Inactivated Vaccines
Inactivated vaccines, also known as whole-killed vaccines, use whole viruses that are dead. Although the virus cannot replicate, the body will still regard it as harmful and launch an antigen-specific response.7
Inactivated vaccines are used to prevent the following diseases:7
Subunit Vaccines
Subunit vaccines use only a piece of the germ or a bit of protein to spark an immune response. Because they don’t use the whole virus or bacterium, side effects aren’t as common as with live vaccines. With that said, multiple doses are typically needed for the vaccine to be effective.8
These also include conjugate vaccines in which the antigenic fragment is attached to a sugar molecule called a polysaccharide.
Diseases prevented by subunit vaccines include:7
Toxoid Vaccines
Sometimes it’s not the bacterium or virus you need protection against but rather a toxin that the pathogen produces when it is inside the body.
Toxoid vaccines use a weakened version of the toxin—called a toxoid—to help the body learn to recognize and fight off these substances before they cause harm.
Toxoid vaccines licensed for use include those that prevent:7
mRNA Vaccines
Newer mRNA vaccines involve a single strand molecule called messenger RNA (mRNA) that delivers genetic coding to cells. Within the coding are instructions on how to "build" a disease-specific antigen called a spike protein.
The mRNA is encased in a fatty lipid shell. Once the coding is delivered, the mRNA is destroyed by the cell.
There are four mRNA vaccines approved for use in 2024 to fight COVID-19:9
Before COVID-19, there were no mRNA vaccines licensed for use in humans.
Vaccine Safety
Despite claims and
myths to the contrary, vaccines work and, with few exceptions, are extremely safe. Throughout the development process, there are multiple tests vaccines must pass before they ever make it to your local pharmacy or healthcare provider's office.
Prior to being licensed by the FDA, manufacturers undergo stringently monitored
phases of clinical research to ascertain whether their vaccine candidate is effective and safe. This typically takes years and involves no less than 15,000 trial participants.10
After the vaccine is licensed, the research is reviewed by the
Advisory Committee on Immunization Practices (ACIP)—a panel of public health and medical experts coordinated by the Centers for Disease Control and Prevention (CDC)—to determine whether it is appropriate to recommend the vaccine and to which groups.10
Even after the vaccine is approved, it will continue to be monitored for safety and efficacy, allowing ACIP to adjust its recommendations as needed. There are three reporting systems used to track
adverse vaccine reactions and channel the report to ACIP:
- Vaccine Adverse Event Reporting System (VAERS)
- Vaccine Safety Datalink (VSD)
- Clinical Immunization Safety Assessment (CISA) Network
What Benefits Due Vaccinations Provide
By getting vaccinated, you can protect yourself and also avoid spreading preventable diseases to other people in your community. Some people cannot get certain vaccines because they are too young, elderly, have a weakened immune system, or have other serious health conditions.11
The more people within a community who are vaccinated against an
infectious disease, the fewer who are susceptible to the disease and likely to spread it. When enough vaccinations are given, the community as a whole can be protected against the disease, even those who have not been infected. This is referred to as
herd immunity.
The "tipping point" varies from one infection to the next but, generally speaking, a substantial proportion of the population must be vaccinated in order for herd immunity to develop.12
Herd Immunity with COVID-19
With COVID-19, studies determined herd immunity would require 75% to 85% of the population to be vaccinated, and the more the intensity of an infection, the more the population needs to be vaccinated.13
Herd immunity is what led public health officials to eradicate diseases like smallpox that used to kill millions. Even so, herd immunity is not a fixed condition. If
vaccine recommendations are not adhered to, a disease can re-emerge and spread throughout the population yet again.
Such has been seen with measles, a disease declared eliminated in the United States in 2000 but one that is staging a comeback due to declines in vaccination rates among children.14
Contributing to the declines in herd immunity are unfounded claims of harms from
anti-vaccination proponents who have long asserted that vaccines are not only ineffective (or created by corporate profiteers) but may also
cause conditions like autism, despite science confirming it is not true.
Considerations
The bulk of clinical evidence shows that the benefits of vaccination far outweigh any potential risks and that almost everyone should get the recommended vaccines at the recommended times.315
However, it is important to advise your healthcare provider if you are pregnant, are immunocompromised, or have had an adverse reaction to a vaccine in the past. In some cases, a vaccine may still be given, but in others, the vaccine may need to be substituted or avoided.
Summary
The point of getting vaccinated is to protect you and the people in your community from certain diseases. Vaccines help the body learn how to defend itself from disease without the dangers of a full-blown infection. Different types of vaccines work in different ways with the same goal of triggering an immune response. Vaccines work and are safe for almost everyone.
Vaccines serve the purpose of protecting you from diseases. Learn how your immune system reacts to vaccines to provide protection.
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