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OSU studies: Third booster provides strong protection against variants
KEITH ARNOLD
Special to the Legal News
Published: June 6, 2022
A pair of studies by Ohio State University researchers found that a third COVID-19 booster shot should provide strong and broad antibody protection against omicron variants.
The studies, the results of which were based on serum from human blood samples, tested neutralizing antibody levels against the BA.2 and BA.3 omicron variants and deltacron, a recombinant variant created by the exchange of genetic material between delta and omicron.
Results showed that a third mRNA vaccine dose was required to generate a high enough concentration of antibodies to neutralize BA.2 and deltacron, as well as other sublineage omicron variants, including the original, known as BA.1, and BA.1.1, a news release detailed.
“Three doses is better for everything,” said Shan-Lu Liu, senior author of both studies and a virology professor in the Department of Veterinary Biosciences at Ohio State.
The BA.2 variant constitutes about 90 percent of COVID-19 cases in the United States, according to recent national data.
“People have been asking about the recombinant deltacron and also BA.3, and now we have an answer. And it’s good news,” said Liu, who also serves as associate director of the university’s Center for Retrovirus Research and co-director of the Viruses and Emerging Pathogens Program in Ohio State’s Infectious Diseases Institute. “Based on the neutralization pattern, one booster shot can protect against BA.2 and deltacron, and we do not suspect that BA.3 will become predominant because it’s sensitive to neutralization by even two doses.”
In the study published in New England Journal of Medicine, researchers tested antibody levels in serum from 10 health-care professionals at Ohio State’s Wexner Medical Center.
After two vaccine doses, on average, antibody levels were 3.3-fold and 44.7-fold lower against BA.3 and deltacron, respectively, than those that neutralized the parent SARS-CoV-2 virus, the study found.
After the booster, antibody levels were much higher against all variants tested, and the same antibody level reductions were 2.9-fold and 13.3-fold––demonstrating a dramatic improvement in protection, particularly against deltacron, researchers said.
The study, next, examined blood samples from 18 patients in the hospital’s intensive care unit during the delta wave of the pandemic.
Researchers found comparable levels of antibodies against the parent virus and BA.3, but 137.8-fold lower concentrations against deltacron compared to the parent virus. Blood samples from 31 hospitalized non-ICU patients during the omicron surge showed much better antibody protection against deltacron.
A doctoral candidate in the university’s Molecular, Cellular and Developmental Biology Program, John Evans, described the spike protein of the deltacron variant as similarly structured to other omicron variants, suggesting that individuals infected with omicron seem to have pretty good protection against deltacron.
“However, compared to the booster, infection by omicron provides much less protection against deltacron,” said Evans, the first author of the studies.
The second study, which was published Cell Host & Microbe late last month, tested antibody levels in serum from 48 health-care professionals after their second mRNA vaccine dose and from 19 after their third mRNA vaccine doses, as well as 31 COVID-19 patients hospitalized during the omicron surge.
“For two vaccine doses, health-care workers had very weak neutralizing antibody concentrations against the omicron variants, but after the booster it evened out,” Evans said. “The neutralizing antibody levels were still lower against omicron compared to the parental virus, but much more comparable across variants and much higher. So, the booster provides much stronger protection and much broader protection.”
Patients with delta or omicron infection were similarly protected against their respective infectious variants, and a vaccine dose on top of infection improved protection, a summary of the study detailed. Among all of the health care professionals and infected patients studied, people who had received three vaccine doses had the broadest and strongest antibody protection overall.
The researchers conducted the cell-culture studies using pseudoviruses––a non-infectious viral core decorated with different SARS-CoV-2 spike proteins on the surface structured to match known mutations, the summary continued.
The method used to detect neutralizing antibodies in the blood samples accounted for the varying concentrations of antibodies produced by individuals.
Researchers have completed additional tests of neutralizing antibody responses to the omicron sublineages that are growing in dominance among newly reported cases.
The subsequent research has demonstrated that a booster provides sufficient antibody concentrations against the three additional omicron subvariants, though to a lower extent than protection seen for BA.1 and BA.2.
Also, previous omicron infection did not offer effective antibody protection against these variants, researchers said.
“The virus is evolving, which is typical for all RNA viruses, and what we have seen is not surprising at all,” Liu said. “Especially when we have lots of variants in the population, anything can happen, including recombination between them. That’s why we still need to be very cautious. The best preparation is to get the second booster.”
The work was supported by anonymous donor funds, grants from the National Institutes of Health, the National Center for Advancing Translational Sciences, the Glenn Barber Fellowship from Ohio State’s College of Veterinary Medicine, the National Cancer Institute and the Robert J. Anthony Fund for Cardiovascular Research. Liu also acknowledged the generosity of the health professionals and patients who participated in the studies.
Additional co-authors on both papers include Cong Zeng, Panke Qu and Yi-Min Zheng of the Center for Retrovirus Research; Linda Saif of Ohio State’s Center for Food Animal Health; and Claire Carlin, Joseph Bednash, Gerard Lozanski, Rama Mallampalli, Eugene Oltz, Peter Mohler and Richard Gumina of Ohio State’s College of Medicine.
Virus researchers Julia Faraone, Xue Zou and Kai Xu of Ohio State and Tongqing Zhou of the NIH were co-authors on the Cell Host & Microbe paper and the preprint.
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