HOW MIGHT A SUCCESSFUL VACCINE WORK?

■ VIEWED through a powerful microscope, the new coronavirus looks round and has spikes on its surface, which bind to human cells and allow the virus to gain entry. A vaccine called mRNA-1273 is designed to prime the immune system to attack the protein that makes up the spikes — thereby killing the virus. This is the first of just two vaccines to go into human trials so far, and is being tested in the U.S.

■ THE second is Ad5-nCoV, developed in China. It is being injected into 108 healthy patients to see if it kick-starts their immune systems to produce the infection-fighting cells that can destroy the virus. It uses a ‘disarmed’ cold virus — called adenovirus — to carry a version of the spike protein into the body, so that the immune system can register it as an invader and, should it later come into contact with coronavirus, launch an attack.

■ AT THE University of Oxford, scientists are taking a similar approach, producing a vaccine to target the spike protein. Human tests are expected to begin in the next few weeks.

■ INOVIO Pharmaceuticals in the U.S. is also developing a vaccine to stimulate an immune system response, but this one can be delivered through the skin using a device

resembling a hairdryer. It has two needles that penetrate into muscle and fire electrical impulses to force open ‘pores’ on immune system cells in the area. A third needle then injects the vaccine, which sneaks through the pores. Human trials are due to start in April.

■ ISRAELI scientists are tinkering with an oral vaccine they developed for bronchitis in poultry. They predict they can mass-produce this within months, after finding that the strain used to make the vaccine is genetically very similar to the coronavirus. Researchers are now working to fine-tune the vaccine before it can be tested in humans.