Coronavirus vaccine: Which candidates are the most promising?


The race to find a Covid-19 vaccine continues to gather pace at lightning speed, with a total of 26 candidates currently in the clinical evaluation stage of development, according to the World Health Organisation.

A process that typically takes between 10 and 15 years, vaccine production is being worked on by governments and leading pharmaceutical companies, who are hoping to find a vaccine— and a way out of the coronavirus pandemic — by the end of the year.

Of the 26 candidates that are being trialled on humans, only a handful of these have entered into phase three of testing — the final stage before regulatory approval is then secured (or denied).

Oxford University and AstraZeneca

Name: ChAdOx1 nCoV-19

How does it work?

Oxford’s candidate is a viral vector vaccine and is made from a genetically engineered virus that causes the common cold in chimpanzees. It has been weakened to ensure it does not trigger any disease in humans and is modified to express the spike protein seen on Sars-CoV-2 – the tool used by the virus to invade human cells.

When this genetic material enters the human body, it “helps teach the immune system to recognise the Sars-CoV-2 virus”, according to professor Andrew Pollard, the study lead.


Name: CoronaVac

How does it work?

The Chinese biopharmaceutical has developed an inactivated vaccine that uses a non-infectious version of the virus to provoke an immune response.


Name: mRNA-1273

How does it work?

The American biotech firm is one of a handful of companies attempting to develop a mRNA vaccine. Whereas the more traditional methods of vaccine development introduce an inactivated or weakened form of Sars-CoV-2 to the body, the mRNA approach delivers genetic material to human cells that instruct them to make the ‘spike’ proteins seen on the surface of the coronavirus.

An immune cell then perceives the spike proteins as if the body has been infected. It kicks off a sequence of events that results in the creation of antibodies and other defences.

No mRNA vaccine has ever been approved for an infectious disease, and Moderna has never brought a product to market. But proponents of the vaccine say it could be easier and quicker to mass produce, as only small quantities of the virus are used for gene sequencing and vaccine testing.

Pfizer and BioNTech

Name: BNT162b2

How does it work?

US drugmaker Pfizer and German biotech firm BioNTech are collaborating to design a mRNA vaccine which makes use of the same technology adopted by Moderna.

Full detail here of all the vaccines here