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How Are Vaccines Tested? | Vaccine Testing & Monitoring Services

Vaccines protect the population from outbreaks of diseases. They teach immune systems how to create antibodies, combatting a disease and often providing lifelong protection.

Before they can be distributed to the public, vaccines must be tested. Vaccines are tested multiple times in a lab, sometimes with animal testing, and then tested on humans in various clinical trials

Vaccine testing and development involves huge teams of scientists. Even when vaccines are fast-tracked, there’s a keen focus on quality control. In this article, we follow the journey of vaccine testing; asking how vaccines are tested and monitored, which ingredients vaccines contain, which development phases are involved, and who is responsible for approving vaccines.

Vaccine Testing and Monitoring

Due to the fact they are one of the only medical treatments administered to healthy people (including children), the testing and monitoring standard for vaccines is typically higher than the majority of other medicines. 

There is a lower level of acceptable risk compared to other treatments, such as medicines for life-threatening diseases. For this reason, it can take many years for vaccines to progress through all the required stages of testing. 

Phase 1 of human testing will involve a small cohort of adult participants, rarely more than 100 people. This phase ensures that the vaccine does not pose any significant safety concerns in humans. Phase 1 is also used to calculate the most effective dose of the vaccine.

Phase 2 will involve a larger group, several hundred people or more. Participants may be chosen from the target population (that is, the demographic that researchers think will benefit the most from the vaccine.) Scientists will check that the vaccine is working consistently and examine the immune response that it creates. Any potential side effects will also be noted.

Phase 3 typically involves a cohort of several thousand people, and clinical trials will focus on assessing both the safety and efficacy of the vaccine in humans. This entails determining whether a vaccine is enabling sufficient protection to prevent diseases, a reduction of the number of disease cases, or a reduction in harm to the individual. A group of over 3,000 participants may be required to assess the safety of a vaccine in a clinical trial before it is awarded a license. Phase 3 is also another chance to identify and report side effects.

Vaccine Ingredients

It is normal for some people to have concerns about vaccine injections and the safety of the ingredients used.
Vaccines contain an antigen, which is part of a germ (virus or bacteria.) Because the antigen is already dead or disabled before it is used in the vaccine, it won’t make the person given the vaccine sick. Antigens produce an immune response that protects the body from attacks when exposed to a disease.

Aside from an antigen, vaccines contain ingredients for safety and efficacy, such as additives, preservatives, adjuvants, and trace amounts of ingredients used in the production process (which may include yeast or egg protein.)

Some parents may have concerns about exposure to the antigens in vaccines. It should be noted that modern vaccines contain fewer antigens and that children’s bodies can usually handle multiple antigens or vaccinations at the same time.

Vaccine Development

Before the human testing stage which we covered earlier in this article, research and development will take place. This often begins with the exploration of a vaccine idea, which can involve the review of previous work done in the same area.

After the basis of an idea has been explored, it can be developed further – this will typically be a new idea for a vaccine, or an existing idea that has been modified in some way. 

Laboratory work can then start, with the vaccine being tested on cells (in vitro testing) followed by tests on animals, usually mice (in vivo testing.) A series of stringent safety tests will then be carried out. Researchers will need to show that the vaccine is able to cause an immune response in animals before the next stage can begin.

Development and monitoring will continue even after the vaccine has gone through the human testing phases and been approved, licensed, and distributed. 

Vaccine Approval

Agencies including the FDA and CDC will continue to monitor the safety of vaccines after it has begun to be administered, using systems such as the Vaccine Adverse Event Reporting System (VAERS), Vaccine Safety Datalink (VSD), and Clinical Immunization Safety Assessment (CISA) Project.

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