Feature Article: Why Will It Take So Long to Make a Vaccine against COVID-19?

By now, most people are aware of the important role for vaccination in addressing the COVID-19 pandemic. Because this is a new virus, we do not have a vaccine to protect against it. And, while many scientists and companies around the globe have started to work on vaccine development, estimates suggest that the shortest timeframe for having a vaccine is next year. This has left many wondering, “Why will it take so long?”

To get a better sense of why it will take time — and why an estimate of one year is optimistic — it is useful to start with a discussion about how vaccines are made and how long it takes under normal circumstances, before looking at what will change because we are in the midst of a public health emergency and what that means for individuals and families.

Making vaccines under normal circumstances: The process and the timeline

Because vaccines are given to healthy people, they are among the best studied products available. Typically, vaccine development starts not at companies but rather in university labs, where scientists identify what type of vaccine they are interested in creating and what type of animal model will be useful for evaluating it. Animals, when infected, develop immune responses similar to people. Animal models are not perfect, but they offer an opportunity to study a vaccine candidate before it is given to people; these are called “proof-of-concept” studies. To learn more about working with animals in vaccine research, watch this short video.

With a candidate vaccine and some positive results in animals, vaccine development typically moves to a company. The potential vaccine goes through several phases of trials that include increasingly larger numbers of people. All phases carefully monitor vaccine safety, but as the studies progress, they move from evaluating immunogenicity, meaning the ability to generate an immune response in recipients, to efficacy, meaning the ability to protect recipients from infection. To find out more about these different stages of vaccine trials, visit the Vaccine Education Center’s (VEC’s) webpage, “Making Vaccines: Process of Vaccine Development.”

By the time these studies are done, tens to hundreds of thousands of people may have been inoculated with the vaccine. These studies can take 10 to 20 years or more to complete.

Making vaccines during a public health emergency

Obviously, during a public health emergency, we cannot wait for 10 to 20 years, so how does the process change?

First, in an emergency, it is likely that more resources will be put toward the project, so more scientists are able to work on developing a vaccine. For example, more than 70 companies are working on a COVID-19 vaccine, whereas under normal circumstances, fewer than five — and, often only one or two — companies are working on developing any particular vaccine. This means that all of those working on vaccine development can benefit from the findings of their competitors. This builds the knowledge base more quickly.

Second, researchers are able to work together with fewer barriers. For example, in the current COVID-19 pandemic, the World Health Organization (WHO) is overseeing an international randomized controlled trial in which candidate vaccines can be compared with a single placebo, or control, group. The plan is also written in a way that candidate vaccines can start being tested at different times, and data can be compared. In this way, the trial can help increase scientific rigor and efficient use of resources.

Third, normal processes are likely to be altered as well. This can include eliminating animal model studies, reducing the number of study participants at each phase, and shortening the timeline for monitoring results.

What does this mean for me and my family?

While people are anxious to resume regular activities, it is important that any vaccine against COVID-19 is safe and effective. Therefore, it is important to monitor what is happening with vaccine development, but it will be even more important for public health officials to clearly communicate what is known about any new COVID-19 vaccine in terms of how well it works and its possible side effects.

Likewise, other factors will also be important at that time. People will need to evaluate whether the disease is spreading in their area, whether they have immunity as a result of previous illness, what is known about how long immunity lasts, and whether a certain level of immunity is needed for protection.

With all of this information, public health officials will likely make vaccine recommendations, and families, in consultation with their healthcare providers, will need to decide the relative risks and benefits of being vaccinated.

Resources for more information

• Making Vaccines: Process of Vaccine Development, VEC webpage
• The Challenging Path to a COVID-19 Vaccine, Director of the VEC, Dr. Paul Offit, discussed COVID-19 vaccine development on Science Friday
• Update on WHO Solidarity Trial — Accelerating a safe and effective COVID-19 vaccine, WHO webpage
• Vaccine Testing and the Approval Process, Centers for Disease Control and Prevention (CDC) webpage