How the Sinopharm Covid-19 Vaccine Works

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How the Sinopharm Covid-19 Vaccine Works

In early 2020, the Beijing Institute of Biological Products created an inactivated coronavirus vaccine called BBIBP-CorV. It was later included in clinical trials by the state-owned Chinese company Sinopharm. On December 30th, Sinopharm announced that the vaccine was 79.34 percent effective. The vaccine is currently used in Bahrain and the United Arab Emirates. Sinopharm has also applied for approval from the Chinese government.

A coronavirus vaccine

BBIBP-CorV teaches the immune system to produce antibodies against the SARS-CoV-2 coronavirus. The antibodies bind to viral proteins, such as the so-called spike proteins, which examine their surface.

To create BBIBP-CorV, Beijing Institute researchers received three variants of the coronavirus from patients in Chinese hospitals. They chose one of the variants because it could multiply rapidly in monkey kidney cells that were grown in bioreactor tanks.

Kill the virus

After the researchers made large amounts of coronavirus, they doused them with a chemical called beta-propiolactone. The compound deactivated the coronaviruses by binding to their genes. The inactivated corona viruses could no longer replicate. But their proteins, including the tip, remained intact.

The researchers then peeled off the inactivated viruses and mixed them with a tiny amount of an aluminum-based compound called an adjuvant. Adjuvants stimulate the immune system to increase its response to a vaccine.

Inactivated viruses have been used for over a century. Jonas Salk used them to make his polio vaccine in the 1950s and they are the basis for vaccines against other diseases such as rabies and hepatitis A.

Invitation to the immune response

Since the coronaviruses in BBIBP-CorV are dead, they can be injected into the arm without causing Covid-19. In the body, some of the inactivated viruses are swallowed by a type of immune cell called an antigen-presenting cell.

Present

Virus protein

Fragments

Present

Virus protein

Fragments

Present

Virus protein

Fragments

The antigen presenting cell tears up the coronavirus and shows some of its fragments on its surface. A so-called helper T cell can detect the fragment. When the fragment fits into one of its surface proteins, the T cell is activated and can help recruit other immune cells to respond to the vaccine.

Make antibodies

Another type of immune cell called a B cell can also encounter the inactivated coronavirus. B cells have surface proteins in a variety of shapes, and some may be the right shape to attach to the coronavirus. When a B-cell locks into place, it can ingest some or all of the virus and present coronavirus fragments on its surface.

A helper T cell activated against the coronavirus can bind to the same fragment. In this case, the B cell is also activated. It multiplies and releases antibodies that are the same shape as their surface proteins.

Matching

Surface proteins

Matching

Surface proteins

Matching

Surface proteins

Matching

Surface proteins

Matching

Surface proteins

Matching

Surface proteins

Matching

surface

Proteins

Matching

surface

Proteins

Matching

surface

Proteins

Matching

Surface proteins

Matching

Surface proteins

Matching

Surface proteins

Stop the virus

Once vaccinated with BBIBP-CorV, the immune system can respond to infection with live coronaviruses. B cells produce antibodies that adhere to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells. Other types of antibodies can block the virus in different ways.

Memory of the virus

Sinopharm's clinical studies have shown that BBIBP-CorV can protect people from Covid-19. But nobody can say how long this protection will last. It is possible that antibody levels may drop over the months. But the immune system also contains special cells, so-called memory B cells, which can store information about the coronavirus for years or even decades.

Vaccination schedule

January 2020 Sinopharm begins developing an inactivated vaccine against the coronavirus.

June Researchers report that the vaccine has shown promising results in monkeys. A phase 1/2 study shows the vaccine does not cause serious side effects and allows people to make antibodies against the coronavirus.

A Sinopharm production facility in Beijing.Zhang Yuwei / Xinhua, via Associated Press

July A phase 3 study is starting in the United Arab Emirates.

August Phase 3 trials are starting in Morocco and Peru.

Preparing a Sinopharm dose in Lima, Peru.Ernesto Benavides / Agence France-Presse

September 14th The U.A.E. grants emergency clearance for Sinopharm's vaccine for use by healthcare workers. Government officials and others are starting to get it.

November Sinopharm chairman says nearly a million people in China have received Sinopharm vaccines.

November 3rd The ruler of Dubai, Sheikh Mohammed bin Rashid al-Maktoum, announces that he has received the vaccine.

Sheikh Mohammed before receiving the vaccine.Agence France-Presse

9th of December The U.A.E. gives BBIBP-CorV full approval and announces an effectiveness rate of 86 percent. However, the government did not release any details with their announcement and left unclear how they reached their conclusions.

13th December Bahrain also approves the vaccine.

Vials with the Sinopharm vaccine in a packaging plant.Zhang Yuwei / Xinhua, via Associated Press

30th of December Sinopharm announces that the vaccine is 79.34 percent effective. The company has not yet published the detailed results of its phase 3 study.


Sources: National Center for Information on Biotechnology; Science; The lancet; Lynda Coughlan, University of Maryland Medical School; Jenna Guthmiller, University of Chicago.

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