The Vaccine Saga: The blood clot fright!

By Dr Vinod RMT Balasubramaniam
Molecular virologist
Jeffrey Cheah School of Medicine and Health Sciences

AstraZeneca is made from a weakened version of a common cold virus known as an adenovirus from chimpanzees. It has been modified to contain genetic material shared by the coronavirus - although it can't cause the illness. Once injected, it teaches the body's immune system how to fight the actual virus.

Due to adverse side effects from the vaccine, which was first seen in the United Kingdom, there have been concerns regarding its usage. Health regulators in the UK found 242 clotting cases and 49 deaths after an estimated 28.5 million AstraZeneca vaccine doses were administered across the UK up to 28 April.

For the vast majority of people, the benefits of the AstraZeneca vaccine outweighs its risk. It has prevented severe symptoms, hospitalisation and death from COVID-19 in vaccinated people. The incidence of the blood clot is somewhere around 0.0004%, which is extremely rare.

When a person is immune to a disease, they can act as a barrier to slow down or prevent disease transmission to other people. When people in a population become resistant against disease, and the disease is no longer prevalent in the community, it is called a herd immunity threshold (HIT).

The duration of immunity (protection against disease) varies with different diseases and different vaccines. Lifelong immunity is not always provided by either natural infection (getting the disease) or vaccination. The recommended timing of vaccine doses aims to achieve the best immune protection to cover the period in life when vulnerability to the disease is highest. Many vaccines used today are relatively new, and data concerning the length of time they give protection is continually updated.

We are in the midst of one of the worst pandemics in the history of humanity. Our only salvation from this disease is a vaccine. And the only way to stop more variants/mutants from appearing is by vaccinating as many people as possible until we reach the herd immunity threshold. All vaccines work! We can't afford the time to choose the vaccine we want as the clock is ticking.