Coronavirus vaccine could work better as a nasal spray than an injection
A coronavirus vaccine could be more effective at killing the virus as a nasal spray or inhaler, experts have said.
Researchers at Oxford University and Imperial College London, who are leading the UK’s race to find a vaccine, now believe getting the vaccine directly into the lungs will help fight the respiratory infection.
World-leading teams at both universities are testing their potential vaccines by injecting thousands of patients.
But the lead scientists are now looking at how their vaccines can be given through inhalers or a nasal spray, similar to how the flu jab is administered in children.
Professor Robin Shattock, who is leading the Imperial College London trial, told the House of Commons Science and Technology Committee: ‘At the moment most of the vaccines are being delivered by conventional intramuscular injection.
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‘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 University] and myself are already in discussion as to how me might be able to move that as a second wave of clinical study.’
Professor Sarah Gilbert, who is leading the Oxford Unversity trial, 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 [nasal spray] or aerosol delivery [inhaler].
‘This takes the vaccine itself right down into the lungs where it can access the same tissue that would be reached by the virus infection.’
Prof Gilbert also warned that current low transmission rates in the UK means there is ‘little chance’ that their trials will prove the effectiveness of a coronavirus vaccine.
She said that when Covid-19 transmission was high, lockdown was imposed to bring the rate down.
Rates have since dropped, but a sufficient number of volunteers have to be exposed to the virus to see whether a vaccine protects them or not.
However, if their chances of being in contact with an infected person are low, it will take a long time to demonstrate the efficacy of a vaccine candidate.
Prof Gilbert said: ‘Of course, what happened was that because it [transmission] actually increased much more rapidly than anybody thought was going to happen, we had the lockdown, which fortunately reduced transmission.
‘Not so fortunate for those of us trying to develop vaccines in the UK, because we now have essentially a very large safety immunogenicity study, running in the UK with little chance, frankly, of determining efficacy.’
She added that the researchers’ approach was to work with multiple different countries in different settings to give them the best chance of seeing efficacy in at least one of those countries.
The committee heard the Oxford team is already running a trial in Brazil because the numbers of transmissions are much higher than in the UK.
‘As soon as we get a signal of efficacy and can compare that to the level of immunity that we’re generating, that gives all vaccine developers really helpful information to let them know whether their vaccines are likely to work as well, and whether it will be one dose or two doses, and in older people and in younger people,’ she said.
‘So the first efficacy signal is going to be really important and as yet we don’t know which country will be generating that.’
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