Scientists at McMaster University in Canada have developed an inhaled form of COVID-19 vaccine that can offer broad and long-lasting protection against SARS-CoV-2 variants of concern, a preclinical study has found.
The study, published recently in Cell, discusses the immune mechanisms and the benefits of delivering vaccines directly to the respiratory tract rather than by injection.
Inhaled vaccines are far more effective at inducing a protective immune response since they target the lungs and upper airways, where respiratory viruses first enter the body, claim researchers.
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Researchers conducted an animal model study to provide critical proof of concept that will enable Phase 1 clinical trials currently being conducted to evaluate inhaled aerosol vaccines in healthy adults who have already had two doses of COVID-19 mRNA vaccine.
The strategy was built upon a robust tuberculosis vaccine research programme established by Zhou Xing, a co-lead author of the study.
“What we have discovered from many years’ research is that the vaccine delivered into the lung induces all-around protective respiratory mucosal immunity, a property that the injected vaccine is lacking,” said Xing, professor at McMaster University.
The new vaccine, which targets parts of the virus, is effective against highly transmissible variants because it targets parts that are highly conserved among coronaviruses and do not mutate as quickly as a spike.
According to the researchers, all COVID-19 vaccines approved today target only the spike protein, which has shown remarkable mutating capabilities. SARS-CoV-2 enters and infects human cells using the spike protein.
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“This vaccine might also provide pre-emptive protection against a future pandemic, and that is really important because as we have seen during this pandemic — and as we saw in 2009 with the swine flu — even when we are able to rapidly make a vaccine for a pandemic virus, it’s already way too late,” said Miller.
In addition to neutralising antibodies and T cell immunity, the researchers discovered that the vaccine stimulated a form of immunity known as trained innate immunity.
They said this type of immunity provides very broad protection against many lung pathogens, besides SARS-CoV-2.
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Researchers said an inhaled vaccine is so effective at targeting the lungs and upper airways that it can deliver maximum protection without needles or pain. Researchers said the protection could be achieved with a fraction of the dose of current vaccines – as little as 1 per cent – meaning a single batch of vaccine could go 100 times farther.
“This pandemic has shown us that vaccine supply can be a huge challenge,” said associate professor Brian Lichty, who co-led the preclinical study.
“Demonstrating that this alternative delivery method can significantly extend vaccine supply could be a game changer, particularly in a pandemic setting,” Lichty added.
