Vaccines are the most effective agents to control infections. In addition to the pathogen antigens, vaccines contain adjuvants that are used to enhance protective immune responses. However, the molecular mechanism of action of most adjuvants is ill-known. ~ Italian medical biologist Maria Vono et al
Vaccines put weak and dead viruses into the system, to be carted off and dissected. But there are only so many anti-bug bureaucrats.
More than 1 or 2 strains of a virus in a vaccine overloads the local lymph nodes that serve as police stations. This problem can be ameliorated by injecting different strains into different parts of the body, so different lymph nodes look at different suspects.
Any 1 of 4 strains of virus can cause dengue fever. Injecting the 4 strains in a single vaccine isn’t effective. One lymph node can only do so much at one time.
Instead injecting individual strains into different areas of the body eliminates local lymph node competition in figuring which strain to watch for, and is effective vaccination; though that too takes time: a few days for T cells from local nodes to circulate through the body, spreading the proverbial word.
Vaccines have limits. It has long been known that getting a flu shot one year can make you more susceptible the next year, as T cells are looking for last year’s model. But the rapid turnover in viral cells means rapid adaptation to changing conditions. As to pathogens, what doesn’t kill you makes you stronger.
The human immune system uses inflammation as a healing response: to focus forces to counter pathogens. But too much inflammation can be harmful. So immune cells signal to limit inflammation. To do so, they need a microbial assist.
Exposure to pathogens can strengthen child immune systems. When children are deprived of a healthy microbiome their immune systems get a poor education.
Untutored immune cells can unleash a tumult of inflammation. Instead of selectively killing off invaders, they damage their host.
The efficaciousness of vaccines rests upon their quality and administration protocol. There are many variables that determine whether a vaccine is worthwhile.
But there is one certainty. The pharmaceutical companies that manufacture vaccines are in the business of pushing their products. Profit only comes from volume sales.
Product quality is by no means assured. Testing can be cursory, or even manipulative, so to present positive results. Government oversight is scant. That makes the safety of vaccines something of a shot in the dark.