How the Sinopharm Covid-19 Vaccine Works

In early 2020, the Beijing Institute of Biological Products created an inactivated coronavirus vaccine called BBIBP-CorV. Later, the Chinese state-owned company Sinopharm subjected it to clinical trials. On December 30, Sinopharm announced that the vaccine was 79.34 percent effective. The vaccine is now used in Bahrain and the United Arab Emirates. Sinopharm has also requested approval from the Chinese government.

A vaccine made with coronavirus

BBIBP-CorV works by teaching the immune system to produce antibodies against the SARS-CoV-2 coronavirus. Antibodies stick to viral proteins, such as so-called spike proteins, that dot their surface.

To create BBIBP-CorV, researchers at the Beijing Institute obtained 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 grown in bioreactor tanks.

Kill the virus

Once the researchers produced large stocks of coronavirus, they doused them with a chemical called beta-Propiolactone. The compound disabled coronaviruses by binding to their genes. The inactivated coronaviruses could no longer replicate. But its proteins, including the spike, remained intact.

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

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

Boost an immune response

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

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

Manufacture of antibodies

Another type of immune cell, called a B cell, can also be found with the inactivated coronavirus. B cells have surface proteins in a wide variety of forms, and some may be shaped appropriately to adhere to the coronavirus. When a B cell becomes blocked, it can carry part or all of the virus inside and present coronavirus fragments on its surface.

A helper T cell activated against the coronavirus can adhere to the same fragment. When that happens, the B cell is also activated. It proliferates and spills out antibodies that have the same shape as its surface proteins.

Stop the virus

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

Remembering the virus

Sinopharm clinical trials have shown that BBIBP-CorV can protect people against Covid-19. But no one can say yet how long that protection will last. The level of antibodies may decrease over the course of months. But the immune system also contains special cells called memory B cells that can retain information about the coronavirus for years or even decades.

Vaccine timeline

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

June The researchers report that the vaccine produces promising results in monkeys. A phase 1/2 trial shows that the vaccine does not cause any serious side effects and allows people to produce antibodies against the coronavirus.

July A phase 3 trial begins in the United Arab Emirates.

August Phase 3 trials begin in Morocco and Peru.

September 14 UAE grants emergency approval for Sinopharm vaccine to be used in healthcare workers. Government officials and others are beginning to receive it.

November The Sinopharm president says that nearly one million people in China have received Sinopharm vaccines.

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

December 9 The UAE gives full approval to BBIBP-CorV, announcing that it has an 86 percent success rate. But the government did not release any details with its announcement, so it was not clear how they reached their conclusions.

December 13th Bahrain also approves the vaccine.

December 30 Sinopharm announces that the vaccine is 79.34 percent effective. The company has yet to release the detailed results of its phase 3 trial.

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

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