Developing a vaccine: how long does it really take?

This is a guest blog by Manal Almaqaleh

A vaccine is a safe form of an antigen, which is injected into the bloodstream to provide artificial active immunity against a pathogen bearing the antigen. In other words, it is a type of medicine that trains the body’s immune system so that it can fight a disease it has not come into contact with before. Vaccines are designed to prevent disease, rather than treat a disease once you have caught it. In the UK babies are given vaccinations against a range od diseases including pertussis, diphtheria, meningitis and measles. As a result, the number of children who die from preventable infections is now very low.

At the beginning of an epidemic, mass vaccination can prevent the spread of the pathogen into the wider population. When vaccines are being deployed to prevent epidemics, they often to be changed regularly to remain effective. When a significant number of people in the population have been vaccinated, this gives protection to those who do not have immunity. This is known as herd immunity, as there is minimal opportunity for an outbreak to occur.


The effectiveness and life-saving nature of vaccines leads people to pose the same question whenever a public health crisis, such as Coronavirus or Ebola, hits the news cycle: “When will a vaccine be available?” The answer, which also considers which types of professionals are needed at each stage of development, is complicated.  According to the CDC, there are six stages of vaccine development: exploratory, pre-clinical, clinical development, regulatory review and approval, manufacturing, and quality control. And for this reason, it takes a while for a vaccine to be produced and ready to be injected into individuals.


Vaccine development is a long, complex process, often lasting 10-15 years and involving a combination of public and private involvement. The exploratory stage involves basic laboratory research and often lasts 2-4 years where scientists identify natural or synthetic antigens that might help prevent or treat a disease. The preclinical stage is where they use tissue-culture or cell-culture systems and animal testing to assess the safety of the candidate vaccine and its immunogenicity, or ability to provoke an immune response. Animal subjects may include mice and monkeys. These studies give researchers an idea of the cellular responses they might expect in humans. The clinical development stage is where a sponsor, usually a private company, submits an application for an Investigational New Drug (IND) to the Food and Drug Administration (FDA). This summarises findings to date and describes how the drug will be tested and created. An institution that will host the clinical trial holds a review board for approval of the application. The FDA has 30 days to approve the application. Once the proposal has been approved, the vaccine must pass three trial stages of human testing:


  • Phase I, administers the candidate vaccine to a small group (less than 100 people) with the goal of determining whether the candidate vaccine is safe and to learn more about the responses it provokes among test subjects.

  • Phase II, which includes hundreds of human test subjects, aims to deliver more information about safety, immunogenicity, immunization schedule and dose size.

  • Phase III, which can include thousands, or tens of thousands of tests subjects, continues to measure the safety (rare side effects sometimes do not appear in smaller groups) and effectiveness of the candidate vaccine.

In the Regulatory review and approval stage, if a vaccine passes through all three phases of clinical development, the vaccine developer submits a Biologics License Application (BLA) to the FDA. Then Major drug manufacturers provide the infrastructure, personnel, and equipment necessary to create mass quantities of vaccines. They also reap the profits of successful or widely distributed drugs. During quality control the approval and distribution are far from the end of the line. Stakeholders must adhere to procedures that allow them to track whether a vaccine is performing as anticipated. These processes, however, cannot happen without the skills and input of numerous stakeholders, from lab researchers to policymakers to medical professionals.


In conclusion, vaccines are developed, tested, and regulated in a remarkably similar manner to other drugs. In general, vaccines are even more thoroughly tested than non-vaccine drugs because the number of human subjects in vaccine clinical trials is usually greater. In addition, post-licensure monitoring of vaccines is closely examined by the Centres for Disease Control and the FDA. Which is why it takes 10-15 years to develop a vaccine that is effective and safe.

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