SAN DIEGO (KGTV) -- An alarming new study outlines what it would take for the delta variant to fully escape antibodies from our existing vaccines: just four more mutations.
Two of the four mutations identified in the paper have already appeared in a very small number of patients infected with delta. There have been at least 36 recorded cases globally with two of these mutations, according to outbreak.info.
Researchers in Japan took the distinctive spike protein from the delta variant and made four changes to its amino acid structure. Three of these mutations are already found in the beta variant first discovered in South Africa: K417N, E484K and N501Y.
The scientists introduced this engineered virus, nicknamed Delta 4+, to immune cells extracted from vaccinated people. Antibodies produced by the existing Pfizer-BioNTech vaccine were unable to stop the man-made virus, the researchers reported.
The team concluded that delta is “poised to acquire complete resistance” to the current slate of authorized vaccines. However, three experts contacted by ABC 10News pushed back on the findings, saying that conclusion is premature. The paper has not yet been peer-reviewed.
“It's an interesting study, but one has to remember it's very artificial, right? It's a virus that they made. That's not out there,” said Dr. Nevan Krogan, a molecular biologist at the University of California, San Francisco.
A virus with all four of these mutations might never emerge in nature, experts said. Even if it did, it might not be as fearsome as it looks in lab experiments.
Sometimes mutations in one region of a virus weaken another region, said Dr. Davey Smith, a virologist and infectious disease expert at the University of California, San Diego.
“Even though it might work well in the lab doesn't necessarily mean that it works well in humans,” he said.
After similar lab experiments on the alpha variant, some scientists initially feared that a version with the E484K mutation would become the next dominant virus.
Sequences of such a variant did emerge multiple times, “but they didn’t end up causing any major outbreak clusters and died out,” wrote Karthik Gangavarapu, a Scripps Research computer scientist who helped build outbreak.info.
Experts also pointed out that the Japanese study only analyzed antibodies. Other immune cells induced by vaccination, like T cells, can help prevent minor infections from spiraling into severe disease. Research from the La Jolla Institute for Immunology suggests T cells are less susceptible to minor mutations than antibodies.
“I think these experiments are useful, but we really need to take them with a grain of salt,” Krogan said. “I don't think that these types of findings should ultimately scare the public.”
Vaccines remain effective against the delta variant, particularly the most severe outcomes. The Centers for Disease Control and Prevention released research this week showing the Pfizer vaccine was 93 percent effective against hospitalization from delta, although the overall efficacy against infection from the variant dropped to 53 percent four months after immunization.
The Japanese researchers behind the new paper said their findings have implications for vaccine booster shots. The U.S. has stockpiled at least 100 million booster shots and plans to begin rolling them out near the end of September. The shots are based on the blueprint of the original SARS-CoV-2 spike protein, not the delta variant.
With delta likely to gain new mutations “in the near future,” the researchers warned the virus could soon begin to evade these boosters. “Our data suggest that repeated immunization with the wild-type spike may not be effective in controlling the newly emerging Delta variants,” the researchers wrote.
The team showed that antibodies produced by an mRNA recipe updated for delta effectively blocked the engineered virus and the variant that’s largely circulating. They urged countries to consider a variant-specific booster approach.
Vaccine makers are already testing shots updated for the delta variant.
Pfizer previously announced that clinical trials on a delta-specific booster could begin in August. That means the first boosters rolling out next month will likely be the old recipes, not the new ones.
