Moderna’s omicron booster was only as good as current vaccine in monkey study

Extreme close-up photo of a gloved hand holding a small bottle.
expansion / / Vials of the current Moderna COVID-19 vaccine.

In a small group of monkeys, the Omicron-specific version of Moderna’s COVID-19 vaccine did not provide better protection against Omicron variants than Moderna’s current highly effective boosters. This finding raises the question of whether it is necessary to switch to mutant-specific doses.

the study Led by researchers at the National Institutes of Health, it was posted to the preprint server last Friday. This study has not been peer-reviewed or published in scientific journals. Also, there are all restrictions on animal testing, and only 8 monkeys are involved. The results of this study need to be validated in ongoing human trials.

Still, there are good reasons to believe that the findings will be maintained. As the authors of the research notes point out, this is not a booster specific to Moderna’s first variant. The company had previously developed a booster for the variant beta of concern. Like the Omicron-specific boosters, beta boosters did not outperform the original vaccine in protecting primates from beta. And that discovery was later withstood in human clinical trials.

“The non-human primate (NHP) model has largely predicted what was observed in humans in terms of protective effects,” the author writes.

Moreover, this finding is consistent with the concept of “antigenic sin” (also known as antigenic sin). This idea suggests that if the immune system is presented with a pathogen similar to that previously fought, the encounter activates immunological memory from previous interactions. In other words, a response to an omicron-specific vaccine builds a response to an earlier version of SARS-CoV-2 encountered.

That’s exactly what vaccine researchers saw in their new monkey research. After researchers gave all eight monkeys two standard doses of Moderna’s vaccine, humans boosted four monkeys with the current booster and the other four with a booster specific to Omicron. Both boosters activated specific immune cells called memory B cells that are cross-reactive. This means that the cells targeted both older versions of SARS-CoV-2 and Omicron. More specifically, 70% to 80% of Memory B cells were bispecific to the old virus and Omicron, regardless of which booster the monkey received. Also, while current boosters spurred responses specific only to older viruses, Omicron boosters did not appear to have spurred responses specific to Omicron-specific B cells.

Equally good

Otherwise, boosting the monkeys with either vaccine resulted in a similarly strong increase in neutralizing antibodies to Omicron. And when vaccinated and boosted monkeys challenged Omicron infection, both boosters protected primates equally well from lower respiratory tract disease.

“Therefore, Omicron boosts may not provide greater immunity or protection compared to current boosts. [Moderna] Vaccine “.

For clarity, that’s not necessarily a bad thing. Today’s boosters offer strong protection against Omicron. Up-to-date real-world data reported by the Centers for Disease Control and Prevention Boosters have been found to be 82% effective in preventing the need for emergency or emergency treatment with COVID-19 and 90% effective in preventing hospitalization with COVID-19. Vaccinated and boosted people are one-fifth more likely to be infected with COVID-19 in the Omicron wave than unvaccinated people.

Nonetheless, Moderna is currently conducting clinical trials at Omicron-specific booster doses to try to exceed these numbers. The company said it expects to distribute boosters later this year, perhaps in case of a surge in cold weather. Vaccine maker Pfizer and its partner BioNTech are also working on Omicron-specific vaccines that have entered clinical trials.

It is unclear if new monkey data will upset those plans. The authors suggest that if the findings are tolerated by humans, there would be no need or benefit to switch to Omicron-specific boosters for now. And even though Omicron remains the major circulating variant, the author recommends replacing the current vaccine with Omicron-specific shots, especially for currently unvaccinated children and babies. Claims that more data is needed. For example, mouse data suggest that omicron-specific vaccines may not provide the same cross-reactive protection against other mutants. If that is the case for humans, a combination vaccine that targets multiple mutants at once may be appropriate. Overall, the authors argue that variant-specific boosters may only be needed if future variants evolve that can dodge the current cross-reactive response.

Correction: This story has been updated to correct the potential for Omicron infection in vaccinated and boosted people compared to unvaccinated people. They are one-fifth chance instead of fourteen.

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