The coronavirus vaccines

The injection developed by Oxford University and made by AstraZeneca is a conventional vaccine, using a harmless, weakened version of a common virus that causes colds in chimpanzees. Researchers have previously used this technology to produce vaccines against pathogens including flu, Zika and Middle East Respiratory Syndrome (Mers).

The Oxford team are now using the “harmless chimp cold virus to deliver genetic information from the coronavirus to human cells to trigger the production of the spike protein” that kick-starts the immune response, says The Guardian.

Unlike most vaccines, which rely on weakened or inactivated parts of the virus to provoke an immune response in their recipients, the one developed by BioNTech and made by Pfizer is synthetic.

The new vaccine is made using messenger ribonucleic acid (also known as messenger RNA or mRNA). Whereas DNA is where we store our genetic information, mRNA - as its name suggests - transmits information and puts DNA’s instructions into action.

In the case of the Pfizer vaccine, the researchers synthesised a form of mRNA that will “cause our own cells to make a viral protein” from the Covid-19 coronavirus, says The New York Times. The protein is harmless in isolation, but prompts the human immune system to “make antibodies and immune cells that can recognise the protein quickly and deliver a swift attack”.

Like the Pfizer vaccine, the drug made by Moderna relies on mRNA to generate an immune response.

This new technique allows researchers to “eliminate much of the manufacturing process because rather than having viral proteins injected, the human body uses the instructions to manufacture viral proteins itself”, says The Conversation. Once developed, it can also be manufactured far more quickly than traditional immunisations.

Until 2020, however, the process had never successfully been harnessed to produce a safe, effective vaccine.

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.

But with so many different vaccines in production, questions are undoubtedly going to be raised, such as can I still have a vaccine if I have been involved in a trial testing other versions? And, what if I’ve already had Covid – do I still need a vaccine? A basic understanding of immunology can answer all these questions...

The UK’s Vaccine Task Force is planning to test whether a combination of two different coronavirus vaccinations could provide more effective protection than a double injection of just one.

“Instead of a first shot of the Pfizer vaccine followed by a booster three weeks later, the trials will look at using Pfizer for the first shot then Oxford for the second... or vice versa,” The Times reports.