Bivalent COVID Vaccines
The bivalent boosters (with half BA.4/BA.5 and half ancestral variant) were designed to produce antibodies and immune memory to Omicron, and have demonstrated pan-Omicron efficacy as shown in studies just released over the last few days.
Keep in mind that Pfizer and Moderna had already performed human trials in a bivalent booster with BA.1, which demonstrated both safety and efficacy. The US government asked them to reformulate the vaccine to the current variant, which is now BA.5, and frankly we’re lucky that we haven’t had a different predominant variant arise during that time. Given that, these are incredibly timely.
Pfizer and Moderna were able to spin up Ba.4/BA.5 bivalent boosters in those 2 months because the FDA recognized that the human trials had already been performed for BA.1, and that then making them re-run the same trials which had already demonstrated safety and efficacy with just a slight change in one variant of the bivalent formulation would waste valuable time. So the subsequent studies were performed in mice simply to demonstrate the efficacy of inducing an adequate immune response. This…
