Earlier this month, the CDC endorsed using the updated COVID-19 booster shots. The updated COVID booster shots were specifically tailored to fight against the two most prevalent omicron subvariants, BA.4 and BA.5. Their decision came a day after the FDA’s emergency use authorization of the shots. The agency’s backing enables a full roll-out of the updated vaccines within days. Moderna and Pfizer both have an updated COVID booster. The shot comes with more than 450 people dying from COVID-19 every day in the U.S.
As of August 31, 2022, only 48.5% of people eligible received their first booster shot. Under 34% of those eligible received their second. One reason these numbers are low is that people could’ve possibly been waiting on the updated booster. However, people should understand that booster shots proved an essential layer of protection against COVID-19.
What Are The Differences Between Updated COVID Booster?
The newly authorized shots are the first updates to the original COVID-19 vaccines, which were introduced in late 2020. They used the same mRNA technology as the original vaccines. The new “bivalent” version consists of mRNA that encodes the spike proteins of both the SARS-CoV-2 virus and the more recent omicron subvariants, BA.4 and BA.5.
As of last month, the BA.4 and BA.5 omicron subvariants are dominant worldwide. In the U.S., 89% of COVID-19 infections are caused by BA.5, and 11% are caused by BA.4.The inability of the original vaccine strains to prevent reinfection and trigger long-term protective immunity prompted the need for the reformulated vaccines.
How Protective Are The New Shots Against Infection?
Currently, there aren’t human studies on the efficacy of the new bivalent vaccine at preventing reinfections and providing long-term immune protection. But in human clinical trials and laboratory studies, Pfizer and Moderna found that their initial version of the new vaccine induced a robust immune response and extended protection against the original strain and the BA.1 variant. Furthermore, the companies reported that the same early combination generated a significant antibody response against the newest omicron subvariants, BA.4 and BA.5. However, this antibody response was lower than that seen against subvariant BA.1.
Based on those results, the FDA rejected the BA.1 bivalent boosters. The agency believed the boosters would’ve fallen short of providing enough protection against the newest strains. Therefore, the FDA asked Pfizer and Moderna to develop bivalent vaccines targeting BA.4 and BA.5 instead of BA.1.
Since clinical trials are time-consuming, the FDA considered animal studies and other laboratory findings. Unfortunately, that decision has riled up controversy on whether it was appropriate for the agency to approve a booster without direct human data to support it. The FDA stated that millions have safely received the mRNA vaccines, and the changes in the mRNA sequences in the vaccines do not affect vaccine safety. Thus, the bivalent vaccines were deemed safe, and there’s no need to wait for human clinical trials.
Lastly, many wonder how the bivalent vaccines will work against future variants. The new shot will provide excellent protection if it is a minor mutation or set of mutations compared to the original strain or the BA.4 and BA.5 variants. Sadly, if the new strain were to possess highly unique mutations in its spike protein, then it’s likely that it could dodge immune protection.
