Coronavirus vaccines leap through safety trials — but which will work is anybody’s guess

Coronavirus vaccines leap through safety trials — but which will work is anybody’s guess



The University of Oxford’s candidate vaccine against COVID-19 is being tested in South Africa, the United Kingdom and Brazil. (Siphiwe Sibeko/AFP via Getty)

Inside the four vaccine front-runners

A flood of data from the first human coronavirus-vaccine trials have revealed four promising candidates. All work by exposing the immune system to the virus’s spike protein, in hopes of provoking a reaction against a real infection in the future.

• A ‘viral vector’ vaccine from the University of Oxford and AstraZeneca in the United Kingdom. It harnesses a genetically modified adenovirus that causes colds in chimpanzees that expresses the coronavirus spike protein.
• A similar approach from CanSino Biologics in China, which uses a modified human adenovirus instead.
• An RNA-based vaccine from Pfizer and German company BioNTech. It relies on messenger RNA that synthesizes a crucial part of the coronavirus called the receptor-binding domain.
• Another RNA vaccine from US company Moderna in collaboration with the US National Institute of Allergy and Infectious Disease.

All four vaccine-makers said that their vaccines elicited some kind of immune response in people, broadly similar to that seen in recovered patients, without serious side effects. Scientists caution against picking a favourite, yet. “The data are so early and so preliminary, one thing to avoid is saying one is better at this stage because we just don’t know,” says immunologist Rafi Ahmed. Next: the completion of phase III trials. These will reveal whether a vaccine triggers an immune response that protects against COVID-19 — a process that is not yet well understood.
Nature | 6 min read