I. Is a COVID-19 vaccine available?

Note: For the latest on coronavirus vaccines, visit this tracker created by the New York Times.

Since the COVID-19 pandemic began, one of the biggest questions is how quickly researchers can develop a vaccine for the deadly disease.

Part of what makes COVID-19 so contagious and dangerous is that it is a new illness against which humans have no natural immunity. Therefore, a COVID-19 vaccine is essential to preventing the spread of the illness, and limiting its severity when people become infected.

Vaccine development typically takes 9-15 years. To date, the fastest vaccine development was the mumps vaccine, which took four years. Because of the urgency and severity of this pandemic, researchers are working to develop a vaccine as quickly as possible. There are more than 155 vaccines in various stages of development, only nine months after the first known case of COVID-19.

Despite this speed, there is no definitive timeline for when a COVID-19 vaccine will be available. Many experts believe that an effective vaccine is possible by mid-2021, but acknowledge that is an optimistic estimate. There are many challenges in vaccine development that make the 12-18 month timeframe unlikely.

What is a vaccine?

When a person is vaccinated, their immune system develops antibodies against a disease, so that when they come in contact with it, their body knows how to properly fight it.

Although the human immune system can defend against most common germs, for unfamiliar diseases like COVID-19, vaccines are essential to providing protection that our bodies cannot produce on their own.

II. How long does it take to develop a vaccine?

There are four stages of vaccine development:

Stage 1: Exploratory

The preliminary stage in which researchers learn about the disease, and start identifying ways to prevent it. It typically lasts 2-4 years, but is moving much more rapidly with COVID-19.

Stage 2: Preclinical Testing

Scientists give a vaccine candidate to animals like mice or monkeys to see if it produces an immune response. While this stage usually takes 1-2 years, there are currently over 135 COVID-19 vaccine candidates in preclinical testing. A significant number of vaccine candidates do not make it past this point.

Stage 3: Clinical Development

This three-phase stage is the most critical part of the process, when scientists test the vaccine in humans.

  • Phase I Safety Trials: Scientists give a vaccine candidate to a small group of people (typically less than 100) to test safety and dosage, and confirm that it stimulates an immune response in humans. Under normal circumstances, this phase lasts 1-2 years, but there are currently 15 COVID-19 vaccine candidates in Phase I.
  • Phase II Expanded Trials: Hundreds of people, split into groups like children and the elderly, receive the vaccine candidate to see if and how the vaccine acts among different groups, further testing its safety and efficacy. Usually lasting 2 years, there are currently 11 COVID-19 vaccine candidates at this phase. In the case of COVID-19, many labs are combining Phases I and II to accelerate the development process.
  • Phase III Efficacy Trials: This is the largest testing phase, with thousands of people receiving the vaccine. Scientists then wait to see how many people become infected, compared to other participants who receive a placebo. This long-term testing determines if the vaccine will actually protect against the disease it seeks to prevent. It can last anywhere from 3-15 years, but at this time, there are four COVID-19 vaccine candidates in Phase III.

Stage 4: Approval

If a vaccine candidate makes it through all these stages, regulators in individual countries review the trial results, and determine whether to approve the vaccine for use in their country. This is also a time-consuming process, but in the case of a pandemic, a vaccine may receive emergency use authorization before formal approval. There is currently one COVID-19 vaccine approved for limited use in China.

III. Types of COVID-19 vaccines in development

Here are some of the different types of vaccines being tested for COVID-19:

  • Whole-virus vaccines, which use a weakened or inactivated version of the disease to stimulate an immune response. This is the most common type of vaccine.
  • Genetic vaccines, which use one or more of the virus’s own genes to stimulate an immune system response. To date, no vaccine built using this method has successfully passed through clinical trials to gain approval.
  • Viral vector vaccines, which provoke an immune response by delivering COVID-19 genes into cells using a virus. Currently the only COVID-19 vaccine with limited approval is a viral vector vaccine.
  • Protein-based vaccines, which provoke an immune response using a coronavirus protein or protein fragment.
  • Repurposed vaccines, in which an existing vaccine is repurposed for use against COVID-19.

IV. Challenges of developing a COVID-19 vaccine

Scientists racing to create a vaccine against COVID-19 face several challenges, some of which are common in the vaccine development process, and some of which are unique to this situation.

The newness of the disease presents an obstacle, as scientists must first understand a disease, before they can find an effective way to inoculate against it.

Another issue is safety. Scientists must ensure that vaccines work properly, and that they won’t cause any side effects that are equally or more damaging than the disease it is trying to prevent.

This is one of the reasons why there are many regulations in place when it comes to vaccine development, and why the process usually takes years. Scientists must be able to see the long-term effects of a vaccine, to confirm that it is safe for widespread use. Currently, scientists are balancing the urgent need for a COVID-19 vaccine with the necessary precautions to make sure it is safe and effective.

Lastly, once an effective COVID-19 vaccine is approved, there is the final step of manufacturing and distributing the vaccine. Pharmaceutical companies around the world are already gearing up to manufacture millions of doses as soon vaccines are approved, although some types of vaccines, like whole-virus vaccines, will be easier than others to produce on a mass scale because the infrastructure already exists.

V. Additional Resources

Name Website Summary
Centers for Disease Control and Prevention (CDC) https://www.cdc.gov/coronavirus/2019-ncov/index.html The CDC is the United States’ leading national public health organization. Its mission is to protect public health and safety through the control and prevention of disease, injury, and disability in the U.S. and abroad.
World Health Organization (WHO) https://www.who.int/ A specialized agency of the United Nations, WHO is responsible for international public health. Headquartered in Geneva, Switzerland, it has field offices worldwide.
Association of Public Health Laboratories (APHL) www.aphl.org The APHL is a nonprofit organization in the United States that represents laboratories that protect public health and safety.

VI. Sources