A COVID-19 vaccine candidate which can be administered through the nose showed a reduction in both the impact of the disease and transmission of the virus in pre-clinical animal trials, scientists say.
Researchers at Lancaster University in the UK immunised hamsters with two doses of the intranasal vaccine.
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They found the animals showed complete protection from lung infection, inflammation and lesions following exposure to the SARS-CoV-2 virus.
The two doses of the vaccine were found to significantly reduce the virus "shedding" from the nose and lungs of the hamsters -- suggesting the preventive has the potential to control infection at the site of inoculation, the researchers said.
This should prevent both clinical disease and virus transmission, to halt the spread of the COVID-19 pandemic, they said.
"Our studies demonstrate that induction of a local immune response at the point of entry of SARS-CoV-2 has the potential to not only limit clinical disease, but also -- and perhaps even more importantly -- virus transmission from infected to uninfected individuals," said Muhammad Munir, who led the study at Lancaster University.
The team, including researchers from Texas Biomedical Research Institute, US, noted that while injectable vaccines are offering significant reduction in hospitalisation and death, there is currently no registered intranasal vaccine against COVID-19.
The vaccine is based on a common poultry virus called the Newcastle Disease Virus (NDV), which can reproduce in humans but is harmless.
The scientists engineered NDV to produce the spike proteins of the SARS-CoV-2 virus which causes COVID-19, tricking the body into mounting an immune response against SARS-CoV-2.
The vaccine induced neutralising antibodies in animals against several novel variants of SARS-CoV-2, raising the possibility of broad protection in vaccinated individuals.
"After we administered the vaccine into the noses of hamsters and then infected them with SARS-CoV-2, we found almost no virus replication in the lungs and nasal wash of these animals," Munir said.
"In contrast, animals given normal NDV showed easily detectable SARS-CoV-2 virus replication in their lungs and nasal washes," he said.
The researchers noted that the results are a step towards developing a vaccine for COVID-19 which has the potential to increase the accessibility of a vaccine around the world.
Our study showed that this intranasal vaccine was safe and effective, providing the hamsters protection against SARS-CoV-2," said Professor Luis Martinez-Sobrido from Texas Biomedical Research Institute.
A vaccine nasal spray offers several advantages over conventional approaches including non-invasive administration, the induction of local immunity as well as being an alternative for people afraid of needles or with other medical conditions, the researchers said.
There is currently an intranasal influenza vaccine registered for human use so administering a vaccine in this way has already been proven to be effective, they said.
"We are excited by the scalability of this nasal vaccine which we hope will contribute to reducing vaccine inequity, allowing equal access to vaccination globally," said Lucy Jackson-Jones, a lecturer at Lancaster University,
"Nasal delivery is also a more appealing delivery route for use in children," she added.