our bodies and healthcare systems are left vulnerable.

In times like these, there's an urgent need for a vaccine

to create widespread immunity with minimal loss of life.

So how quickly can we develop vaccines when we need them most?

Vaccine development can generally be split into three phases.

In exploratory research, scientists experiment with different approaches

to find safe and replicable vaccine designs.

Once these are vetted in the lab, they enter clinical testing,

where vaccines are evaluated for safety, efficacy, and side effects

across a variety of populations.

Finally, there's manufacturing,

where vaccines are produced and distributed for public use.

Under regular circumstances, this process takes an average of 15 to 20 years.

But during a pandemic, researchers employ numerous strategies

to move through each stage as quickly as possible.

Exploratory research is perhaps the most flexible.

The goal of this stage is to find a safe way

to introduce our immune system to the virus or bacteria.

This gives our body the information it needs to create antibodies

capable of fighting a real infection.

There are many ways to safely trigger this immune response,

but generally, the most effective designs are also the slowest to produce.

Traditional attenuated vaccines create long lasting resilience.

But they rely on weakened viral strains

that must be cultivated in non-human tissue over long periods of time.

Inactivated vaccines take a much faster approach,

directly applying heat, acid, or radiation to weaken the pathogen.

Sub-unit vaccines, that inject harmless fragments of viral proteins,

can also be created quickly.

But these faster techniques produce less robust resilience.

These are just three of many vaccine designs,

each with their own pros and cons.

No single approach is guaranteed to work,

and all of them require time-consuming research.

So the best way to speed things up is for many labs

to work on different models simultaneously.

This race-to-the-finish strategy

produced the first testable Zika vaccine in 7 months,

and the first testable COVID-19 vaccine in just 42 days.

Being testable doesn't mean these vaccines will be successful.

But models that are deemed safe and easily replicable

can move into clinical testing while other labs continue exploring alternatives.

Whether a testable vaccine is produced in four months or four years,

the next stage is often the longest and most unpredictable stage of development.

Clinical testing consists of three phases, each containing multiple trials.

Phase I trials focus on the intensity of the triggered immune response,

and try to establish that the vaccine is safe and effective.

Phase II trials focus on determining the right dosage and delivery schedule

across a wider population.

And Phase III trials determine safety

across the vaccine's primary use population,

while also identifying rare side effects and negative reactions.

Given the number of variables and the focus on long-term safety,

it's incredibly difficult to speed up clinical testing.

In extreme circumstances, researchers run multiple trials

within one phase at the same time.

But they still need to meet strict safety criteria before moving on.

Occasionally, labs can expedite this process by leveraging

previously approved treatments.

In 2009, researchers adapted the seasonal flu vaccine to treat H1N1—

producing a widely available vaccine in just six months.

However, this technique only works when dealing with familiar pathogens

that have well-established vaccine designs.

After a successful Phase III trial, a national regulatory authority

reviews the results and approves safe vaccines for manufacturing.

Every vaccine has a unique blend of biological and chemical components

that require a specialized pipeline to produce.

To start production as soon as the vaccine is approved,

manufacturing plans must be designed in parallel to research and testing.

This requires constant coordination between labs and manufacturers,

as well as the resources to adapt to sudden changes in vaccine design—

even if that means scrapping months of work.

Over time, advances in exploratory research and manufacturing

should make this process faster.

Preliminary studies suggest that future researchers

may be able to swap genetic material from different viruses

into the same vaccine design.

These DNA and mRNA based vaccines could dramatically expedite

all three stages of vaccine production.

But until such breakthroughs arrive,

our best strategy is for labs around the world to cooperate

and work in parallel on different approaches.

By sharing knowledge and resources,

scientists can divide and conquer any pathogen.