In a study published on the pre-print server bioRxiv, Pfizer and BioNTech have shown their COVID-19 vaccine appears to be effective against a key mutation in the new strains of the coronavirus discovered in the UK and South Africa. What’s more, Pfizer scientists say their vaccine not only protects against these two variants, but 14 other coronavirus strains, as well.
The highly transmissible variants from the UK and South Africa are different, but they both have multiple mutations in their spike, or S, proteins. Specifically, they share the N501Y mutation, which is located in the receptor-binding site of the spike protein and results in the virus’s spike protein binding more tightly to its receptor. Spike proteins are the key targets of virus-neutralizing antibodies in the vaccines currently approved for Emergency Use Authorization in the United States, including Pfizer and BioNTech’s BNT162b2.
To test the effectiveness of the vaccine against the new strains, scientists from Pfizer and the University of Texas Medical Branch used blood samples from 20 participants of the pharmaceutical manufacturer’s Phase 3 trial that had already received both doses of the vaccine. The antibodies in the patients’ blood were able to neutralize SARS-CoV-2 with the N501Y mutation just as well as they neutralized the virus without the mutation.
Although the study was performed in vitro and has not yet been peer-reviewed, it does offer a slight sigh of relief. However, as Pfizer scientist Phil Dormitzer points out, there is still work to be done.
“We've now tested 16 different mutations, and none of them have really had any significant impact. That's the good news," Phil Dormitzer, a scientist at Pfizer, told Business Insider. "That doesn't mean that the 17th won't."
The mutated virus substitute created in the University of Texas Medical Branch’s lab for the experiment did not include the full set of mutations in either the UK or South Africa strains, leaving the door open to further questions about both the vaccine’s effectiveness and the mutations.
“Further data are needed to monitor the Pfizer-BioNTech COVID-19 vaccine’s effectiveness in preventing COVID-19 caused by new virus variants,” the pharmaceutical company said in a statement on Friday. “If the virus mutates such that an update to the vaccine is required to continue to confer protection against COVID-19, we believe that the flexibility of BioNTech’s proprietary mRNA vaccine platform is well suited to enable an adjustment to the vaccine.”
Moderna—the biotech company behind the only other approved COVID-19 vaccine in the U.S.—has not released the results of any studies regarding their vaccine and the new variants, but they did say in late December that they expected the vaccine-immunity provided by their vaccine to carry over to the UK strain.
“The full-length Spike protein is 1,273 amino acids long, so while recent variants involve multiple mutations, for instance up to 8 amino acid changes in the spike protein of the B1.1.7 strain, these represent less than a 1% difference from the spike protein encoded by Moderna’s vaccine,” Moderna said in a statement. “While we plan to run tests to confirm the activity of the vaccine against any strain, the broad range of potential neutralizing antibodies made possible by the Moderna COVID-19 vaccine provides confidence that our vaccine will also be effective at inducing neutralizing antibodies against them.”
In the UK, AstraZeneca and Oxford University’s vaccine has been approved for distribution. Like Moderna, the pharmaceutical company intends to test their vaccine against the new strains, but has said it fully expects the approved vaccine to be effective against both the UK and South African mutating variants.
Photo: B cells release antibodies to bind to the virus. Credit: AstraZeneca