There are hundreds of COVID-19 vaccines in development, and some have produced very positive results in phase III clinical trials. Currently, Pakistan has approved five vaccines for ‘emergency use’: Sinopharm, Convidecia, AstraZeneca, Russian Sputnik V and CoronaVac.
If we are ever to return to some semblance of normality, then the world’s population needs to be immune to SARS-CoV-2, the virus that causes COVID-19. However, with so many different vaccines in production, questions are undoubtedly going to be raised, such as which vaccine will be most effective against the COVID? So, how do some of the different vaccines work and compare?
Why are there so many vaccines in development?
Typically, many vaccine candidates will be evaluated before any are found to be both safe and effective. For example, of all the vaccines that are studied, roughly 7 out of every 100 will be considered good enough to move into clinical trials in humans.
Of the vaccines that do make it to clinical trials, just one in five is successful. Having lots of different vaccines in development increases the chances that there will be one or more successful vaccines that will be shown to be safe and efficacious for the intended prioritized populations.
What will vaccine do?
More than 200 COVID-19 vaccines are in development worldwide. All of them are trying to achieve the same thing – immunity to the virus, and some might also be able to stop transmission. All vaccines work by teaching our bodies to recognise and fight the pathogen in a safe way.
They do so by stimulating an immune response to an antigen, a molecule found on the virus. In the case of COVID-19, the antigen is typically the characteristic spike protein found on the surface of the virus, which it normally uses to help it invade human cells.
Vaccines that Pakistan had approved
The Drug Regulatory Authority of Pakistan (DRAP) on Friday (April 9) granted Emergency Use Authorization (EUA) to another Chinese vaccine CoronaVac.
This is the fifth coronavirus vaccine and the third Chinese vaccine to be approved for use in the country. Pakistan has granted authorization to China’s two-dose Sinopharm and single-dose Convidecia vaccine developed by the Cansino Biologicals Inc. UK’s AstraZeneca and Russian Sputnik V vaccines have also been approved by the DRAP.
Pakistan is at the moment vaccinating its healthcare workers and its elderly. But as the drive moves forward to include more age groups, it is unclear where the next tranche of vaccines will arrive.
Pakistan is expecting to receive the AstraZeneca vaccine under the COVAX programme but the shipment has been delayed due to supply constraints, after India stopped shipments to address domestic needs.
Differences between three main vaccine
Russian Sputnik V vaccine: Russia’s first approved vaccine was developed and produced entirely domestically. Researchers used common cold viruses in their vaccine prototype. Notably, they opted for two different adenovirus vectors (rAd26 and rAd5) delivered separately in a first and second dose, 21 days apart.
Using the same adenovirus for the two doses could lead to the body developing an immune response against the vector and destroying it when the second dose is administered. Two different vectors reduce the chance of this.
To make the vaccine, the adenoviruses are combined with the SARS-CoV-2 spike protein, which prompts the body to make an immune response to it. Interim results indicate that the vaccine is 91.6% effective, based on its ability to prevent symptomatic infection.
UK’s AstraZeneca vaccine: The vaccine is based on a different technology than the Moderna and Pfizer vaccines. It is made from a weakened version of a common cold virus (known as an adenovirus) from chimpanzees.
It has been modified to look more like coronavirus – although it can’t cause illness in humans. When the vaccine is injected into a patient, it prompts the immune system to start making antibodies and primes it to attack any coronavirus infection.
Something that sets this vaccine apart from the mRNA vaccines is that it appears to be very stable at relatively normal, refrigerated temperatures and it is about 63% effective against infection.
China’s Sinopharm: In early 2020, the Beijing Institute of Biological Products created an inactivated coronavirus vaccine called BBIBP-CorV. Clinical trials showed that it had an efficacy rate of 79 percent.
Once vaccinated with BBIBP-CorV, the immune system can respond to an infection of live coronaviruses. B cells produce antibodies that stick to the invaders. Antibodies that target the spike protein can prevent the virus from entering cells.
Final words
Experts have emphasized that the vaccines are safe, and despite what is often shown in the media, severe allergic reactions are rare. Though vaccination is a choice, don’t forget that vaccines have been around a long time and have saved more lives. However, don’t forget to follow the standard operating procedures (SOPs): wear a mask, practice social distancing and wash your hands often.
