Researchers to trial inhaled Covid-19 vaccines

Two of the UK’s Covid-19 vaccine candidates will be entered into a small clinical study to test how they work when inhaled into the lungs.

A team at the Imperial Network for Vaccine Research will compare the Covid-19 vaccine candidates, being developed by both Imperial College London and Oxford University, by delivering the them as airborne droplets, rather than an injection.

The trial, which is expected to recruit 30 volunteers, will assess the safety and efficacy of the vaccines when administered via inhalation. It’s hoped that this method will see the vaccine directly targeting the cells lining the airways, which is the typical point of infection for respiratory viruses. In doing so, the vaccine may induce a more effective immune response against the SARS-CoV-2 virus.

For each vaccine, researchers will assess three dose levels (low, medium and high dose) with three volunteers per group (18 in total), followed by an additional six in each group at the best dose (12 total).

If effective, the development of vaccines against Covid-19 could be potentially accelerated due to the possible additional delivery methods and targets.

Dr Chris Chiu, from the Department of Infectious Disease, and lead on the project, 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.”

As most people know, SARS-CoV-2 is a respiratory virus which “infects people through the cells lining the nose, throat and lungs,” Dr Chiu explained, but it is these surfaces within the body that “produce a different immune response to the rest of the body.” That’s why the team are exploring if targeting the airways directly can provide a more effective response compared to a traditional injected vaccine.

Dr Chiu will work alongside Imperial’s professor Robin Shattock and Oxford’s professor Sarah Gilbert on the project.

In addition to blood being analysed for the presence of neutralising antibodies (Immunoglobulin G, or IgG) and T cells, which fight the virus and protect against re-infection, the team will analyse nasal samples for the presence of specialised antibodies found in the nose and throat, called IgA, which would indicate a more specialised and localised immune response to the virus.

Professor Robin Shattock, from Imperial’s Department of Infectious Disease and 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. However, these trials are unlikely to tell us anything about the localised response in the nose, throat and airways – where the virus primarily attacks and invades cells.

“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, from the University of Oxford, 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 airborne virus. This is a small study which will provide some important information.”