By Athena Xue
Following the global and local emergence of COVID-19 variants, Stanford researchers predict that the Pfizer and Moderna vaccines will continue to be mostly effective in the near future, though each of the new strains responds differently to the current vaccines.
Multiple variants have been identified to date, but the most concerning ones are the B.1.1.7 strain discovered in the United Kingdom, B.1.351 in South Africa and P.1 in Brazil –– all of which have already reached the United States. Recently, the new L452R strain identified in Denmark caused outbreaks in Santa Clara County.
While the B.1.1.7 variant is “fully susceptible to vaccine-induced immunity,” B.1.351 is less susceptible but “still within the range where we expect some protection,” associate medicine professor Catherine Blish wrote in an email to The Daily.
According to infectious disease clinical professor Stanley Deresinski, the Moderna vaccine has a six- to nine-fold reduced potency on the B.1.351 variant but no loss in potency for B.1.1.7. The vaccine efficacy rates for the other variants have yet to be reported.
However, researchers said that even if new mutations do render the current vaccines ineffective, they can easily be updated to block against new strains. Moderna has already initiated its Phase I testing for a vaccine booster dose against B.1.351, according to Blish and Deresinski.
“One of the values of mRNA vaccines is that new ones can be produced in the laboratory within weeks,” Deresinski wrote in a statement to The Daily. “Jennifer Haller received the first dose of the Moderna vaccine 66 days after scientists in the U.S. were able to view the published genetic code of SARS-CoV-2.”
Infectious disease clinical professor Jake Scott referred to the mRNA vaccines as “nimble” and strong to begin with. This offers some “wiggle room” –– even if the vaccines were six-fold less active, they would still potentially be effective, he said.
Next in line for approval are the Johnson & Johnson and Novavax vaccines, but recent testing indicated that they experience reduced efficacy against the B.1.351 strain from South Africa, according to sixth-year chemistry Ph.D. student Payton Weidenbacher. Weidenbacher is currently working in biochemistry professor Peter Kim’s lab to develop a nanoparticle vaccine that can be kept at less extreme temperatures.
While the Johnson & Johnson vaccine demonstrated a 72% efficacy rate in the U.S. but only a 57% rate in South Africa, it still offers complete protection against severe disease and death for those who are infected, Weidenbacher said.
Shifting the direction of vaccine research
The mutating SARS-CoV-2 virus is not an unexpected development but rather a completely normal progression of the disease, Blish wrote. Many vaccine developers have anticipated the emergence of variants and have already been tackling it in their research, she added.
Associate biochemistry professor Rhiju Das leads the OpenVaccine challenge at Stanford, working to design a “highly stabilized” mRNA vaccine that could allow the “deployment of mRNA vaccines without freezing.”
Das said that he and his lab have now started addressing the new variants, figuring out how to “rapidly redesign” the mRNA sequences in their vaccines to code for the emerging strains.”
“The real worry, though, is that more variants will arise that will completely escape the vaccines,” Das said. “Once they see the medicines we’re deploying, the viruses will be under pressure to evolve resistance.”
Meanwhile, in the Kim Lab, Weidenbacher and his colleagues have started investigating the major new strains for their nanoparticle vaccine.
“The big question that we’re grappling with is: what is the best variant to immunize?” Weidenbacher said.
To answer this question, the lab is pinpointing the mutations that the variants have in common, which are likely the ones that have an evolutionary advantage and will continue to be found in future strains.
“If three independent occurrences around the world have all elicited the same sets of mutations, it seems like those mutations are relevant to include in a new vaccine,” Weidenbacher explained.
Looking forward, Weidenbacher said that “people don’t know if this virus is going to keep on mutating” like the flu, or if it will “hit some sort of plateau” and converge into a single strain.
High mutational frequency is the reason why we need new flu vaccines every year and have not yet developed a vaccine for human immunodeficiency virus (HIV), Blish said. However, she believes it’s “unlikely that we will require yearly vaccines because coronaviruses simply don’t mutate as quickly as influenza.”
According to Deresinski, the typical SARS-CoV-2 virus mutates at a rate about half that of influenza and a quarter that of HIV.
“The news about these new variants coincided with the rollout of these incredibly effective vaccines, so it’s basically a kick in the butt to really do everything we can to vaccinate as many people as possible,” Scott said.