The biggest vaccination campaign in history is underway, with nearly 30 million doses administered every day. How exactly do these vaccines fight Covid-19 – and how large is their impact?
How many Covid-19 vaccines are there?
There are currently 15 vaccines that have been authorised around the globe. All of these are in use in at least one country. The world’s leading vaccines are Pfizer-BioNTech, Moderna and Gamaleya. All of them are being deployed in over 60 countries.
Researchers are also currently testing 91 vaccines in clinical trials on humans. Twenty seven have reached the final stages of testing.
Why are there so many in development?
Vaccines require research and testing before they are found to be both safe and effective. According to the World Health Organisation, of all the vaccines studied in the lab, roughly 7 out of every 100 are considered good enough to move to clinical trials on humans.
Of the vaccines that do make it that far, 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.
How do they work?
Put simply, a vaccine trains the immune system. When a new pathogen or disease enters the body, it introduces a new antigen. For each new antigen, the immune system needs to build a specific antibody that grabs onto the antigen and defeats the pathogen. Once the immune system has created the antibodies once, it can produce them much faster if they are needed again. In this way, the body builds a natural immunity to a disease.
A vaccine is a tiny weakened, non-dangerous fragment of the organism and includes part of the antigen. It contains enough information that our body can learn to build the specific antibody. Then, if the body encounters the real antigen later, it has already learnt how to defeat it.
What is the difference between them?
There are three main approaches to designing a vaccine: using a whole virus, using just the parts of the germ that triggers the immune system or using genetic material.
CoronaVac is is an example of an inactivated vaccine. It is made using dead samples of SARS-CoV-2.
Pfizer-BioNTech, Moderna and Oxford-AstraZeneca are all based on the virus’s genetic material. The body uses it to create the spike protein for the immune system to attack. The Oxford vaccine uses double-stranded DNA. Pfizer and Moderna store instructions in single-stranded RNA – a technique never used before in vaccine development.
Do they work against new variants?
Not to worry! Experts agree that most variants do not affect how effective a vaccine is. A study in the last week has found that Pfizer and AstraZeneca jabs are “highly effective” against the fast-spreading Indian variant. But even in the worst-case scenario, now that we have the vaccines, they can be redesigned and tweaked to be a better match in a matter of weeks.
What is herd immunity?
This is when a high proportion of the population is immune to a disease. It is the best method to protect vulnerable people. Not everybody can be vaccinated – some have health conditions or allergies. But if many people are vaccinated, the pathogen has a harder time circulating, protecting even those unable to get the vaccine.
Herd immunity has been achieved in dozens of countries with illnesses like polio. In 1980, smallpox was completely eradicated after a successful vaccine programme. Experts say this can be done with Covid-19 – but only once enough people are protected globally.
- Should it be compulsory to have a Covid-19 jab?
- As a group, film your own public service announcement to encourage people to take the vaccine.
- The German company BioNTech partnered with pharmaceutical company Pfizer to create vaccine BNT162b2. In trials, it has proved over 90% effective.
- A Massachusetts-based vaccine developer created mRNA-1273. It uses the same technology as the Pfizer vaccine.
- Also known as Sputnik-V, Gamaleya is Russia’s main vaccine.
- A tiny organism that invades the body and makes it unwell.
- A molecule that is expressed by a bacteria or virus (pathogen). It usually appears on the surface of a cell.
- A Y-shaped protein that sticks to the surface of bacteria and viruses. They are designed to attack only one kind of antigen.
- Developed by Chinese company Sinovac, it is approved for use in China and for emergency use in more than 12 other countries.
- The virus that causes Covid-19.
- The University of Oxford partnered with British-Swedish company AstraZeneca to develop a vaccine known as ChAdOxl nCoV-19.
- Short for ribonucleic acid. Unlike DNA, it only contains one strand.
- An infectious disease that affected children all over the world. It left victims paralysed or unable to move their muscles.
- For centuries, the disease killed millions across the globe every year. It was completely eraticated in 1980 by the World Health Organisation.