Here’s How the 3 Main COVID-19 Vaccines Work Simplified for You

In 1796, the British doctor Edward Jenner developed a vaccine to combat the deadly smallpox virus.

It was the first vaccine ever created to prevent infection from a contagious disease.

Fast forward over 200 years, and a vaccine is still our only hope against the devastating Covid-19 pandemic.

Scientists around the globe have achieved the remarkable feat of developing a coronavirus vaccine in less than a year after the virus first emerged in the Chinese city of Wuhan.

According to the Centers for Disease Control and Prevention, there are currently three main types of Covid-19 vaccines.

These vaccines are already in use in several countries, as more nations prepare to approve and receive large shipments of the vaccine, to hopefully put an end to the pandemic.

So, how exactly do these inoculations work?

Before we get to that, we have to understand what a vaccine is.

Training the Body’s Immune System to Recognise Threats

A vaccine is a type of medicine that trains the body’s immune system so it can fight a disease it has not come into contact with before.

Vaccines are designed to prevent disease, rather than treat a disease once you have caught it.

Every time a virus or bacterium invades our beautiful bodies, our immune system has to fight it off.

But not everyone is strong enough to fight a virus off, of course. This is why we have vaccines.

A vaccine contains a weakened or killed form of the virus that causes a particular disease so that your immune system can easily fight it off and create antibodies, making you immune to the virus in the future.

So, a vaccine essentially provides a shortcut by helping your immune system learn to recognise a specific threat by tricking it into thinking it’s under attack.

The three vaccines currently in use are mRNA, Adenovirus, and protein vaccines.

mRNA Vaccines

Moderna and Pfizer-BioNTech’s Covid-19 vaccines are currently in use in several countries, including the US and the UK.

They are both mRNA (or RNA) vaccines, meaning they use a synthetic copy of a natural chemical called messenger RNA (mRNA) to produce an immune response.

According to The New York Times, the coronavirus is studded with proteins that it uses to enter human cells.

These are called spike proteins. 

As previously mentioned, vaccines have to “train” our bodies to recognise threats like viruses.

That’s why mRNA vaccines transfer molecules of synthetic RNA into our human cells, instructing them to produce the spike protein unique to the coronavirus.

Once our muscle cells produce the protein, it triggers the immune system to attack it.

Thus, if we contract the coronavirus in the future, the body will “remember” how to fight it.

Both Moderna and Pfizer-BioNTech’s Covid-19 vaccines have been shown to be around 95% effective, far surpassing expectations.

One downside of these mRNA vaccines is their fragility.

They will quickly fall apart at room temperature, which is why both Moderna and Pfizer-BioNTech’s vaccines have to be kept at extremely low temperatures.

Moderna’s vaccine needs to be stored at -20°C and Pfizer’s vaccine at -70°C, which may present logistical issues for some countries.

The advantage of an mRNA vaccine is its simplicity, as it can be produced as soon as the genetic sequence of the pathogen is determined, according to Futurity. 

Adenovirus (Vector) Vaccines 

The second type of vaccine currently in use is the Adenovirus or Vector vaccine.

These vaccines use a chemically weakened virus to transport pieces of the pathogen in order to trigger an immune response.

China and Russia have already begun using their CanSino vaccine and Gamaleya vaccine respectively – both Adenovirus vaccines – though the world hasn’t formally recognised these vaccines as safe yet, because no data from their clinical trials have been released.

Just like the mRNA vaccine, an adenovirus vaccine is designed to train the body’s immune system to recognise the coronavirus so it can fight it off effectively.

But the difference lies in how they get your cells to build the spike proteins which resemble that of the coronavirus’.

While the mRNA is wrapped in oily bubbles made of lipid nanoparticles for protection, the adenovirus vaccines use another virus to release the genes that encode the coronavirus’ spike proteins.

Basically, both vaccines do the same thing, but take a different mode of “transport”.

Now, your eyes might widen at hearing that another live virus will be introduced into your system, but there’s no need to worry.

Adenoviruses are a family of viruses, most of which don’t cause any known diseases except mild symptoms, such as those associated with the common cold.

Scientists have chosen particular strains of Adenoviruses that don’t cause any disease to deliver the vaccine against the coronavirus.

Protein Subunit Vaccines 

The only protein subunit vaccine currently in use is the Vector Institute’s Covid-19 vaccine in Russia.

Instead of the entire virus, a protein subunit vaccine contains harmless components (proteins) of the virus, which in this case, is the coronavirus.

These harmless components will stimulate an immune response once introduced into your system.

While protein vaccines are safer and easier to produce, it often requires the incorporation of additional components (adjuvants) to boost immunity, as the antigens alone are not enough to induce adequate long-term immunity.

So, when will it be our turn to get a vaccine?

Vaccine to Arrive in Singapore By End-December

The Health Sciences Authority (HSA) recently approved Pfizer-BioNTech’s vaccine, which is already in use in Britain and the US.

The government has also signed Advance Purchase Agreements with Moderna and Sinovac, and is in discussions with a few other pharmaceutical companies.

The first batch of Pfizer-BioNTech vaccines is expected to arrive in Singapore by end-December 2020.

Subsequent batches from the three companies will arrive in 2021.

While three recipients of Pfizer-BioNTech’s vaccine have experienced anaphylactic reactions, there have been no other serious, adverse reactions.

Side effects such as fatigue, muscle pain, chills, and fever are common, but these are simply signs that the vaccine is working, as your body is fighting off its invader.

With the exception of pregnant women, the immuno-compromised, and those under 16, everyone here is strongly encouraged to get the vaccine, but it remains voluntary.

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