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The Developing Process of a Coronavirus Vaccine

Pre-Clinical

In the Pre-Clinical stage, the vaccine is given to animals to identify potential safety concerns and test if it triggers an immune response.

Phase I

In Phase I trials, the vaccine is given to small groups of people (approximately 20 to 80) to test its safety and confirm that it stimulates the immune system.

Phase II

In Phase II trials, the vaccine is given to several hundred people, especially people of different ages, to test its effectiveness.

Phase III

In Phase III trials, the vaccine is given to several thousand people to confirm and expand on safety and effectiveness results from previous trials.

Limited Use

Some countries approve vaccines for emergency use before their results from Phase III trials. Under Limited Use, only certain groups of people will have access to the vaccine.

Approval

In this stage, regulators in each country review the results and decide to approve the vaccine or not. After a vaccine receives approval, it will be distributed across the country.

Pre-Clinical In the Pre-Clinical stage, the vaccine is given to animals to identify potential safety concerns and test if it triggers an immune response.

Phase I In Phase I trials, the vaccine is given to small groups of people (approximately 20 to 80) to test its safety and confirm that it stimulates the immune system.

Phase II In Phase II trials, the vaccine is given to several hundred people, especially people of different ages, to test its effectiveness.

Phase III In Phase III trials, the vaccine is given to several thousand people to confirm and expand on safety and effectiveness results from previous trials.

Limited Use Some countries approve vaccines for emergency use before their results from Phase III trials. Under Limited Use, only certain groups of people will have access to the vaccine.

Approval In this stage, regulators in each country review the results and decide to approve the vaccine or not. After a vaccine receives approval, it will be distributed across the country.

Other Stages During Development

Combined Phases

In order to accelerate the vaccine development process, some companies may decide to combine different stages of their trials. For example, a Phase I/II trial is a combination of Phase I and Phase II trials.

Paused

If investigators found adverse reactions among participants, they may decide to pause the trial. After a detailed investigation, the trials may resume or be abandoned.

Abandoned

If troubling symptoms were found due to injection of the vaccine, or if the vaccine failed to yield antibodies among certain groups of people, the vaccine may be abandoned due to safety concerns.

Combined Phases In order to accelerate the vaccine development process, some companies may decide to combine different stages of their trials. For example, a Phase I/II trial is a combination of Phase I and Phase II trials.

Paused If investigators found adverse reactions among participants, they may decide to pause the trial. After a detailed investigation, the trials may resume or be abandoned.

Abandoned If troubling symptoms were found due to injection of the vaccine, or if the vaccine failed to yield antibodies among certain groups of people, the vaccine may be abandoned due to safety concerns.