One month after regulators in the United States and United Kingdom froze trials of a British novel coronavirus vaccine candidate, U.S. testing is still on hold.
That has big implications for the urgent, multi-billion-dollar effort to produce a safe, effective COVID-19 vaccine. The testing pause could slow development efforts by Astrazeneca, the U.K. pharmaceutical company, and, in turn, leave two rival pharmaceutical giants alone as leading developers of coronavirus vaccines. The problem? Both of those firms are developing the same basic type of high-tech—and potentially risky—messenger-RNA vaccine, one that has never been successfully rolled out in modern medicine..
Welcome to Rabbit Hole, where we dive deep on the biggest story. It’s for Beast Inside members only. Join up today.
ADVERTISEMENT
“We do not want all our eggs in one basket,” Jeffrey Klausner, a professor of medicine and public health at UCLA who previously worked at the U.S. Centers for Disease Control and Preventions, told The Daily Beast.
AstraZeneca is developing its vaccine, known as “AZD1222,” along with Oxford University. It’s just one of six vaccine candidates that have received major funding from Operation Warp Speed, the U.S. government’s $13-billion vaccine-accelerator. AstraZeneca did not respond to a request for comment for this story.
But the vaccine showed promise, beginning large-scale, Phase 3 trials in late August and aiming to enroll 30,000 people in the U.S. along with around 10,000 others in the U.K.
Enrollment and testing were still in their early stages when a female test subject in the U.K. came down with transverse myelitis, a kind of spinal-cord inflammation.
On Sept. 6, a British safety board ordered a halt to AstraZeneca’s U.K. vaccine work. A similar board in the U.S. quickly ordered its own safety freeze. Starting on Sept. 6, the company stopped enrolling new test subjects and also stopped administering doses to the people it had already enrolled.
The sick test subject recovered, however, and trials quickly resumed in the U.K., Brazil, India, and South Africa. But testing remains on hold in the U.S. as investigators try to determine for sure whether the illness was related to the vaccine.
So far, around 18,000 people worldwide have received at least one dose of AZD1222. But like many other coronavirus vaccine-candidates, the vaccine could require two doses to be most effective. AstraZeneca’s testing plan administers doses four weeks apart. The timing of the U.S. testing halt means that American test subjects have received just one dose, at most.
And the total number of Americans in AstraZeneca’s trials may be just a fraction of the 30,000 the company hoped to enroll; the company hasn’t released the exact figures. In any event, that number can’t grow until the U.S. safety board, made up of independent scientists, gives AstraZeneca the all-clear.
The pause in U.S. enrollment will delay completion of Phase 3 trials, Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, told The Daily Beast. And while the FDA in theory could approve AZD1222 for use in the U.S. after seeing trial results from other countries, the agency is unlikely to do so, he explained.
“The FDA prefers to have data on Americans before licensing a vaccine for Americans,” Offit said.
The FDA did not respond to a request for comment for this story. But it’s worth noting that the agency recently strengthened its rules for authorizing any vaccine candidate for early emergency use, apparently signalling firm resolve in the agency to fully test new vaccines before rushing them out to the public, the politics be damned.
What’s most discouraging to the experts The Daily Beast spoke to is the shrinking diversity among the leading vaccine candidates—and the implications of that trend for the speedy, efficient distribution of doses.
AZD1222 is an inactivated-virus vaccine, meaning it contains harmless copies of the SARS-CoV-2, or novel coronavirus, pathogen. The idea is that the inactivate virus should encourage an immune response that protects against active coronavirus.
By contrast, the two major vaccine candidates that are now farthest along in Phase 3 trials—Pfizer and Moderna’s–are both mRNA vaccines that include genetically engineered nanoparticles that encourage the production of coronavirus-fighting antibodies.
There’s never been an mRNA vaccine before. The technology is brand new and the vaccines that could result will almost certainly require special handling. “These RNA vaccines are very unstable and require deep freezing, unlike the other platforms,” Surinder Singh, a vice president at Japan-based pharma Otsuka Pharmaceutical, told The Daily Beast.
There have been plenty of inactivated-virus vaccines over the years, however. Otto Yang, an expert in infectious diseases at UCLA, described them as “simple, older technologies.” At most, they require refrigeration, not freezing, making them cheaper and easier to distribute.
AstraZeneca’s testing pause could mean that one of the costlier and more delicate mRNA vaccines beats AZD1222 to market in the U.S., possibly as soon as early next year.
Dmitry Korkin, a bioinformatics researcher at the Worcester Polytechnic Institute in Massachusetts, told The Daily Beast he’d prefer AZD1222 or something similar in the candidate that ultimately gets to consumers. “I would rather have an old but proven technology with low risk,” he said.
But U.S. regulators have held firm. As long as there’s a chance AstraZeneca’s vaccine made a test subject sick, it’s best to hold back on the low-tech vaccine. Even if that means a riskier vaccine technology overtakes it.
