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Oxford coronavirus vaccine trial only has a 50% chance of success, professor leading project warns

Developing a vaccine is a complex procedure which relies on a number of lengthy steps.

But researchers racing to develop one for COVID-19 – which threatens to keep entire nations in lockdown until it can be stopped – are breaking through this stages at an unprecedented pace, scientists say.

One vaccine for rotavirus, a virus that causes deadly diarrhoea in children, took 26 years to make, the Washington Post reported, and one of its creators called this ‘pretty typical’.

Scientists must first sequence the virus they want to make a vaccine against – meaning they deconstruct it to examine its internal workings.

This process was sped up because the Chinese officials who discovered the coronavirus SARS-CoV-2 mapped the virus and shared it worldwide for free at the very start of the outbreak.

Scientists also noticed that it is almost identical to the one that causes SARS, a similar illness which hit Asia in 2002/3. This saved time because researchers already knew which areas of the virus they could target, and some had already tried to make SARS vaccines, which could work as a blueprint for tackling COVID-19.

Trials, which begin after a vaccine is painstakingly designed and produced in a laboratory, also take a long time. First, scientists must repeatedly test the vaccine on animals such as mice or monkeys. 

If it proves to be safe, this must then go on to very small human trials, then incrementally larger ones as the safety and effectiveness of it is constantly monitored.

Often, human trials take months or even years so scientists can be absolutely certain the vaccine won’t have any damaging side effects.

If there are any hiccups the researchers may have to tweak the chemical make-up of the vaccine and start again.

If things go smoothly, the vaccine can progress to the manufacturing phase and be produced en masse and sold to the people or governments who need them.

Scientists have claimed they could have a vaccine ready for COVID-19 by September this year, a break-neck pace which critics say is unlikely.

Professor Robin Shattock, an immunity expert at Imperial College London, said: ‘It’s highly unlikely that a vaccine will be available for use by September. 

‘It will be critical to build the evidence base to show a vaccine works before it’s deployed. This takes time and is dependent on seeing a difference in the number of infections between active vaccine and a placebo. 

‘The lower the transmission rate in the UK, the longer it will take to generate such data.’