A leading potential coronavirus vaccine just started human trials in the US. The top scientist at Pfizer told us it could be ready for emergency use this fall.

A set of promising potential coronavirus vaccines just started trials in healthy volunteers in the US. If one of the injections works, the developers said they aim to make it available this fall.

The first trial participants were given the vaccines at the medical schools of New York University and the University of Maryland, the vaccine’s developers, Pfizer and BioNTech, said in a statement.

Mikael Dolsten, Pfizer’s chief scientific officer, told Business Insider in an interview that the testing plan could allow for emergency use or accelerated approval this fall. Dolsten acknowledged the unprecedented nature of this timeline for vaccine development, a process that typically requires multiple years of studies. 

“I don’t think this has ever happened in the history of modern vaccines,” Dolsten said, adding that nothing in his three decades of working in the drug industry matches the speed of this program. 

Pfizer, a top drugmaker with a market value north of $200 billion, is leading the research in collaboration with the smaller biotech BioNTech. The human study is simultaneously testing four vaccine candidates at various dose strengths.

There are more than 100 coronavirus vaccines in development, with at least 20 expected to start human testing in 2020. The urgency of the pandemic has pushed drugmakers to reconsider the typical, multiyear timeline of vetting a vaccine before widespread use.

All four Pfizer-BioNTech vaccines were developed using the messenger RNA (mRNA) platform, an unproven vaccine technology that has taken center stage in the sprint for a coronavirus cure. The technology is marked by its speed, requiring just the genetic code of the virus to build a vaccine candidate.

But mRNA has yet to produce an approved vaccine, leaving COVID-19 as a real-time test of the technology on the biggest possible stage.

The Massachusetts biotech Moderna is also testing an mRNA coronavirus vaccine candidate, which was the first to enter the clinic earlier this year. Moderna is eyeing the potential for emergency use this fall as well.

For now, both vaccine programs remain in the earliest stages of human testing. Pfizer and Moderna are both expecting initial trial results focused on safety in the next month or so. 

Pfizer is preparing for emergency use this fall

Researchers are also now vaccinating primates with Pfizer’s vaccine and then exposing them to the virus to see if they get infected. Dolsten said this work could support the vaccine and also help answer what immune response is required to protect people.

Researchers will measure the primates’ blood for the level of antibodies needed to protect from disease.

“It gives you a very nice surrogate,” Dolsten said. “If you have a similar level in humans vaccinated, it’s quite reasonable to assume it protects humans.”

The US human trials are part of a program also recruiting volunteers in Germany. The University of Rochester and Cincinnati Children’s Hospital Medical Center will soon start enrolling volunteers for the study alongside the University of Maryland and NYU. The US study aims to recruit 360 healthy volunteers ranging from 18 to 85 years old.

Initial human results and strong data showing the vaccine works in animals could build the case for broader use in the fall.

A potential emergency use would likely depend on the dynamics of the pandemic, Dolsten said. 

For instance, imagine a city at the epicenter of a fall outbreak. Pfizer could vaccinate the northern part of that city, wait a couple months, and then immunize the other half, assuming they have similar populations, Dolsten said.

That approach would not only collect data on tens of thousands of people, clarifying the benefits and risks from the experimental vaccine, but it could help address a public health crisis in real time. 

Using a so-called surrogate endpoint, like the level of neutralizing antibody that people develop after getting an injection, could allow research to enter this phase of testing “many months earlier,” Dolsten said. Researchers would still want to see that the vaccine prevents people from getting infected, which additional studies would determine.

Others have cautioned that there are many unknowns surrounding the immune response to this virus. While animal data may suggest protection from a certain level of antibodies, that isn’t necessarily proof it will protect humans.