The new coronavirus is a respiratory infection that infects us through our mouth, throat and nose. So it makes sense that a key way to stop the coronavirus from wreaking real havoc in us is to stop its advance at the front door.
That’s exactly why this week’s news that China had authorized the first-ever inhaled COVID-19 vaccine from CanSino Biologics – on India’s heels emergency clearance of Bharat Biotech’s COVID-19 Nasal Vaccine – was announced by the scientific community as a long-awaited breakthrough in vaccine development.
Investments in these technologies, health experts say, could protect against the constant evolution of the coronavirus, prevent more people from becoming infected and address some of the weaknesses of traditional vaccine injections.
“Nasal and oral vaccines are our best chance to block infections and transmission, contain the virus, reduce the number of diseases and help prevent #LongCovid,” tweeted physician-scientist Eric Topol, director of Scripps Research Translational Medicine, after announcing China’s inhalation vaccine this week. “They don’t get enough priority in the US”
With injected or “intramuscular” injections, including the groundbreaking mRNA-based vaccines developed by Pfizer and Moderna, the body relies on mounting immune responses by activating an arsenal of warriors such as T cells, B cells and other important parts of the immune system. This has proven to be extremely effective in preventing hospitalization and death from COVID-19.
Where it falls short is blocking the virus before it infects our bodies and adapting to new variants and sub-variants such as Omicron. That means the population remains vulnerable to an ever-mutating virus and breakthrough infections that could still land them in the hospital.
“During the first year of the pandemic, the meaningful evolution of the virus was slow, without any functional consequences, but since that time we have seen a succession of major variants of concern with increasing transmissibility and immune evasion, culminating in the Omicron genera,” wrote Akiko Iwasaki. from Topol and Yale University School of Medicine published in an overview of nasal vaccine technology in Science Immunology. “With that, there is a clear decrease in the capacity for vaccinations and booster shots to block infections and transmission.”
Nasal and inhaled vaccines, on the other hand, could enhance ‘mucosal immunity’, the susceptibility to invaders that can form in the body’s mucous membranes, including the gut and – more relevantly for COVID-19 – the respiratory tract. Respiratory vaccines build up slightly different versions of the body’s pathogen-fighting T cells and B cells, which can produce a more lasting memory of different types of pathogenic invaders.
These mucosal immune weapons can be more agile and versatile than other types, quicker to identify what should be allowed into the body in the first place and which nefarious microbes should be blocked. This may allow them to eradicate the virus at an earlier stage in the infection process. Like the injected vaccines, they can also trigger a downstream immune response in the body, meaning defenses can be built in both our airways and in our blood.
This is why scientists have long been trying to develop nasal or inhalation vaccines for flu – another seasonal, dynamic and endemic virus. However, those efforts have encountered a number of challenges, including the possibility of some serious side effects of ingredients called “adjuvants” which are often used to increase the effectiveness of vaccines. In clinical trials, the new Chinese and Indian COVID-19 vaccines were not associated with serious side effects.
Now scientists like Topol are advocating a new “Operation Warp Speed,” aimed at a long-term focus on these types of vaccines that prevent infection and transmission at an earlier stage.
It is still unclear whether the new vaccines from India and China can meet the evolving challenge of the coronavirus. But their milestone efforts, just like the once rejected science of mRNA vaccinescould certainly be a springboard for the future.