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 vaccine uses “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.

While most vaccines rely on weakened or inactivated parts of a virus to provoke an immune response in their recipients, the one developed by BioNTech and Pfizer is synthetic. It is made using messenger RNA, also known as mRNA, which transmits genetic information stored in our DNA.

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.

Like the Oxford vaccine, the Janssen drug uses a modified adenovirus, a harmless, engineered virus that is injected into the patient. The adenovirus DNA triggers an immune response that helps protect the body from Covid-19 infection.

“Unlike other candidates, however, major US trials have focused on its effectiveness as a single dose,” says The Telegraph. Johnson & Johnson is also conducting a second phase-three trial to look into the effects of two doses of the vaccine.

The UK is believed to have spent between £24 and £28 per dose on the Moderna jab, the Daily Mail reports. The Oxford/AstraZeneca vaccine cost the government around £3 per jab, according to the BBC, while the Pfizer/BioNTech jab has a price tag of around £15.

Health Secretary Matt Hancock has pledged to offer all adults in the UK the coronavirus vaccine by autumn as the UK continues its rollout of the life-changing jab.

Vaccinating the entire population may not be necessary, however, with some experts suggesting that concentrating on giving the jab to the most at-risk groups could mean a speedier return to normal life.

In an article published last month in the Journal of Medical Ethics, University of Oxford professor Julian Savulescu writes that “the exact percentage of the population that would need to be immune for herd immunity to be reached depends on various factors, but current estimates range up to 82%”.