I am truly sorry as I am not sure I understand what you are saying.
It is my understanding that your goal is to get the world's population to the point where Corona strain Covid19 is no longer being actively transmitted. That those who might come into contact with an active case will not get infected and/or subsequently pass it on to others.
If my understanding of the goal is correct then I will say this is a very unrealistic goal for the following reasons.
Immunity is not that you are impervious to the infection, that you can not get infected or during the infected phase not be shedding the virus, it simply means one natural immunity cells are hopefully able to quickly respond. Age and health also greatly factor into the immune response and its entirely possible that a young healthy person who is simply stressed out about a final exam would even after getting a vaccine end up with a higher viral load, more virus shedding, and longer recovery time then if they were not stressed.
Types of Vaccines
The key to vaccines is injecting the antigens into the body without causing the person to get sick at the same time. Scientists have developed several ways of doing this, and each approach makes for a different type of vaccine.
Live Attenuated Vaccines: For these types of vaccines, a weaker, asymptomatic form of the virus or bacteria is introduced into the body. Because it is weakened, the pathogen will not spread and cause sickness, but the immune system will still learn to recognize its antigens and know to fight in the future.
- Advantages: Because these vaccines introduce actual live pathogens into the body, it is an excellent simulation for the immune system. So live attenuated vaccines can result in lifelong immunity with just one or two doses.
- Disadvantages: Because they contain living pathogens, live attenuated vaccines are not given to people with weakened immune systems, such as people undergoing chemotherapy or HIV treatment, as there is a risk the pathogen could get stronger and cause sickness. Additionally, these vaccines must be refrigerated at all times so the weakened pathogen doesn't die.
- Specific Vaccines:
- Measles
- Mumps
- Rubella (MMR combined vaccine)
- Varicella (chickenpox)
- Influenza (nasal spray)
- Rotavirus
Inactivated Vaccines: For these vaccines, the specific virus or bacteria is killed with heat or chemicals, and its dead cells are introduced into the body. Even though the pathogen is dead, the immune system can still learn from its antigens how to fight live versions of it in the future.
- Advantages: These vaccines can be freeze dried and easily stored because there is no risk of killing the pathogen as there is with live attenuated vaccines. They are also safer, without the risk of the virus or bacteria mutating back into its disease-causing form.
- Disadvantages: Because the virus or bacteria is dead, it's not as accurate a simulation of the real thing as a live attenuated virus. Therefore, it often takes several doses and "booster shots" to train the body to defend itself.
- Specific Vaccines:
- Polio (IPV)
- Hepatitis A
- Rabies
Subunit/conjugate Vaccines: For some diseases, scientists are able to isolate a specific protein or carbohydrate from the pathogen that, when injected into the body, can train the immune system to react without provoking sickness.
- Advantages: With these vaccines, the chance of an adverse reaction in the patient is much lower, because only a part or the original pathogen is injected into the body instead of the whole thing.
- Disadvantages: Identifying the best antigens in the pathogen for training the immune system and then separating them is not always possible. Only certain vaccines can be produced in this way.
- Specific Vaccines:
- Hepatitis B
- Influenza
- Haemophilus Influenzae Type B (Hib)
- Pertussis (part of DTaP combined immunization)
- Pneumococcal
- Human Papillomavirus (HPV)
- Meningococcal
Toxoid Vaccines: Some bacterial diseases damage the body by secreting harmful chemicals or toxins. For these bacteria, scientists are able to "deactivate" some of the toxins using a mixture of formaldehyde and water. These dead toxins are then safely injected into the body. The immune system learns well enough from the dead toxins to fight off living toxins, should they ever make an appearance.
Conjugate Vaccines: Some bacteria, like those of
Hib disease, possess an outer coating of sugar molecules that camouflage their antigens and fool young immune systems. To get around this problem, scientists can link an antigen from another recognizable pathogen to the sugary coating of the camouflaged bacteria. As a result, the body's immune system learns to recognize the sugary camouflage itself as harmful and immediately attacks it and its carrier if it enters the body.
- Specific Vaccines:
- Haemophilus Influenzae Type B (Hib)
DNA Vaccines: Still in experimental stages, DNA vaccines would dispense with all unnecessary parts of a bacterium or virus and instead contain just an injection of a few parts of the pathogen's DNA. These DNA strands would instruct the immune system to produce antigens for combating the pathogen all by itself. As a result, these vaccines would be very efficient immune system trainers. They are also cheap and easy to produce.
- Specific Vaccines: DNA vaccines for influenza and herpes are currently in human testing phases.
Recombinant Vector Vaccines: These experimental vaccines are similar to DNA vaccines in that they introduce DNA from a harmful pathogen into the body, triggering the immune system to produce antigens and train itself to identify and combat the disease. The difference is that these vaccines use an attenuated, or weakened, virus or bacterium as a ride, or vector, for the DNA. In essence, scientists are able to take a harmless pathogen, dress it in the DNA of a more dangerous disease, and train the body to recognize and fight both effectively.
- Specific Vaccines: Recombinant vector vaccines for HIV, rabies, and measles are currently being developed.
Things that so far have proven resilient to any attempt to derive a vaccine for like HIV and Herpes are because of how the virus interacts with the body bypassing the advances in training the natural immune response. Remember the vaccine doesn't prevent you from the initial point of infection, it simply speeds up the body's response to the infection, which is the same response that happens naturally to subsequent infections by the same pathogen.
As for eradication of diseases, only smallpox has been declared eradicated by vaccination. 13 others have been significantly reduced in a number of countries but are not yet eradicated, all 13 of are not known to exist in a carrier state and thus once they are eradicated in the human population they should be gone.
In fact, smallpox vaccine was first created due to a less severe zoonotic strain cowpox which allowed for further development on vaccine research.
Influenza (common cause of the seasonal flu) requires a yearly shot and its effectiveness varies year to year depending on the strains that are prevalent in your area and the forecasted strains included in the yearly vaccination (6 months from when the commit decides now which strains to include to when made available). Influenza, like Corona, has several carrier animal populations and is highly zoonotic combined with high mutational evolution allows it to escape the immunity that is induced by prior infections or vaccinations. Here are some more links if you wish to dive deeper into how this works.
The Evolution of seasonal influenza viruses,
Comparison of the mutation rates of human influenza A and B Viruses,
SARS-CoV-2 and influenza: a comparative overview and treatment implications.
The end result is Corona Virus which Covid19 is an offspring of has been around a long time, is highly mutable which creates a difficult obstacle to preventing and controlling by vaccination. Herd immunity was never about eradicating Covid19 but about reducing the severity of the infection in individuals and thus reducing long-term complications and death in the population. If the novel strain SARS-Cov-2 had been caught and not allowed to spread beyond Wuhan then it might have been eradicated as it would not have had a chance to infect animal carrier populations like the previous generation. But on a whole Corona will continue to infect animals and humans and produce new novel strains.
Human Coronavirus Types People around the world commonly get infected with human coronaviruses 229E, NL63, OC43, and HKU1. I will wager that list going forward will now include SARS-Cov-2 and 10 to 15% of the world's population will be infected by it on a semi-yearly basis and will not be able to tell the difference between it and Influenza. In a year or two as much as it frustrates me we will be back to people going to school and work sick and sharing their cold.
