What Is the Difference Between Weakened and Dead Vaccines?

Vaccines are created with a common purpose: to keep us safe while stopping the spread of deadly illnesses. But, not all vaccines are developed in the same way. Two of the main types of vaccines are weakened and dead vaccines. What exactly are weakened and dead vaccines? And what is the difference between the two?

Weakened Vaccines

Weakened or attenuated vaccines are vaccines that contain weakened derivatives of a disease-causing pathogen. A pathogen is a foreign body such as a virus or bacteria that elicits an immune response when introduced into the body. With weakened vaccines, a weakened part of the live pathogen is injected into an individual to stimulate an immune response. This pathogen is weakened, or attenuated, through culturing in a laboratory, making them safe to be administered to the majority of the community.

After someone is vaccinated with a weakened vaccine, the virus or bacteria grows and replicates inside the body. The person’s immune system comes to recognize this pathogen for what it is, a foreign intruder. As a result, the vaccinated person’s immune response is triggered and antibodies against the virus or bacteria are produced. When the vaccinated person comes into contact with this pathogen in the community, they’re protected. Because of the antibodies it produced against the weakened pathogen after vaccination, this person’s body already knows how to fight off the wild virus or bacteria.

Dead Vaccines

Dead vaccines, also known as inactivated vaccines, are vaccines containing dead or inactive forms of a pathogen. These vaccines are made up of pathogens which are completely killed in a lab before administration to the community. These vaccines are killed using heat, chemicals or radiation.

When someone is vaccinated with a dead vaccine, the dead pathogen releases a toxin. The immune system recognizes the toxin or the pathogen itself and produces antibodies against it. When the vaccinated person comes into contact with the real pathogen in the community, the body already has some antibodies ready to fight off the virus or bacteria.

The Difference Between Weakened and Dead Vaccines

Because weakened vaccines contain the live version of a pathogen, they cause a stronger immune response than those of dead vaccines. This means that one dose of a weakened vaccine is usually enough to provide lifetime protection against a disease or illness. Dead vaccines, on the other hand, stimulate a weaker immune response. This requires multiple doses and boosters of the dead vaccine to provide longer lasting protection.

Weakened vaccines also require more involved handling since they contain live bacteria or viruses. These pathogens are highly unstable. They often require refrigeration to remain weakened and to keep from mutating. Dead vaccines can be stored without refrigeration. They don’t run the risk of mutating during handling and they are quite stable.

Weakened vaccines cannot be administered as freely as dead vaccines can be. Because weakened vaccines contain live pathogens, individuals with damaged or weakened immune systems should consider taking these vaccines with caution. While these vaccines are tested and proven to be safe for the majority of the community before administration, immunocompromised individuals may not be able to take them. But, dead vaccines can usually be administered to anyone regardless of the state of their immune system.

Safety and Efficacy of Weakened and Dead Vaccines

Though it might seem dangerous to intentionally put a virus or bacteria into the body, the concept of weakened vaccines is proven to be safe for the majority of people. The pathogen is carefully weakened in a controlled environment, making it strong enough to elicit an immune response but weak enough to leave the vaccinated person unharmed.

The body’s response to weakened vaccines is very strong. Since weakened vaccines train the immune system to produce life-long antibodies against dangerous pathogens, a single dose is often sufficient to provide protection. Some common weakened vaccines that have helped to keep the majority of communities safe are the vaccines against: chicken pox, measles, mumps, rubella and yellow fever.

Dead vaccines are also proven to be safe for most in the community. The pathogens in dead vaccines are completely killed off, making them safe even for those with weakened immune systems. And as long as an individual does not have any allergies to an inactive ingredient in a dead vaccine, it is safe for administration.

Though the body’s response to dead vaccines isn’t as strong as it is to weakened vaccines, dead vaccines still give a good amount of protection. One will usually need to get booster shots or supplemental doses in order to prolong protection. However, as long as a regular vaccination schedule is followed, dead vaccines are effective in providing protection against illnesses. Some common dead vaccines currently being administered are: influenza, hepatitis A, cholera and pertussis.

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Ese Agboh is a student nurse who wants to specialize in pediatric nursing and wound care. In her free time, she enjoys reading and writing articles related to medicine and the pathophysiology of communicable diseases. Ese currently lives and studies on the east coast of the United States.