Many experts say a return to normalcy is impossible without a vaccine. How close are we? Let’s look at the process.

The world awaits a COVID-19 vaccine.
The world awaits a COVID-19 vaccine.
Image by Ri Butov from Pixabay

The current COVID-19 pandemic affects all of us in both direct and indirect ways. When will distancing guidelines and travel restrictions be eased? Vaccine development efforts are well underway but any such drug must be both safe and effective.

Where do things stand? First, it may be helpful to understand how these therapies are designed and developed. Let’s discuss the drug development process to discover how close we may be to a COVID-19 vaccine.

1. Know Your Mission

What Is the COVID-19 Vaccine?

A COVID-19 vaccine will trigger our immune system to produce antibodies that will protect us when exposed to the virus. In this way, it will prevent COVID-19 from spreading within our bodies and protect those around us.

A successful COVID-19 vaccine must be efficient, effective, and safe.

Where Do We Start?

First, we must understand the structure of COVID-19 virus.

Structures that trigger our immune system are known as antigenic structures. To design an effective vaccine, you need to select the most appropriate antigenic structures, which can be determined by conducting exploratory studies or through a review of the scientific literature.

The video below highlights COVID-19 structures.

Effective vaccines are based on the structure of the virus being targeted.
Scientific Animations, Medical Animation Coronavirus Structure 200130, January 30, 2020.

Reported Antigenic COVID-19 Structures

Researchers have identified several COVID-19 structures capable of triggering our immune system. They include:

  • Spike glycoprotein (S)
  • Nucleocapsid protein (N)
  • Non-structural proteins (nsp3, nsp8)
  • Nucleic acid (RNA)

You can return to the video to view them.

We Have Our Target, What’s Next?

How to extract and deliver your targeted antigenic structure.
How to extract and deliver your targeted antigenic structure.
Photo by Anna Shvets from Pexels

As part of this step, scientists decide on the most suitable way to deliver the vaccine. The available methods include:

  • Introducing the complete viral structures after attenuating or inactivating it. This gives you a live-attenuated or inactivated vaccine.
  • Introducing a specific viral structure, making a subunit, or recombinant vaccine.
  • Introducing the specific part of viral protein that triggers our immune system “peptide”. This gives you a peptide-based vaccine.

From here, we design our probable “candidate” vaccine.

2. We’ve Designed Our Candidate Vaccine, Now What?

At this point, we need to prove that our candidate vaccine will protect us.

This means conducting experimental studies to gather sufficient evidence. Specifically, we’ll study the ability of our candidate vaccine to:

  • Trigger our immune system (efficacy)
  • Not harm us through side effects (safety)

How Can We Prove That Our COVID-19 Vaccine Is Successful?

As mentioned previously, you must conduct experimental studies for your candidate vaccine.

Before we can begin studying the effects of the vaccine in humans, we must test the safety and efficacy of it in experimental animals. The studies include:

  • Tests in experimental animals (pre-clinical trials)
  • Tests in humans (clinical trials)

Pre-Clinical Trials

Before you start your animal testing, you need a “clearance” from your institution’s ethics committee.

Next, you’ll select suitable experimental animals like rats and monkeys. Then, you give them your candidate vaccine. You’ll see if they form enough COVID-19 antibodies and observe the side effects.

The pre-clinical studies help you determine safety, efficacy, and toxicity issues, as well as identify approximate dose levels.

Once you achieve reasonable results, you can proceed to the next step.

Clinical Trials

Giving candidate COVID-19 vaccine to humans
Giving the candidate COVID-19 vaccine to humans.
Image by Pete Linforth from Pixabay

Since clinical trials involve humans, you need “informed consent” from the participants. Also, you need approval from regulatory agencies, including the U. S Food and Drug Administration (FDA) and the European Medicines Agency (EMA).

Clinical trials include four stages, or phases. I’ve summarized them for you below.

PhaseParticipants numberAim
Phase 1a small group of healthy volunteers (up to 100)To assess the safety, efficacy, and the preliminary dose level
Phase 2different populations (up to 1000)To get more information about the efficacy and safety, and to know the largest safe dose
Phase 3larger populations including control group (several thousand)To get clear information about safety, efficacy, and side effects at the optimal dose
Phase 4Whole marketTrack your licensed vaccine in the market. To ensure its efficiency and record its long-term side effects if appeared
Table 1 Clinical trials phases

After you complete Phase 3, you can apply for a “biological license.” If the regulatory organization approves your application, you’ll have the right to license, manufacture, and market your vaccine.

3. What Else Should I Know?

Before Entering the Market

There are many steps in the development of a vaccine.
There are many steps in the development of a vaccine.
Photo by Chokniti Khongchum from Pexels

Since your target is the entire world population, you need to extend your production line. This will allow you to make enough doses to cover everyone.

Estimated Time to Get a Successful COVID-19 Vaccine?

You may notice that the journey to a successful COVID-19 vaccine involves many steps. You’d do them rigorously to ensure safety and efficacy.

On a normal track, it may take up to 15 years to deliver a vaccine. But, given the urgent nature in this case, a fast-track strategy is allowed, shortening the timeline to 12-18 months.

Current COVID-19 Vaccines Under Development

There are more than 100 candidate vaccines under development. They encompass:

  • 137 candidates in the pre-clinical stages
  • 23 candidates in the early stages of clinical trials

In the table below, I have listed those in Phase 3 clinical trials.

NameTypeDeveloperApproximate participants number
AZD1222Recombinant vaccineUniversity of Oxford and AstraZeneca company30,000
Bacillus Calmette-Guerin (BCG)Live-attenuated vaccineUniversity of Melbourne, Murdoch Children’s Research Institute, Radboud University Medical Center, Faustman Lab at Massachusetts General Hospital10,000
BNT162Subunit (modified mRNA)Pfizer and BioNTech companies30,000
CoronaVac inactivated vaccineSinovac Company9,000
Inactivated vaccineInactivated vaccineWuhan Institute of Biological Products and China National Pharmaceutical group15,000
mRNA-1273Subunit vaccineModerna biotechnology company, and the U.S National Institute of Health30,000
Table 2 Candidate COVID-19 vaccines in phase 3 clinical trials


  1. Employing drug delivery strategies to create safe and effective pharmaceuticals for COVID-19
  2. COVID-19 Vaccines: A Race Against Time in the Middle of Death and Devastation!
  3. COVID-19: A Review of Emerging Preventative Vaccines and Treatment Strategies
  4. SARS-CoV-2 (COVID-19) Vaccine Development and Production: An Ethical Way Forward
  5. Rapid development and deployment of high‐volume vaccines for pandemic response
  6. COVID-19 vaccine design: the Janus face of immune enhancement
  7. World Health Organization DRAFT landscape of COVID-19 candidate vaccines
  8. The University of Melbourne, SARS lessons for COVID-19 vaccine design
  9. Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2: a preliminary report of a phase 1/2, single-blind, randomized controlled trial
  10. COVID-19 vaccine tracker
  12. NIH clinical trial of investigational vaccine for COVID-19 begins
  13. Ongoing Trails for Bacille Calmette-Guerin (BCG) Vaccines in the prevention of COVID-19
  14. The COVID-19 Live Vaccine Tracker, Contagion Live Infectious Disease Today