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Trial will assess safety of potential vaccines when inhaled

Professor Robin Shattock, Imperial College London

Professor Robin Shattock, Imperial College London. Credit: Imperial College London/Thomas Angus

UKRI and National Institute for Health Research (NIHR)-funded researchers at Imperial College London will conduct trials to assess the safety and effectiveness of two potential coronavirus vaccines when inhaled into the lungs.

Clinical study

Researchers at Imperial College London funded through the COVID-19 rapid response call are set to begin trials with two of the UK’s potential coronavirus vaccines.

The clinical team will compare the COVID-19 vaccine candidates being developed by Imperial College London and Oxford University. The vaccines will be inhaled by human volunteers through the mouth, and then delivered directly to their respiratory tract.

Watch the video of Imperial College London’s vaccine:

Watch the video of the Oxford University vaccine:

The study aims to assess the safety and efficacy of administering the vaccines as airborne droplets inhaled by a volunteer, rather than an injection into muscle.

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 the SARS-CoV-2 virus.

This could accelerate the development of effective vaccines against COVID-19 by exploring additional delivery methods and targets.

Targeting airways directly

Dr Chris Chiu, from Imperial College London’s Department of Infectious Disease, said:

We have evidence that delivering influenza vaccines via a nasal spray can protect people against flu as well as help to reduce the 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 an effective immune response.

The current pandemic is caused by a respiratory virus which primarily infects people through the cells lining the nose, throat and lungs.

These surfaces are specialised and produce a different immune response to the rest of the body, so it is critical we explore whether targeting the airways directly can provide an effective response compared to a vaccine injected into muscle.

Vaccine delivery

Currently, clinical trials are being carried out to assess the safety and efficacy of multiple COVID-19 vaccines delivered by intramuscular injection: these include Oxford’s ChAdOx1 nCoV-19, as well as Imperial’s saRNA vaccine platform.

But scientists are keen to explore the potential for vaccines to be delivered to the respiratory tract. Here they could induce a localised, and potentially more specialised, immune response.

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 – similar to how inhaled asthma medications are delivered.

Volunteers will receive aerosolised vaccines through a nebuliser, which will deliver the vaccine as airborne droplets through a mouthpiece.

With direct vaccine administration to the respiratory tract, based on previous studies, it could be possible that lower doses will be required to induce protective responses, compared to injections.

Localised immune response

Professor Robin Shattock, research lead on the Imperial vaccine, said:

A number of groups around the world are currently working on clinical trials for COVID-19 vaccines, and these will tell us whether these candidates can produce a systemic immune response against the virus.

It may well be that one group has the right vaccine but the wrong delivery method, and only trials such as this will be able to tell us that.

We look forward to assessing different delivery methods and pushing forward the global scientific effort against this virus.

Professor Sarah Gilbert research lead on the University of Oxford vaccine said:

We have already shown that ChAdOx1 nCoV-19 (AZD1222) is safe and induces strong immune responses after intramuscular injection.

Delivering the vaccine to the respiratory tract instead may be a good approach to inducing immune responses in the best place to enable a rapid response after exposure to an airborne virus.

Professor Fiona Watt, Executive Chair of the Medical Research Council, said:

This study will tell us whether the two front-runner 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. We eagerly await the results of the study.

The study is recruiting healthy volunteers aged 18 to 55 for trials at a London facility. Volunteers will not be deliberately exposed to live or inactivated SARS-CoV-2 virus in these studies.

Last updated: 28 October 2020

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