Live attenuated vaccines — such as the MMR jab — work by stimulating the immune system in the same way that real Covid-19 would, but by relying on viruses unable to cause severe illness
As part of a trial to develop a vaccine against Covid-19, up to 24 people could be deliberately infected with a weakened form of coronavirus in Britain.
By the end of the year in London, a New York based company called Codagenix plans to begin experiments of its vaccine, reports Mail Online.
The jab will be of a type called a live attenuated vaccine, meaning people will be given a genetically-modified version of the coronavirus that is weaker than the real thing but still infectious.
Live attenuated vaccines — such as the MMR jab — work by stimulating the immune system in the same way that real Covid-19 would, but by relying on viruses unable to cause severe illness.
Codagenix says its vaccine was successful after a single dose in animal trials and is designed to produce immunity against various parts of the coronavirus, rather than just the 'spike protein' on the outside that many others have focused on.
This could mean it would still work even if the virus mutated. Using a live virus may enable medics to create a type of immunity that is similar to what the body would make naturally.
The trials will be held in the same facility as 'challenge trials' – in which people who have been vaccinated are deliberately exposed to the virus to test the jabs.
Codagenix has previously been reported to be joining the experiment. Details of exactly how the trial of the live attenuated vaccines will be structured have not yet been announced.
The vaccine is likely to be trialled at a 24-bed clinic in Whitechapel, East London, where participants will be quarantined, The Times reports.
The hVIVO clinic will also host 'challenge trials' of coronavirus vaccines, in which people who have had the jabs will be deliberately infected.
Although it is unclear whether Codagenix will take part in this, medical news website BioWorld reported in July that the company was planning to do so.
The company is understood to still be seeking approval from the UK's drugs regulator to go ahead with its tests.
Codagenix's vaccine will work by using a slowed-down version of the coronavirus and injecting it into participants.
Covid-19's ability to cause infection and serious disease relies on the virus multiplying rapidly inside the body before the immune system can stop it.
As it does this it can take over the lungs and blood vessels and cause the body to scramble to get rid of it, causing the tell-tale symptoms of fever and coughing, which are the immune system's attempts to cook or expel the viruses.
Codagenix's weakened form of the virus, however, can only multiply about one thousandth as fast as the wild strain (0.1 per cent of the speed).
The company developed the weaker virus by changing its genetic code using a computer programme so that it looks exactly like the wild virus.
Normally the coronavirus uses easy-to-decode sections of genes which allow it to hijack living cells and use them to multiply itself. The modified virus, however, takes significantly longer to achieve the same result.
This means it cannot get a head-start on the immune system and the body should be able to destroy it – and form a memory of how to destroy it – before it can cause illness.
Robert Coleman, the company's CEO, told The Times: 'We recode a portion of the virus's genome so that it's slowly translated by the human host.
'It's like giving American high-school students Shakespearean English – they'll read it, but they'll have a hard time.'
Codagenix intends to make its vaccine one that will be administered by a nasal spray, as the flu jab is given to children.