Landmark Coronavirus Study to Trial Inhaled Imperial and Oxford COVID-19 Vaccines

A small clinical study will compare COVID-19 vaccine candidates being developed by both Imperial College London (London, UK) and the University of Oxford (Oxford, UK) by delivering the vaccines directly to the respiratory tract of human volunteers, via inhalation through the mouth.

Currently, clinical trials are being carried out to assess the safety and efficacy of multiple COVID-19 vaccines delivered by intramuscular injection. However, scientists are keen to explore the potential for vaccines to be delivered to the respiratory tract where they could induce a localized, and potentially more specialized, immune response. It is unclear how this compares to the systemic immune response induced by injected vaccines. Imperial researchers are now set to begin trials to assess the safety and effectiveness of two of the UK’s coronavirus vaccines in development, when inhaled into the lungs.


The study aims to assess the safety and efficacy of administering the vaccines as airborne droplets inhaled by volunteers, rather than an injection into muscle. The vaccines will be delivered to a small group of healthy volunteers as an aerosol, similar to how inhaled asthma medications are delivered. Volunteers will receive aerosolized vaccines through a nebulizer, which will deliver the vaccine as airborne droplets through a mouthpiece. With direct vaccine administration to the respiratory tract, based on previous studies, lower doses may be required than by intramuscular injections to induce protective responses. 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 potentially accelerate the development of effective vaccines against COVID-19 by exploring additional delivery methods and targets.

A total of 30 people are expected to be recruited to the trials. 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). In addition to blood and nasal sample analyses, volunteers will undergo bronchoscopy to obtain samples from deeper within the lungs and monitor the effects in the lower respiratory tract. In addition to blood being analyzed for the presence of neutralizing antibodies (Immunoglobulin G, or IgG) and T cells, which fight the virus and protect against re-infection, the team will analyze nasal samples for the presence of specialized antibodies found in the nose and throat, called IgA, which would indicate a more specialized and localized immune response to the virus.

“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,” said Dr. Chris Chiu, from the Department of Infectious Disease, who will lead the project.

“We have already shown that ChAdOx1 nCoV-19 (AZD1222) is safe and induces strong immune responses after intramuscular injection,” said Professor Sarah Gilbert, from the University of Oxford. “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.”

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Imperial College London
University of Oxford