How Long Does It Take to Develop a Vaccine?
With the coronavirus pandemic still threatening billions of people around the world, hope for a vaccine is never far from people’s minds. Modern science accomplishes amazing feats on an ongoing basis. It’s certainly understandable to wonder why scientists can’t come up with a fast, reliable solution to stop the spread of the virus. The answer is complicated.
Biotech and pharmaceutical companies like Moderna, Inovio, Pfizer and Merck as well as research universities like Oxford in the U.K. have all launched emergency fast-track development approaches and clinical trials to create a successful coronavirus vaccine, but certain safeguards simply can’t be skipped in the interest of public safety. Although COVID-19 continues to take lives on a daily basis, a rushed vaccine that isn’t properly tested could ultimately prove to be just as dangerous as the virus.
We need a coronavirus vaccine quickly, but we need it to be safe, not just today but for our long-term health. To better understand the challenges scientists are up against, let’s take a look at how long it normally takes to develop a safe, effective vaccine and the timeline we can reasonably expect from emergency government authorizations granting faster development.
Stages of Vaccine Development
According to guidelines established by the CDC, vaccines pass through six general stages of development: exploratory, pre-clinical, clinical, regulatory review and approval, manufacturing, and quality control. The full process is essentially the same as the process for any drug approved for use in the United States. These stages are mandated by the Food and Drug Administration (FDA), with its Center for Biologics Evaluation and Research (CBER) division officially in charge of regulating vaccines. It’s not unusual for a vaccine to take 10 to 15 years to complete all the phases under normal circumstances.
Laboratory research and testing makes up the beginning stage of vaccine development. In this phase, scientists from the academic sector, government sector or private sector try to identify natural or synthetic antigens that could either protect the human body from the target disease or at least help the body fight the disease. Different vaccine approaches can be used to establish immunity, and it takes time in this phase to determine which type will work best. For example, some vaccines contain mild strains of live virus, while others use inactive viruses to trigger immunity. The exploratory stage often takes two to four years to complete, with many vaccine ideas abandoned along the way.
Once a potential vaccine has been developed, researchers start pre-clinical studies using animal testing to evaluate the immune response created by the vaccine. Animal studies usually involve monkeys due to their biological similarities to humans but often first begin with mice or rats. As the research progresses, researchers may inject animals with the vaccine and then attempt to infect them with the target virus. The goal of the studies is to determine the potential cellular reaction humans could have to the vaccine.
Clinical Stage: Phase 1
As with any drug, clinical development of a vaccine takes place in three phases. The first phase involves a relatively small group of healthy test subjects, usually between 20 and 100 people. Although children are often the intended recipients of vaccines, only adults participate in the earliest phase of testing. The trials are sometimes blind — recipients don’t know if their doses are real — and they sometimes involve challenge studies, which require researchers to deliberately attempt to infect subjects with the virus after giving them the vaccine. Researchers carefully control the "infection" process and closely monitor participants’ reactions. The full potency of a virus may not be used, for example.
Clinical Stage: Phase 2
During Phase 2 human clinical trials, researchers focus on a larger group of test subjects — usually numbering in the hundreds — that fit the criteria of the average vaccine recipient. That includes using younger test subjects for vaccines intended for children and older test subjects for those intended for the elderly. The trials are controlled, random and use a placebo vaccine for some participants.
Clinical Stage: Phase 3
By the time it reaches a Phase 3 clinical trial, a vaccine has already proven its effectiveness — and its potential side effects — among a few hundred people, but it’s still important to learn whether those results can be considered reliable among the larger population. Phase 3 trials usually involve thousands of people. Testing protocols are random and double blind — neither researchers nor participants know if doses are placebo — at this phase. Placebos could be anything from saline solutions to other helpful vaccines.
Regulatory Review and Approval
After completing the final phase of human clinical trials, researchers can submit a Biologics License Application (BLA) to the FDA to request approval to produce the vaccine and distribute it. A special team of scientists and medical professionals at the FDA will evaluate the results of all the clinical findings in all the previous trials and make an approval decision based on the risks versus the benefits of the vaccine. Before making a final decision, they also order an inspection of the factories that will produce the vaccine. Labeling for the vaccine also follows strict guidelines and requires approval.
FDA monitoring of the vaccine doesn’t end when a license is issued for a vaccine. The agency monitors the manufacturing process and the manufacturer’s testing protocols to ensure safety by making sure vaccines aren’t contaminated and deliver consistent potency. Manufacturers are always subject to facility inspections, and the FDA can also conduct its own testing on vaccine samples at any point.
In addition to ongoing facility inspections and vaccine testing, various protocols are put in place to ensure the ongoing quality and safety of vaccines after their approval. In some cases, researchers may choose to continue with Phase 4 clinical trials, usually for the purpose of determining other potential uses for the vaccine or to pinpoint ways to further enhance its effectiveness or eliminate side effects.
Emergency Protocols and Approvals
As soon as the world really understood the reality of the novel coronavirus pandemic and the threat it posed, the CDC, the World Health Organization (WHO) and other country-based health organizations around the world were bombarded with questions — and demands — about how long it would take to develop a vaccine for the virus. Obviously, hearing that a vaccine following a normal track could take more than a decade to hit the market is more than a little alarming when large numbers of people are dying, and the world is in need of protection.
Current Coronavirus Vaccine Development
People around the world are currently waiting on the edge of their seats for the development of a coronavirus vaccine. In May 2020, the first glimmer of hope bubbled up when U.S. biotech company Moderna released data from its Phase 1 human trial. The results were mostly considered positive, with the vaccine protecting mice from lung infections and creating an immune response in humans. Since then, other research teams have started releasing information about their early clinical findings and progress.