Inhalable Covid vaccine shows promise in trials

Researchers have created an inhalable Covid-19 vaccine that allows for self-administration via an inhaler.

The vaccine is shelf stable at room temperature for up to three months and targets the lungs specifically and effectively.

Ke Cheng, the Randall B. Terry Jr. Distinguished Professor in Regenerative Medicine at NC State and a professor in the NC State/UNC-Chapel Hill Joint Department of Biomedical Engineering, along with colleagues from UNC-Chapel Hill and Duke University, led the development of the vaccine prototype from proof-of-concept to animal studies.

‘There are several challenges associated with vaccine delivery we wanted to address,’ Cheng explained. ‘First, taking the vaccine via intramuscular shot is less efficient at getting it into the pulmonary system, and so can limit its efficacy. Inhaled vaccines would increase their benefit against COVID-19.

‘Second, mRNA vaccines in their current formulation require cold storage and trained medical personnel to deliver them. A vaccine that is stable at room temperature and that could be self-administered would greatly reduce wait times for patients as well as stress on the medical profession during a pandemic. However, reformulating the delivery mechanism is necessary for it to work through inhalation.’

In order to deliver the vaccine directly to the lungs, the researchers used exosomes (Exo) secreted from lung spheroid cells (LSCs). Exosomes are nanosized vesicles that have recently been recognized as an excellent means of drug delivery.

The researchers found that the delivery mechanism for this vaccine – a lung-derived exosome called LSC-Exo – is more effective at evading the lung’s mucosal lining than the lipid-based nanoparticles currently in use, and can be used effectively with protein-based vaccines.

In rodent models, the vaccine protected the animals after two vaccine doses from infection with live SARS-CoV-2.

The researchers note that while the work is promising, there are still challenges associated with large-scale production and purification of the exosomes. LSCs, the cell type used for generating RBD-Exo, are currently in a Phase I clinical trial by the same researchers for treating patients with degenerative lung diseases.

‘An inhalable vaccine will confer both mucosal and systemic immunity, it’s more convenient to store and distribute, and could be self-administered on a large scale,’ Cheng added. ‘So while there are still challenges associated with scaling up production, we believe that this is a promising vaccine worthy of further research and development.’

Photo by Bob Williams