Researchers around the world are currently working flat out on a vaccine that is specially tailored to the highly contagious variant of the coronavirus. However, early animal experiments show that the adapted vaccines may bring little additional benefit. The results have not yet been verified by experts. In addition, few animals were involved in most of the studies. Still, early evidence shows that a single dose of a custom-made Biontech/Pfizer-Moderna vaccine is unlikely to be of much use in the fight against Omicron.
Omicron has evolved into a dominant variant since its discovery in November 2021. This variant differs significantly from the original Sars-CoV-2 variant. This could explain why three doses of the existing vaccine against omicron provide less protection than, for example, against the alpha and delta variants.
Both Biontech/Pfizer and Moderna have announced that they have already started clinical trials with omicron-specific vaccines. Data should be available in the coming months. From April or May, Biontech could start delivering a corona vaccine tailored to Omikron. However, there are already animal studies that should shed more light on the benefits of the vaccines. In this study, three doses of vaccine were administered to the animals. These were two doses of the Moderna vaccine plus a booster dose of either the same vaccine or a matched vaccine.
In doing so, the authors found out that monkeys showed a broad antibody response against all variants in question (including omicron) when they were boosted with one of the two vaccines. The booster shots also have a positive effect on memory B cells.
Robert Seder, one of the study’s co-authors, spoke of a “very good thing”. So you can cover all known variants with a booster vaccination with the current vaccine. But the catch is that the study only looked at immune responses up to four weeks after the booster. It is therefore still completely unclear how long the increase in antibody production will last. The vaccinated animals in Seder’s group were also subsequently exposed to omicron viruses, with both boosters completely shutting down viral replications within two days, according to the study’s co-author.
According to Seder, a study with eight animals would not yet allow any definitive conclusions. However, given the compressed timescales in the pandemic, the findings are still valuable. In addition, a study was conducted with mice. This showed that a booster vaccine specific for Omicron is of no greater benefit than a normal booster vaccine. Overall, according to David Montefiori, director of the lab at Duke University, the studies would suggest that a one-time booster shot with an omicron-matched vaccine is probably not the answer. However, there are still important questions to be answered. Omicron studies by Pfizer and Moderna on humans should provide more information.