The ManicaPost
Dr Tendai Zuze
Health Matters
IN early 2020, the Beijing Institute of Biological Products created an inactivated coronavirus vaccine called BBIBP-CorV.
This is the vaccine we now call Sinopharm and clinical trials run by the State-owned company, Sinopharm, showed that it had an efficacy rate of 79 percent and other trials have shown slightly lower figures.
Sinopharm works by teaching the immune system to make antibodies against the SARS-CoV-2 coronavirus.
The antibodies attach to viral proteins, such as the so-called spike proteins that are on its surface.
To create Sinopharm, the Beijing Institute researchers obtained three variants of the coronavirus from patients in Chinese hospitals.
They picked one of the variants because it was able to multiply quickly in monkey kidney cells grown in bioreactor tanks.
Once the researchers produced large stocks of the coronaviruses, they doused them with a chemical called beta-propiolactone.
The compound disabled the coronaviruses by bonding to their genes.
The inactivated coronaviruses could no longer replicate.
But their proteins, including spike, remained intact.
The researchers then drew off the inactivated viruses and mixed them with a tiny amount of an aluminium-based compound called an adjuvant.
Adjuvants stimulate the immune system to boost its response to a vaccine.
Inactivated viruses have been used for over a century.
Jonas Salk used them to create the polio vaccine in the 1950s, and they’re the bases for vaccines against a lot of other diseases including rabies and hepatitis.
Because the coronaviruses in Sinopharm are dead, they can be injected into the arm without causing Covid-19.
Once inside the body, some of the inactivated viruses are swallowed up by a type of immune cell called an antigen-presenting cell.
Through a complex mechanism involving various types of immune cells, your body ultimately produces antibodies against Covid-19 without you actually being infected.
Once vaccinated with Sinopharm, the immune system can respond to an infection of live coronaviruses more swiftly.
B cells produce antibodies that stick to the invaders.
Antibodies that target the spike protein can prevent the virus from entering cells.
Other kinds of antibodies may block the virus by other means.
Sinopharm’s clinical trials have demonstrated that the Sinopharm vaccine can protect people against Covid-19.
But no one can yet say how long that protection lasts.
It is possible that the level of antibodies drops over the course of months. But the immune system also contains special cells called memory B cells that might retain information about the coronavirus for years or even decades.
The sinovac vaccine is made in much the same way and works in the same way.
The vaccine, it seems, is our best option in the war against Covid-19.
It is important to remember that infected people can still get Covid-19 and spread it but when they do get sick, it is mostly just a mild illness and the chance of dying is lower.
