By Kat McGregor
Coronavirus (Covid-19) was first reported just over a year ago, and is already responsible for more than 2 million deaths globally. Thanks to scientists’ incredible work, soon enough, we should see the descent of case numbers through the roll-out of vaccines across the UK and worldwide.
There are three brands of vaccines in the UK approved to protect against Covid-19: Pfizer/BioNTech, Oxford/AstraZeneca and Moderna.
But what is a vaccine?
Vaccines are simple, safe injections that protect against pathogens such as viruses and bacteria. They train your body’s immune system into producing antibodies – protective proteins that can recognise and latch onto specific proteins (antigens) of the pathogen to remove them from the body.
So why is there more than one vaccine in the UK?
When scientists are developing vaccines, there is a long process of checks to ensure they are safe for the public. These tests are so intensive that only 7 out of every 100 vaccines developed will be deemed safe.
Through the rapid development of technology and an increase in research funding, three of these vaccines have passed all necessary checks. They have been deemed safe for use by the government drug agency, the MHRA, an unprecedentedly fast turnaround.
The BBC have made a handy table (below) showing information on the types of vaccines available.
What is the difference between each vaccine?
There are three main approaches to vaccine development: using the whole micro-organism, parts of the micro-organism, or the genetic material (the instructions for making specific proteins).
The whole micro-organism approach
These are some of the oldest approaches to vaccines and involve using a whole (weakened or dead) version of the pathogen to activate an immune response in the body.
The injection of a weakened version (genetically modified by nature or scientist) of a living pathogen to offer long-term protection.
Whole bacteria or viruses that have been killed, or inactivated, so they cannot replicate. These vaccines do not cause any disease but initiate an immune response as the “shape” of the proteins remain to be identified by antibodies as foreign.
Viral vectored vaccines
The method used by Oxford/AstraZeneca. A harmless virus (the vector) delivers some genetic code for pathogenic antigens (the proteins the immune system can recognise).Researchers remove the vector’s ability to replicate so that the vaccine cannot cause disease.
The subunit approach
The most common vaccine approach used in the UK. This approach doesn’t contain a whole pathogen, but specific parts (subunits) of a virus or bacterium that the immune system needs to recognise it.
The genetic material approach
Nucleic acids: how proteins are made
DNA and RNA are nucleic acids – the instructions used to make proteins in all cells. In all cells, DNA is the first part of the instruction, which then acts as a template to produce mRNA (messenger RNA). mRNA is a blueprint for protein production.
The method used by Pfizer/BioNTech and Moderna.
These approaches are called nucleic acid vaccines. Instead of delivering whole or parts of a pathogen, they deliver parts of the antigens’ genetic instructions to cells in the body.
The human immune cells then make the antigen themselves, which can then be recognised and stimulate an immune response.
Source: your genome.org
Both Pfizer/BioNTech and Moderna vaccines are RNA based. In these vaccines, the harmless piece of mRNA injected into a person encodes the “spike protein” (found on the outside of the virus). The immune cells take up the mRNA and then begin to make and display the harmless spike proteins outside of their cell membranes. These spike antigens are recognised and removed by antibodies.
Why are the mRNA vaccines a big deal?
The Pfizer/BioNTech mRNA vaccine was the first vaccine of its kind, to pass through all clinical trials, but they are not exactly new. Human trials of cancer vaccines using the same technology have been in trials since 2011.
The speed at which MHRA passed the Pfizer and Modernavaccines was exceptional, but that is not the most exciting part of the story.
Moderna has released that, due to the massive increase in funding for mRNA vaccines, they are focusing their efforts next on a vaccine for HIV. This virus has claimed more than 30million lives, with an estimated near 40million people currently living with HIV.
The increase in understanding and technology for a vaccine against Covid-19 may lead to breakthroughs against many other global public health issues, saving millions of lives.
How do vaccines prevent illnesses?
The Covid-19 pandemic has led to the rapid development of vaccines.
Vaccines are safe and clever ways to expose our bodies to pathogens, without causing illness, and causing an immune response. Once the body has made the specific antibodies for a pathogen, some remain (literally called memory cells). These memory immune cells allow the body to react very quickly if it meets the pathogen again, preventing illness.
Once vaccinated, and with boosters, people typically remain protected against the disease for many years (and in some cases lifetimes).
Vaccines are always preferred as, instead of treating or curing a disease, they stop you from getting sick in the first place.
We’ve hoped for potential solutions to the pandemic and, just like buses, three have come along at once.