The race is on to find a vaccine against the new COVID-19 coronavirus. Professor Jonathan Heeney explains why a cautious approach is needed and how his team is using new technology developed for influenza and Ebola viruses to target the new infection.

It is hard now to conceive that two months ago, few people had heard of the new coronavirus. Now, the virus, which causes the disease COVID-19, has spread to every corner of the globe. The World Health Organization has officially declared the outbreak a pandemic.

With the threat of hundreds of thousands – possibly millions – of people being infected and healthcare systems becoming overwhelmed, the race is on to develop a vaccine that will protect individuals and slow the spread of the disease. But Professor Jonathan Heeney, Head of the Laboratory of Viral Zoonotics at the University of Cambridge, and one of the people working on a vaccine, says that coronaviruses present a particular challenge to vaccine developers.

Coronaviruses are named after their appearance: they are spherical objects, on the surface of which sit ‘spike’ proteins. The virus uses these spikes to attach to and invade cells in our body. Once inside, the virus uses the cell’s own machinery to help itself replicate and spread throughout the body, causing disease and allowing it to transmit onwards.

Traditionally, scientists would develop vaccines that programme the body to produce antibodies that recognise and block these spikes. But this strategy can misfire with coronaviruses due to a phenomenon known as ‘antibody-induced enhancement’ or ‘vaccine-induced enhancement’, says Heeney.

“If you make antibodies against the spike, they can end up binding to it and helping the virus invade important immune cells known as monocyte-macrophages. Rather than destroying the virus, these cells can then end up being reprogrammed by the viruses, exacerbating the immune response and making the disease much, much worse than it would otherwise be.”

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