Typically, vaccine development takes years — sometimes decades.
Development of the COVID-19 vaccine is a different story, however. Since the pandemic began, it has been charging along at an unprecedented pace.
Impressively — less than a year later — the FDA granted Emergency Use Authorization (EUA) to two COVID-19 vaccines, the Pfizer and Moderna mRNA vaccines. Johnson & Johnson's viral vector COVID-19 vaccine followed only a few months later.
"The progress that researchers and pharmaceutical companies around the world have made toward developing effective COVID-19 vaccines is truly amazing," says Dr. H. Dirk Sostman, executive vice president and chief academic officer of Houston Methodist.
While it may seem like things have moved almost too quickly, rest assured that any vaccine made available to the public will have first been thoroughly tested and reviewed by experts.
"In particular, the gold standard test of a new vaccine — the randomized, placebo-controlled phase III clinical trial — is required by the FDA for considering approval of any new vaccine, regardless of how rapidly it has been developed," explains Dr. Sostman.
In fact, how fast a COVID-19 vaccine has been brought to the public has more to do with the vaccine development process itself.
Here are the four main reasons that COVID-19 vaccine development has progressed so rapidly:
Researchers were able to leverage previous coronavirus and vaccine research
The coronavirus that causes COVID-19 is indeed a new virus, but it's very similar to SARS and MERS — coronaviruses that previously made the jump from animals to people. This meant experts weren't starting completely from scratch when it came to quickly developing a vaccine.
"The first piece of information researchers needed was the genetic sequence of this new coronavirus, and the virus' genome was sequenced and made available by mid-January," says Dr. Sostman. "At that point, the genetic similarity between this new coronavirus and SARS, specifically, was noticed."
Before a clinical trial even begins, researchers use preclinical models to whittle down lists of potential vaccine targets. They're looking for the targets that elicit the strongest immune response with a good safety profile, and this can be a slow, grueling process.
Dr. Sostman explains that, because the SARS outbreak in 2003 was ultimately contained and there have been no outbreaks since, a SARS vaccine was never completed. But, vaccine strategies and potential targets — such as the now well-known spike protein — were identified before development stalled and funding dried up.
"The vaccine targets and strategies that came out of the SARS vaccine research is what we're benefiting from now," explains Dr. Sostman. "Given the genetic similarity between SARS and the new coronavirus, experts basically had a vaccine target cheat sheet — and manufacturers got to work immediately."
Having this leg up, so to speak, expedited vaccine development tremendously. It's what enabled Moderna to have a vaccine candidate ready for clinical trial testing as early as mid-March — just as the initial wave of infections was sweeping through major U.S. cities.
Hundreds of vaccine candidates are being developed and tested simultaneously
Another advantage we, as a global community, are benefiting from in terms of vaccine development is "the power of plenty."
"The sheer number of vaccine candidates for one specific disease is extraordinary," explains Dr. Sostman. "It's helping us make up for the trial-and-error process that often accompanies vaccine development."
Of these vaccine candidates, some use different targets, some use different technology — and having this level of diversity and saturation is a powerful position to be in during a pandemic.
"If one vaccine candidate isn't effective enough, it falls out of clinical trial — but a more effective one is likely right in its wake. If a vaccine has adverse effects, the clinical trial is immediately halted, but there's likely another vaccine right behind it that may have fewer side effects," explains Dr. Sostman. "This is a position we've never been in before when it comes to vaccine development."
Newer vaccine technology is being used
We've likely all heard by now that there's new technology being used in a few of the most promising COVID-19 vaccines — and we're talking first-in-human level of new.
Most of the vaccines you're used to hearing about typically require loads and loads of virus to first be produced. But mRNA vaccines and other new vaccine technologies don't.
Rather, these new classes of vaccines rely on material that can be synthesized in a laboratory — no virus needed. This, among other things, makes them very quick to develop. In addition, this technology should stand us in good stead if we encounter future mutations of the virus that make existing vaccine targets less effective.
"The science behind mRNA vaccines isn't new. This concept has been studied for a decade or more now," explains Dr. Sostman. "There have been challenges to overcome, but recent scientific breakthroughs have removed many of the hurdles that used to exist."
The other critical component of bringing these new types of vaccine to the public quickly is funding.
There is unprecedented financial support
A lack of sufficient funding — especially when the technology is new — can slow progress. But, given the need to take control of this pandemic, governments across the globe are financially backing the most promising vaccine candidates — the U.S. included.
"The tremendous financial support from the U.S. government is a huge reason a COVID-19 vaccine was brought to the public so quickly," says Dr. Sostman. "First, it allowed newer, faster vaccine technology to be used. Second, it's going to expedite vaccine distribution in a way we've never seen."
Typically, vaccine manufacturers wait to produce large quantities of a vaccine until after it's approved by the FDA. And, depending on the type of vaccine, this large-scale production can take months.
However, given the need to bring a safe, effective vaccine to the public so quickly, the U.S. government funded the manufacturing of several promising vaccines while these candidates were still in clinical trials. This removed the financial risk a vaccine manufacturer would have faced doing this on its own.
"Being able to manufacture large amounts of a vaccine so early on means it can be distributed shortly after it's approved by the FDA," says Dr. Sostman. "Instead of waiting months for millions of doses of a vaccine to be made, it's taken days to get these doses to hospitals."
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This article was updated on November 8, 2021 to reflect the current state of the COVID-19 vaccine landscape.