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Fall 2020
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From lab to community immunity

Three paths to a vaccine for COVID-19

By Justin Harris
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Marc Jenkins, Ph.D., has an optimistic prediction about COVID-19: “We’ll have a vaccine soon,” he says. “I think next year.”

Since the pandemic began, Jenkins, who directs the University’s Center for Immunology and is a Regents and Distinguished McKnight University Professor in the Medical School Department of Microbiology and Immunology, had his finger on the pulse of vaccine development efforts the world over, including at his own institution.

More than 100 vaccine projects in various stages across the globe take subtly different approaches to achieving the same goal: trigger the body’s immune response to COVID-19 before the virus has an opportunity to spread and cause harm.

Vaccines teach the body how to make the specialized proteins, known as antibodies, that are needed to defeat a virus. Once a person has these antibodies, they usually stay in that individual’s blood for life, creating immunity to the virus moving forward.

Some viruses, like influenza, are able to mutate, which is why we have to get a different flu shot every fall, says Jenkins, who was elected to the prestigious National Academy of Sciences earlier this year.

Luckily, he says, COVID-19’s mutating powers appear to be limited.

“Thanks to vaccines, we’ve come close to eradicating other diseases entirely, like polio,” he says. “Most of what I see in COVID-19 tells me it’s like that.”

Click on the numbers below to find out how a few of the most promising approaches work.

ILLUSTRATION BY ANDREW BAKER

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But first, infection without a vaccine

Without antibodies, cells are susceptible to COVID-19 infection. This happens when the virus’ spike proteins latch onto a lung airway cell’s surface protein, unlocking the cell’s front door and allowing the virus to enter, replicate itself, and cause damage.

When the body detects COVID-19, it develops antibodies, which attach to the virus’ spike proteins and prevent the virus from infecting cells.

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Virus vaccines

This type of vaccine introduces a dead or weakened version of the COVID-19 virus to the body. The dead or weakened virus is relatively harmless to the person, but the immune system treats it as a real threat and begins to produce antibodies. This is how most flu vaccines work.

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Subunit vaccines

Instead of using the entire virus, these vaccines use only a part of it. Some vaccines in development inject the virus’ DNA or RNA—a kind of instruction manual for creating the spike protein—into the body’s host cells. The body’s cells use those instructions to create the spike protein. The protein is harmless without the rest of the COVID-19 virus, but the immune system doesn’t care and creates antibodies, anyway.

Other potential vaccines would involve injecting the spike proteins directly, which would also cue the body to create antibodies.

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The “Plan B” vaccine

Jenkins is confident that either a virus vaccine or a subunit vaccine will prove successful against COVID-19 by inducing antibodies. But he and his team aren’t taking any chances. That’s why they’re working on what he calls the “Plan B” vaccine, one that takes a different approach entirely.

Instead of focusing on the immune system’s antibodies, his team’s vaccine would harness the power of a different type of defense system known as T lymphocyte cells. In this form of a vaccine, a person’s T cells would be specially trained to identify COVID-19’s spike proteins and destroy any cell that has them.  “It’s kind of like bombing the factories creating the virus,” he says.

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Fast-tracking hope

Creating a vaccine is a typically long and winding process, taking many years, sometimes decades, Jenkins says. But COVID-19 and its worldwide impact make this vaccination pursuit different.

“I think we’re going to see this thing really, really move fast—faster than people think,” he says. “We’re going to see an unprecedented mobilization to get the vaccine into people.”

Here’s what needs to happen between a promising lab discovery and a vaccine becoming widely available.

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Clinical testing

The clinical trial process includes three phases, each of which tests a larger group of people than the one before it. These steps make sure the vaccine is safe and well-tolerated, determine the ideal dose, and, of course, test whether the vaccine serves its intended purpose.

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Approval

If a vaccine proves safe and effective, the U.S. Food and Drug Administration would approve it for wider use.

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Production

Then the vaccine would be mass-produced in specialized factories across the country and globe. Jenkins says the National Institutes of Health is already preparing these facilities.

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Prioritization

Typically among the first to receive a new vaccine would be people at the highest risk of severe complications. That would include older people in shared nursing facilities, people with compromised immune systems, and those with underlying conditions, as well as frontline health care workers. But the best COVID-19 vaccination strategy is still under discussion.


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