Over the last few weeks, COVID-19 cases have surged in Asia, particularly in Hong Kong, Singapore, and Thailand. India has recorded 257 COVID-19 cases as of Monday, May 19, as per the Union Health Ministry. The health authorities are vigilant, especially with the JN.1 variant, a sublineage of Omicron, spreading globally. Vaccination played a crucial role in preventing the virus during the pandemic. Now, researchers have discovered a promising alternative to traditional COVID-19 shots, one that may be safer, more effective, and better at stopping the virus where it first enters the body: the nose.
How are nasal vaccines different from traditional ones
A new study by the researchers from Yale University found that nasal vaccine boosters could offer safer and more targeted protection against respiratory diseases such as COVID-19, without the need for traditional immune-boosting additives. The findings are published in the journal Nature Immunology.
Most vaccines and boosters are administered as injections directly into the muscle tissue, usually in the upper arm. But for respiratory diseases like COVID-19, protection right where the virus enters, the respiratory tract, could be crucial.
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The researchers found that nasal vaccine boosters can trigger strong immune defenses in the respiratory tract, even without the help of immune-boosting ingredients known as adjuvants.
“Our study shows how a simple viral protein antigen can boost respiratory tract immune responses against viruses,” said Akiko Iwasaki, Sterling Professor of Immunobiology at Yale School of Medicine (YSM) and senior author of the study. “These data imply that viral proteins in nasal spray may be used as a safe way to promote antiviral immunity at the site of viral entry.”
Mechanism of nasal vaccines
To understand the mechanism of the nasal vaccines, the researchers first injected mice with a traditional mRNA COVID-19 shot, directly into the muscle. Later, they gave the mice a booster vaccine through the nose. The researchers wanted to see the effects of vaccine boosters that don’t contain special ingredients known as adjuvants. This ingredient is used in some vaccines, to help stimulate a stronger, longer-lasting immune response. However, they can also have adverse effects, like inflammation and swelling of facial nerves.
“We call this vaccine strategy ‘prime and spike’, which is where the mice were intramuscularly primed with mRNA vaccines followed by a nasal boosting with unadjuvanted spike protein,” Dong-il Kwon, a postdoctoral fellow in Yale’s Department of Immunobiology, said in a statement.
The ‘prime and spike’ vaccine approach jumpstarts the immune response in the respiratory system, the first part of the body infected by COVID-19. ‘Prime’ refers to the process of administering a traditional intramuscular vaccine shot, while ‘spike’ refers to a follow-up vaccination delivered to the nose, usually in the form of a spray containing coronavirus-derived spike proteins.
The scientists found that only the nasal booster triggered a strong local immune response. Other boosters, including intramuscular injection, didn’t produce much IgA or activate immune cells in the lungs of the mice. When the researchers gave the mice a second nasal booster, their IgA levels increased even more in both the lungs and nasal passages.
“These findings help explain why nasal boosters do not require adjuvants to induce robust mucosal immunity at the respiratory mucosa and can be used to design safe and effective vaccines against respiratory virus pathogens,” Kwon added.
Regular COVID-19 shots don’t create much IgA in the nose and lungs. This is why people can still get infected or pass it on, even if they’re vaccinated. However, this study found that nasal boosters can trigger strong, long-lasting immune protection where respiratory diseases like COVID-19 first attack.
“Understanding how this safe and simple nasal booster promotes protective mucosal immunity will make it easier to develop this approach for human use in the near future,” Iwasaki said.
How are nasal vaccines different from traditional ones
A new study by the researchers from Yale University found that nasal vaccine boosters could offer safer and more targeted protection against respiratory diseases such as COVID-19, without the need for traditional immune-boosting additives. The findings are published in the journal Nature Immunology.
Most vaccines and boosters are administered as injections directly into the muscle tissue, usually in the upper arm. But for respiratory diseases like COVID-19, protection right where the virus enters, the respiratory tract, could be crucial.
Video
The researchers found that nasal vaccine boosters can trigger strong immune defenses in the respiratory tract, even without the help of immune-boosting ingredients known as adjuvants.
“Our study shows how a simple viral protein antigen can boost respiratory tract immune responses against viruses,” said Akiko Iwasaki, Sterling Professor of Immunobiology at Yale School of Medicine (YSM) and senior author of the study. “These data imply that viral proteins in nasal spray may be used as a safe way to promote antiviral immunity at the site of viral entry.”
Mechanism of nasal vaccines
To understand the mechanism of the nasal vaccines, the researchers first injected mice with a traditional mRNA COVID-19 shot, directly into the muscle. Later, they gave the mice a booster vaccine through the nose. The researchers wanted to see the effects of vaccine boosters that don’t contain special ingredients known as adjuvants. This ingredient is used in some vaccines, to help stimulate a stronger, longer-lasting immune response. However, they can also have adverse effects, like inflammation and swelling of facial nerves.
“We call this vaccine strategy ‘prime and spike’, which is where the mice were intramuscularly primed with mRNA vaccines followed by a nasal boosting with unadjuvanted spike protein,” Dong-il Kwon, a postdoctoral fellow in Yale’s Department of Immunobiology, said in a statement.
The ‘prime and spike’ vaccine approach jumpstarts the immune response in the respiratory system, the first part of the body infected by COVID-19. ‘Prime’ refers to the process of administering a traditional intramuscular vaccine shot, while ‘spike’ refers to a follow-up vaccination delivered to the nose, usually in the form of a spray containing coronavirus-derived spike proteins.
The scientists found that only the nasal booster triggered a strong local immune response. Other boosters, including intramuscular injection, didn’t produce much IgA or activate immune cells in the lungs of the mice. When the researchers gave the mice a second nasal booster, their IgA levels increased even more in both the lungs and nasal passages.
“These findings help explain why nasal boosters do not require adjuvants to induce robust mucosal immunity at the respiratory mucosa and can be used to design safe and effective vaccines against respiratory virus pathogens,” Kwon added.
Regular COVID-19 shots don’t create much IgA in the nose and lungs. This is why people can still get infected or pass it on, even if they’re vaccinated. However, this study found that nasal boosters can trigger strong, long-lasting immune protection where respiratory diseases like COVID-19 first attack.
“Understanding how this safe and simple nasal booster promotes protective mucosal immunity will make it easier to develop this approach for human use in the near future,” Iwasaki said.
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