Covid-19 vaccine may work better as a nasal spray instead of an injection, top scientists claim

  • Oxford University and Imperial College London looking into different vaccines
  • Believe nasal spray or inhaler might be better way of priming lungs for infection 
  • Influenza vaccine is already administered to children in the UK via nasal spray 

A coronavirus vaccine may be more effective as a nasal spray or inhaler, researchers behind Britain’s most promising Covid-19 jabs claimed today.

Oxford University and Imperial College London scientists believe getting the vaccine directly into the lungs may be the best way to protect people against the respiratory infection.

Both universities are currently testing their Covid-19 jabs — administered by injection into the muscle — on thousands of humans in clinical trials, in the global race to find a way to end the pandemic.

The Oxford vaccine, leading the global race for a Covid cure, is currently being trialled on more than 10,000 people in Britain, Brazil and South Africa after moving in phase III trials.

Meanwhile the first healthy volunteer today received a ‘small dose’ of Imperial College London’s vaccine and has reported no sign effects.

Their vaccine candidates work by training the body to identify the coronavirus so it can rapidly fight off the illness before it has chance to cause an infection. Neither have been proven to work in humans yet.

But the lead scientists behind the jabs are already planning to launch a second wave of studies looking into so-called mucosal immunisation.  

Mucous membranes are protective layers of tissue that line the surfaces of internal organs, including the lungs and respiratory tract. They also coat entry points such as the nose and mouth, catching pathogens that try to get into the body.  

They form a powerful, sticky mesh that traps viruses which are trying to invade. By administering a vaccine at the entry points, it trains the mucosa to be able to identify Covid-19 and block it from getting through. 

This kind of vaccine can be given through a nasal spray, as is done for influenza in children, or inhaled. 

Professor Robin Shattock, an immunologist at Imperial, told the House of Commons Science and Technology Committee today: ‘At the moment most of the vaccines are being delivered by conventional intramuscular injection.

‘The reason is that’s the easiest and fastest to get off the starting blocks and into studies. But a number of us interested in looking at mucosal immunisation, as well. 

‘And certainly Professor Gilbert (from Oxford) and myself are already in discussion as to how me might be able to move that as a second wave of clinical study.’

Sarah Gilbert, professor of vaccinology at Oxford University, added: ‘With oral or nasal you would have much stronger mucosal response. 

‘That’s probably really important in the protection against respiratory pathogens. It’s also very difficult to study and we’re not yet very good at measuring it. 

‘But, as Professor Shattock said, we’re very interested in looking at delivery to the respiratory tract, either intranasal delivery [via a nasal spray] or aerosol delivery [using an inhaler]. 

While the Oxford vaccine was ahead in the race to protect against Covid-19, he said it could be limited by an inability to be used on the same person time and time again.

However, Professor Shattock believed it would be possible to use the Imperial jab to bolster an individual’s immunity ‘multiple times’.

Scientists around the world increasingly think booster jabs will be needed to maintain protection against the virus that causes Covid-19, as initial immunity provided by a vaccine may well fade over time.

Last Tuesday Pascal Soriot – chief executive of pharmaceutical giant AstraZeneca, which has partnered with Oxford to produce a billion doses of the jab – fuelled those fears when he said he was confident the jab would provide immunity for ‘about a year’.

Natural immunity to other coronaviruses, which cause common colds, is thought to last from several months to a couple of years.

The potential flaw with the Oxford vaccine is that it uses a harmless virus as a microscopic Trojan horse to smuggle in tiny fragments of Covid-19 coronavirus RNA – the bug’s genetic blueprint.

The recipient’s immune system learns to identify this RNA as foreign, and so creates antibodies to protect against it.

But experts fear that if a person is subjected to multiple doses of this jab, their body might ‘mistakenly’ develop an immune response to the Trojan horse virus itself – called an adenovirus – thus rendering it useless. 

As the Imperial vaccine does not use a virus as the means of smuggling in RNA, it should avoid this problem, said Prof Shattock. 

Professor Shattock said the Oxford vaccine was ‘very good to be able to give an initial immune response, but it has its limitations in that the ability to reboost immunity may be less good than other approaches’.

By contrast, he said: ‘The approach that we are developing allows you to re-boost multiple times.’ 

He continued: ‘We are often pitted against each other, or seen to be in a race against each other, but actually we are collaborating very closely together, exchanging material, and the two approaches may well be able to be used together, in a ‘prime, boost’ approach.’      

UK Health Secretary Matt Hancock last week announced frontline NHS and social care workers, over-50s and Britons with heart or kidney disease would be the first in line to get a Covid-19 vaccine.