccine showed 100% effectiveness in both sites against hospitalization and death. This means that no person who was given the vaccine during clinical trials died of infection with the Coronavirus, or required hospitalization within 28 days after vaccination.

The vaccine can be stored for months at normal refrigerator temperatures .

• Starting the use of the vaccine around the world

On February 25, after analyzes by the Food and Drug Administration, Bahrain was the first country to allow the use of the vaccine, and the United States authorized the vaccine for use on February 27.

• The mechanism of action of the Johnson & Johnson vaccine

Similar to the AstraZeneca vaccine, the Johnson & Johnson vaccine contains a weak version of the common cold virus (adenovirus). Scientists have genetically modified the adenovirus, so it can no longer infect human cells, and then they added the genes that code for the spinal protein of the Corona virus.

Once the vaccine enters the body, the vaccine trains the immune system to recognize the spinal protein and target the Coronavirus to destroy it. It has been used Janssen (Janssen Inc.) , a similar strategy to develop a vaccine current Ebola virus.

5. Vaccine Sinovarm (Sinopharm)

Sinopharm Corporation (the state-owned China National Pharmaceutical Industries Group) has developed two anti-coropavirus vaccines, one of which was developed in cooperation with the Beijing Institute of Biological Products, and it is an inactive corona virus vaccine, and it is a modified version of the ( SARS-CoV-2 ) virus. It can reproduce.

In late December, Sinopharma announced that the vaccine, called BBIBP-CorV , was more than 79% effective, according to preliminary data from late-stage clinical trials, but the company did not release the data mentioned.

The vaccine is given in two doses , three weeks apart.

• Starting the use of the vaccine around the world

In the summer of 2020, China granted Sinopharma a permit to vaccinate construction workers, diplomats and students with either vaccine, and the company’s president said nearly a million people had received the vaccine by November.

The United Arab Emirates allowed the use of the vaccine in September, and then fully approved the vaccine in December. Bahrain and China fully approved the vaccine in December, and Egypt allowed its use in January 2021.

• Sinopharm II Vaccine

The Synopharm II vaccine, developed by the Wuhan Institute of Biological Products, uses an inactivated Coronavirus as a base . The vaccine has been approved for use in China and the United Arab Emirates, but little is known about its effectiveness.