Inhaled versions of two of the UK’s potential Covid-19 vaccines are being trialled in a new study.

The Imperial College London study will examine the safety and effectiveness of administering the vaccines as inhaled airborne droplets, similar to how inhaled asthma medications are taken.

Researchers will compare a vaccine being developed by Imperial College London, and the Oxford University and AstraZeneca vaccine, in the study.

The hope is that directly targeting the cells lining the airways – the typical point of infection for respiratory viruses – may induce a more effective immune response against Covid-19, Imperial College London said.

Dr Chris Chiu, lead researcher on the study, said there is already evidence that delivering flu vaccines via a nasal spray can protect against and reduce transmission of the disease.

‘We are keen to explore if this may also be the case for SARS-CoV-2 and whether delivering Covid-19 vaccines to the respiratory tract is safe and produces and effective immune response,’ he said.

He added that it was ‘critical’ to explore whether targeting the airways directly can provide an effective response, given that the current pandemic is caused by a respiratory virus that ‘primarily infects people through the cells lining the nose, throat and lungs’.

How the study works

Dr Chiu will work with Imperial’s Professor Robin Shattock and Oxford’s Professor Sarah Gilbert to assess the vaccines by delivering them to a small group of healthy volunteers as an aerosol.

Thirty people are expected to be recruited and for each vaccine, researchers will assess three dose levels – low, medium and high – with three volunteers per group (18 in total), followed by an additional six in each group at the best dose (12 in total).

Volunteers will receive aerosolised vaccines through a nebulizer, which will deliver the vaccine as airborne droplets through a mouthpiece. As well as having their blood and nasal samples analysed, volunteers will undergo bronchoscopy to obtain samples from deeper within the lungs and monitor the effects in the lower respiratory tract.

Researchers are currently recruiting for volunteers aged 18 to 55 and the trials will begin at a west London facility in the next few weeks. The participants will not be deliberately exposed to live or inactivated SARS-CoV-2 virus, Imperial College London said.

‘Frontrunner vaccines’

Professor Fiona Watt, executive chair of the Medical Research Council, part of UK Research and Innovation, said: ‘This study will tell us whether the two frontrunner vaccines in the UK for COVID-19 would be as effective if administered by inhalation rather than an injection.

‘It will be interesting to see whether an inhaled version of the vaccine might offer a more immediate form of protection and whether it would have advantages in terms of making a vaccine available to large numbers of people.’

Clinical trials are already being carried out to assess the safety and efficacy of numerous Covid-19 vaccines that are delivered by intramuscular injection. These trials include Oxford’s ChAdOx1 nCoV-19 vaccine, as well as Imperial’s saRNA vaccine platform.