Scientists from Monash University and the National University of Singapore have engineered a COVID-19 vaccine that, in pre-clinical models, has shown very long-lasting, protective immunity with a single-shot.
The scientific team say the new technology may potentially address the issue of waning COVID-19 vaccine immunity, and eliminate the need for repeated booster jabs, particularly for people aged 60 and over, medically vulnerable individuals and their caregivers.
“The results that we see in this study are very promising, and we are confident that the work performed in pre-clinical models is highly translatable to humans,” said Associate Professor Sylvie Alonso, Principal Investigator of this study.
“Indeed, a human equivalent of this immune cell subset exists, and our collaborator, Associate Professor Mireille Lahoud, at Monash University is developing this approach towards future human application.”
Upon a single shot immunisation of the team’s antibody construct, they monitored the immune responses in pre-clinical models over 21 months, and found no signs of declined immunity. In contrast, it was observed that the quality of the immune response (the neutralising antibody response, in particular), was associated with increased protection over time.
The study was published in Molecular Therapy, which is part of Cell Press.
“This study demonstrates the strength of our platform targeting specialised immune cells for vaccine improvement, and exemplifies the power of international research collaborations spanning basic discoveries to translational studies,” said Associate Professor Lahoud.
“There remain many diseases where effective vaccines have proven difficult to generate. Validation of this platform provides strong proof-of-concept for application to such challenges,” she said.
Current Messenger RNA (mRNA) COVID-19 vaccines have been reported to demonstrate peak effectiveness of 62% after three weeks, post-jab, before declining to 9% after nine months. Protection from booster doses has been reported to wane, dropping from 60% one month after the booster dose to 13% at nine months.
“Our teams in NUS Medicine and Monash University foresee that the exceptional durability of the immune responses induced by the Clec9A targeting technology, when used as a booster vaccine strategy, may address the shortcoming of current mRNA vaccines, chief of which is the rapid waning of immune responses,” Associate Professor Alonso, who is also co-Director of the Infectious Diseases Translational Research Programme at NUS Medicine said.
“We are now evaluating our vaccine candidate as a booster vaccine in mRNA-vaccinated pre-clinical models. We hope to demonstrate that this booster approach will induce long-term protective immunity, and avoid the need of multiple (annual) booster shots.
“Beyond COVID19, this versatile, rapidly-deployable vaccine platform shows promising potential to be part of the pandemic response against diseases caused by unknown pathogens in the future.”