July 23, 2024

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Will Frequent irritation by booster of COVID-19 vaccine cause immune failure?

Will Frequent irritation by booster of COVID-19 vaccine cause immune failure?


Will Frequent irritation by booster of COVID-19 vaccine cause immune failure?  While COVID-19 Vaccines Save Millions of Lives, Not Enough to Prevent Breakthrough Infections. 

While COVID-19 boosters are being approved for vulnerable groups in the U.S., many are wondering what the end point will be.


Currently, the mRNA vaccine used in the United States has had great success in preventing hospitalizations and deaths from COVID-19. Federal funds recently reported that in the U.S. alone, vaccines have prevented more than 2 million deaths and more than 17 million from hospitalization.


However, vaccines do not provide long-term protective immunity against breakthrough infections — cases of COVID-19 infection that have occurred in fully vaccinated populations. Because of this, the CDC recently approved a second booster shot for people age 50 and older and the immunocompromised. Other countries, including Israel, the UK and South Korea, have also approved a second booster shot.


Will Frequent irritation by booster of COVID-19 vaccine cause immune failure?


However, a second booster dose also proved unable to provide lasting protection against breakthrough infections. Therefore, it is necessary to improve existing vaccines to extend the duration of protection, thereby helping to end the epidemic.

As immunologists study the immune response to infection and other threats, we also need to better understand how vaccine boosters induce the immune system to fight COVID-19.



Antibody is crucial to activate long-term immunity


Why do mRNA vaccines successfully prevent various symptoms of COVID-19, but not breakthrough infections? This is difficult to explain medically. Understanding this concept is critical to stopping new infections and controlling outbreaks.

What is unique about COVID-19 infection is that most infected people experience mild to moderate symptoms, while a small percentage of people develop severe infection symptoms that can lead to hospitalization and death.

Understanding how our immune systems work during mild and severe illness is also important for developing more targeted vaccines.

When people are first exposed to the SARS-CoV-2 virus that causes COVID-19, or the COVID-19 vaccine, the immune system activates two key immune cells, B cells and T cells. B cells produce Y-shaped protein molecules, or antibodies, that bind to the spike protein that protrudes from the virus’s surface, preventing the virus from entering the cell and preventing infection.

If enough antibodies are not produced, the virus escapes and infects host cells. When this happens, the immune system activates so-called killer T cells. These cells can recognize virus-infected cells immediately after infection and destroy them, preventing the virus from replicating and causing a wider infection.

As a result, there is growing evidence that antibodies may help prevent breakthrough infections, while killer T cells can prevent severe disease.



Why should people need to receive booster shot of COVID-19 vaccine?

B cells and T cells are unique in that they are transformed into memory cells after an initial immune response. Unlike antibodies, memory cells can exist in the body for decades and can respond quickly when confronted with the same infectious agent. It is because of such memory cells that some vaccines against diseases such as smallpox can protect us for decades.

But for vaccines to prevent things like hepatitis, multiple doses of the vaccine are necessary to boost the immune response. Because the dose of the first or second shot is not sufficient to activate powerful antibodies or maintain memory B- and T-cell responses.

An enhanced or amplified immune response helps increase the number of B cells and T cells that respond to infectious agents. Boosting immunity also triggers memory responses that provide long-term immunity and prevent reinfection.



 Does the 2nd booster of COVID-19 vaccine really a need?

While the third shot (or first booster shot) of the COVID-19 vaccine is very effective at preventing severe illness, it lasts less than four to six months for preventing infection.

The protection waned even after the third shot, which led the CDC to approve a fourth shot (the second booster) for the immunocompromised and people 50 and older.

However, a recent preliminary study in Israel, which has not yet been peer-reviewed, showed that the second booster dose did not further boost the immune response, but only restored the immune response that had waned during the previous third dose. In addition, the second booster dose provided little additional protection against COVID-19 compared to the previous three-dose vaccine.

So, while the second booster dose did extend months of immune protection for the most vulnerable, there is much doubt about what a fourth dose would mean for the general population.



Will Frequent irritation by booster of COVID-19 vaccine cause immune failure?


In addition to the inability of current COVID-19 vaccines to provide long-term immunity, some researchers believe that frequent or sustained exposure to foreign molecules found in infectious pathogens can lead to immune “exhaustion.”

This phenomenon has been widely reported in HIV infection and cancer. In this case, because the T cells keep “seeing” foreign molecules, they may be “exhausted” and unable to clear cancer or HIV from the body.

Evidence suggests that in critically ill patients with COVID-19, killer T cells may exhibit immune exhaustion and thus fail to mount a robust immune response. Whether repeated COVID-19 vaccine boosters lead to similar T-cell exhaustion requires further study.


The role of adjuvants in enhancing vaccine-induced immunity


Another reason for the failure of mRNA vaccines to induce sustained antibody and memory responses may be related to adjuvant components. Traditional vaccines such as diphtheria and tetanus use adjuvants to boost immune responses, compounds that activate innate immunity made up of macrophages. These are specialized cells that help T cells and B cells to induce stronger antibody responses.

Since mRNA-based vaccines are a relatively new class of vaccines, they do not contain traditional adjuvant components. mRNA vaccines currently used in the United States rely on lipid nanoparticles to deliver mRNA from fat globules. These lipid molecules can act as adjuvants, but the exact effect of these molecules on long-term immune responses remains to be seen. Whether the current COVID-19 vaccine’s inability to trigger a long-lasting potent antibody response is related to the adjuvant in the existing preparations remains to be explored.

While vaccines are highly effective in preventing severe disease, the next phase of vaccine development will need to focus on triggering an antibody response that lasts at least a year, making it possible for a COVID-19 vaccine to become an annual injection.




Will Frequent irritation by booster of COVID-19 vaccine cause immune failure?

(source:internet, reference only)

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