Public/Global Health

What you need to know about four potential COVID-19 vaccines

The coronavirus pandemic has set off an unprecedented global scramble for a vaccine.

There are more than 100 potential vaccine candidates, according to the World Health Organization, but only eight have entered the crucial clinical trials stage. Four are in the United States and Europe, with the rest in China.

“I can never remember anything like this,” Walter Orenstein, associate director of the vaccine center at Emory University in Atlanta, said of the number of vaccines being developed to tackle one disease. “Hopefully, at least one and hopefully more than one will prove to be safe and effective.”

None have yet gone through the full trials needed to show that they are safe and effective.

While a range of extraordinary measures — imposing stay-at-home orders, testing millions of people, wearing masks and social distancing — can help slow the spread of the virus, experts say the key to getting completely back to normal is having a safe and effective vaccine that’s widely available.

Some researchers involved in the process say that in a best-case scenario, the first doses of a vaccine could be ready in September or October — far faster than any vaccine has ever been developed. The process usually takes years.

President Trump is projecting confidence on getting a vaccine quickly, saying it’s a top priority.

“We think we’re going to have a vaccine by the end of this year,” he said at a Fox News town hall last week. “And we’re pushing very hard.”

The U.S. vaccine efforts are more likely to be made available to Americans first.

New technologies are helping speed the process along at a rate much faster than the traditional method of giving someone a weakened version of the virus. For example, new technology uses RNA or DNA to code for a part of the virus to trigger an immune response that offers protection. But that technology has never been used on a wide scale for an approved vaccine, adding to the uncertainty.

And given the logistical challenges of mass production, some companies are already preparing to ramp up manufacturing for millions of doses, even before knowing whether their potential vaccine is effective.

Here’s a guide to the four U.S. and European vaccine efforts that have started clinical trials.

Oxford University-AstraZeneca

Some of the highest hopes, and the most ambitious timeline, come from researchers at Oxford University, who are now working alongside British pharmaceutical giant AstraZeneca.

“The aim is to have at least a million doses by about September, once you know the vaccine efficacy results and then move even faster from there,” Oxford professor Adrian Hill told the BBC last month.

The potential vaccine began testing in healthy volunteers in a Phase I clinical trial late last month at five sites in England. Data from that trial could be available this month, and later-stage trials could start by the middle of the year, AstraZeneca said on April 30.

The potential vaccine has had success in preventing coronavirus in rhesus macaque monkeys during a test at a National Institutes of Health (NIH) lab in Montana, The New York Times reported last month. It works by using a weakened version of a different virus known as adenovirus, which causes infections in chimpanzees, to deliver genetic material of part of the coronavirus into the body. The body then would generate an immune response to the section of the coronavirus, providing protection.


The Massachusetts biotech company Moderna Inc. is partnering with Anthony Fauci’s team at the NIH on another leading vaccine candidate.

Moderna announced Tuesday that the Food and Drug Administration (FDA) has given the firm fast-track designation, a move designed to expedite the development of treatments for life-threatening diseases, such as COVID-19.

Last week, the company said it would begin a Phase II study with 600 people “shortly” and plans to start a Phase III trial with thousands of people by “early summer.”

Stéphane Bancel, the company’s CEO, told CNBC that the process is progressing at an unexpectedly fast clip.

“It has gone faster than my best-case scenario back in January,” Bancel said. “When we started this back on Jan. 11, partnering with the team of Dr. Tony Fauci, we were hoping to get in the clinic in the summer.”

Instead, Phase I clinical trials started on March 16, and Phase II trials are about to begin.

He said his employees have been “working long days, working seven days a week since January,” and collaborating closely with the NIH and FDA.

Through a partnership with the Swiss biotech company Lonza, manufacturing of the vaccine could start as early as July, Bancel said, even before trials are complete.

Still, he acknowledged that vaccine candidates worldwide “will all be supply constrained for quite some time, meaning we won’t be able to make as many products as will be required to vaccinate everybody on the planet.” He anticipates working with governments to decide how to allocate the first doses, for example to health care workers and first responders.

This potential vaccine works differently than the Oxford one. It uses messenger RNA (mRNA) to deliver the genetic code for part of the coronavirus, which then provokes a response from the body’s immune system, offering protection.


Pfizer and the German company BioNTech are also working together on a potential vaccine using mRNA.

They are testing four potential vaccines at once, using different formats of mRNA to see which one works best.

The companies last week announced they had begun a Phase I trial with up to 360 people at sites including New York University and the University of Maryland.

Mikael Dolsten, Pfizer’s chief scientific officer, told CNBC that the company expects to produce “millions of doses” by October, with plans for “tens of millions” later this year and “hundreds of millions” in 2021.

“So it’s a very quick plan,” Dolsten said.

Pfizer, a drug manufacturing powerhouse, said it has selected its facilities in Massachusetts, Michigan and Missouri, along with one in Belgium, to be the initial manufacturing centers for the vaccine.


The biotech company Inovio is working on a potential vaccine that uses DNA rather than RNA to code part of the coronavirus and produce an immune response.

The company says its DNA vaccines can be produced faster and stored more easily, in addition to being safer than other types. This vaccine would require an added step of a hand-held device to deliver an electrical pulse that helps the vaccine enter human cells.

Inovio announced at the end of April that it had enrolled 40 people in its Phase I study at the University of Pennsylvania and a clinic in Kansas City. Interim results are expected by June and further stages of trials could start this summer, the company said.

“If we are on track, this could be as early as by the end of this year or early next year,” Inovio CEO J. Joseph Kim told The Hill when asked when the first doses of vaccine could be ready for the public.

He said it is “quite a challenge” to be able to scale up manufacturing a “thousandfold” to produce hundreds of millions of doses and that more funding from the federal government would help.

“More funding and resources will help us scale up to a larger manufacturing scale,” he said.

Kim acknowledged the skepticism about his company, namely that it has never had a product approved by the FDA.

But the company has shown promising results in other areas like the MERS virus and cervical cancer, Kim argued.

“I think healthy skepticism is always fair,” he said. 

Ultimately, the results of the COVID-19 trials will have to show the coronavirus vaccine is effective.

“I think proof should be in the pudding,” he said.

Updated at 11:28 a.m.

Tags Anthony Fauci Clinical trials Coronavirus COVID-19 Donald Trump Pandemic Vaccine
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