New vaccine in development could be cheap, effective
Anew vaccine for COVID-19 that is entering clinical trials in Brazil, Mexico, Thailand and Vietnam could change how the world fights the pandemic. The vaccine, called NDV-HXP-S, is the first in clinical trials to use a new molecular design that is widely expected to create more potent antibodies than the current generation of vaccines. And the new vaccine could be far easier to make.
Existing vaccines from companies like Pfizer and Johnson & Johnson must be produced in specialized factories using hard-to-acquire ingredients. In contrast, the new vaccine can be mass-produced in chicken eggs — the same eggs that produce billions of influenza vaccines every year in factories around the world.
If NDV-HXP-S proves safe and effective, flu vaccine manufacturers could potentially produce well over a billion doses of it a year. Low- and middle-income countries currently struggling to obtain vaccines from wealthier countries may be able to make NDV-HXP-S for themselves or acquire it at low cost from neighbors.
“That’s staggering — it would be a game-changer,” said Andrea Taylor, assistant director of the Duke Global Health Innovation Center.
First, however, clinical trials must establish that NDV-HXP-S actually works in people. The first phase of clinical trials will conclude in July, and the final phase will take several months more. But experiments with vaccinated animals have raised hopes for the vaccine’s prospects.
“It’s a home run for protection,” said Dr. Bruce Innis of the PATH Center for Vaccine Innovation and Access, which has coordinated the development of NDV-HXP-S. “I think it’s a world-class vaccine.”
The first wave of authorized COVID-19 vaccines require specialized, costly ingredients to make. Moderna’s RNA-based vaccine, for instance, needs genetic building blocks called nucleotides, as well as a custom-made fatty acid to build a bubble around them. Those ingredients must be assembled into vaccines in purpose-built factories.
The way influenza vaccines are made is a study in contrast. Many countries have huge factories for making cheap flu shots, with influenza viruses injected into chicken eggs. The eggs produce an abundance of new copies of the viruses. Factory workers then extract the viruses, weaken or kill them and then put them into vaccines.
The PATH team wondered if scientists could make a COVID-19 vaccine that could be grown cheaply in chicken eggs. That way, the same factories that make flu shots could make COVID-19 shots as well.
In New York, a team of scientists at the Icahn School of Medicine at Mount Sinai knew how to make just such a vaccine, using a bird virus called Newcastle disease virus that is harmless in humans.
For years, scientists had been experimenting with Newcastle disease virus to create vaccines for a range of diseases. To develop an Ebola vaccine, for example, researchers added an Ebola gene to the Newcastle disease virus’s own set of genes.
The scientists then inserted the engineered virus into chicken eggs. Because it is a bird virus, it multiplied quickly in the eggs. The researchers ended up with Newcastle disease viruses coated with Ebola proteins.
At Mount Sinai, the researchers set out to do the same thing, using coronavirus spike proteins instead of Ebola proteins. When they learned about a new version called HexaPro, they added that to the Newcastle disease viruses. The viruses bristled with spike proteins, many of which had the desired shape. In a nod to both the Newcastle disease virus and the HexaPro spike, they called it NDV-HXP-S.
PATH arranged for thousands of doses of NDV-HXP-S to be produced in a Vietnamese factory that normally makes influenza vaccines in chicken eggs. In October, the factory sent the vaccines to New York to be tested. The Mount Sinai researchers found that NDV-HXP-S conferred powerful protection in mice and hamsters.
“I can honestly say I can protect every hamster, every mouse in the world against SARS-CoV-2,” said Peter Palese, the leader of the research. “But the jury’s still out about what it does in humans.”