Understanding the Vaccine Development Process

With the current Covid-19 pandemic gripping the U.S. and the world, the race is on to quickly develop an effective vaccine to help prevent the spread of the virus. Until most of the world has been vaccinated, it will be extremely difficult to contain the spread of the virus. Understandably, many have the same question on their mind: When will a vaccine be ready?

What is a vaccine?

A vaccine is a medicine that helps your body build antibodies (proteins produced by the immune system in response to the presence of a foreign substance) to protect from certain diseases.^1,2  Once you receive a vaccination, your immune system thinks you have been previously exposed to the disease by imitating an infection. This helps your body build those antibodies that will help fight off future infections. It’s important to remember that vaccines are only for prevention purposes. Vaccines are not for treatment and this is why it is important to receive all childhood and adult vaccinations in a timely manner.  

How are vaccines developed?

It may take several years to develop a vaccine. The process requires a lot of time and resources to ensure safety and that it works for patients. The 5 main stages of vaccine development include: exploratory, pre-clinical, clinical development, approval, and pharmacovigilance stages. Stage development and typical length of time information as follows:

• Exploratory Stage (2-4 Years): As the first stage, this is where the laboratory research is done to find an antigen (molecules capable of stimulating an immune response to eventually help your body build antibodies) for the vaccine. Antigens can be made up of several substances including virus-like particles, weakened viruses or bacteria, weakened bacterial toxins or other substances that derived from pathogens.³
• Pre-Clinical Stage (1-2 years): In this stage, various tests are done in cells, tissues and animals. This determines the safety of the vaccine, ways to give the vaccine, appropriate doses for patients and how well it leads to an immune response (immunogenicity).³ All these tests are done to make sure it is actually safe to test the vaccine in humans and to verify it does not have the potential to cause serious harm to patients. Not every vaccine tested makes it to the clinical stage.
• Clinical Stage: Once a vaccine has been approved to move on to the Clinical stage, it is ready to be tested in humans. This stage can be broken down into 3 sub-phases: Phase I, Phase II and Phase III trials.
  1. Phase I (2 years): This usually involves testing the vaccine on 20-80 volunteers. The goal is to determine the safety, side effects, appropriate dosing, and immune response of the vaccine. The goal is to see if the vaccine works as expected (did the vaccine prevent the disease and did it lead to the production of antibodies).⁴
  2. Phase II (2-3 years) . If the results from the Phase I trial is positive, the vaccine will progress to Phase II. This phase involves a larger group (up to hundreds) of volunteers. Volunteers are randomly selected to receive either the experimental vaccine or a placebo (saline solution, a vaccine for another disease or some other substance).³ The goal is to continue to monitor the vaccines safety, doses for the vaccine, determine the schedule for giving the immunization (e.g giving a 2^nd dose 3 months after first dose) and through which method to deliver the vaccine (oral, subcutaneous, intramuscular, intradermal, and intranasal).⁴
  3. Phase III (5-10 years): This involves tens of thousands of people and volunteers are randomly assigned into experimental or placebo group like Phase II. Main goal is to assess the safety and efficacy of the vaccine in a much larger group of people especially in the population for which the vaccine is aimed for.⁴ This is because it is easier to find a rare side effect in a larger group of people than smaller a smaller population.³

• Approval and Licensure: When a vaccine has successfully completed Phase III trials, the sponsor of the vaccine follows a multi-step approval process.⁵ FDA licenses the vaccine only if it is safe and effective and the benefits of the vaccine outweighs the risks for patients.
• Phase IV or pharmacovigilance: Even after the vaccine comes out to the market, the manufacturer of the vaccine will continue to monitor the vaccines safety to detect any adverse events. FDA will also continue to observe the production of the vaccine to ensure that it is safe for the population.⁵

Where can I report any adverse events from a vaccine?

If you believe there is an association between a vaccination and an adverse event, you or anyone else may report that event and information to the Vaccine Adverse Event Reporting System (VAERS). This is a national safety surveillance program created by the CDC and FDA.⁵ With all the reported cases, the CDC will go in and look through these events and see if they are actually caused by the vaccination. Although it is also important to remember that not all adverse events reported to VAERS is caused by a vaccination, it is encouraged to report all side effects no matter how big or small.

References:

1. The Editors of Encyclopaedia Britannica. “Antibody.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 27 May 2020, britannica.com/science/antibody.
2. “Basics of Vaccines.” CDC, Centers for Disease Control and Prevention, 14 Mar. 2012, cdc.gov/vaccines/vpd/vpd-vac-basics.html.
3. “Vaccine Development, Testing, and Regulation.” History of Vaccines, The College of Physicians of Philadelphia, 2018, http://www.historyofvaccines.org/content/articles/vaccine-development-testing-and-regulation.
4. “The Complex Journey of a Vaccine.” IFPMA, International Federation of Pharmaceutical Manufacturers & Associations, July 2019, http://www.ifpma.org/wp-content/uploads/2019/07/IFPMA-ComplexJourney-2019_FINAL.pdf.
5. “Vaccine Testing and Approval Process.” CDC, Centers for Disease Control and Prevention, 1 May 2014, cdc.gov/vaccines/basics/test-approve.html.