A debate about the need for additional COVID-19 vaccine doses is heating up ahead of Friday's U.S. Food and Drug Administration (FDA) vaccine advisory meeting, which is slated to discuss the need for an additional Pfizer (PFE)/BioNTech (BNTX) shot.
Both the FDA and Pfizer released documents Wednesday detailing the data and information being weighed by the advisory panel. Pfizer has been keen on additional doses, or boosters, in light of data from Israel — with which the company has a close partnership — showing waning efficacy of the vaccine.
"The high neutralizing titers against the Beta and Delta variants after a third dose ... are encouraging. These data suggest that a third dose could re-establish the efficacy levels shown 1 month after two doses, prolong duration of protection, and further increase the breadth of protection," Pfizer said.
Meanwhile, the FDA, in its briefing document, said that it did see convincing protection from a third dose, but it has not "independently reviewed or verified the underlying data or their conclusions."
Even so, the data will be discussed at the September 17 meeting, as the U.S. lacks data relevant to its population.
"It should be recognized that while observational studies can enable understanding of real-world effectiveness, there are known and unknown biases that can affect their reliability. Due to these biases some studies may be more reliable than others," the FDA said.
The cautious tone matches what two of the top vaccine officials at the FDA, both of whom are departing, wrote in collaboration with World Health Organization (WHO) officials and others in a recent Lancet article.
There, the authors wrote that there does not appear to be enough evidence to "show a need for boosting in the general population, in which efficacy against severe disease remains high."
Meanwhile, Moderna (MRNA) announced new data Wednesday that suggests a lower risk of breakthrough infection 8 months after the first dose compared to 13 months after the first dose. The data is not yet peer-reviewed, but has been submitted, the company said.
The timeline matches the Biden administration's initial announcement of targeting 8 months after the initial course starting September 20.
By comparison, Pfizer's study supports 6-8 months after the initial course. The company remains the only one with a fully approved vaccine for ages 16 and up, as well as authorization for adolescents.
Moderna has yet to receive authorization for the latter, despite submitting in the summer, and it has completed its submission for full approval. It has also provided data supporting a half dose, 50 micrograms compared to the original 100 micrograms, for its booster shot.
President Stephen Hoge told Yahoo Finance Wednesday that the timeline for 5- to 11-year-olds will follow a similar timeline to that of Pfizer, which recently announced and end-of-month completion of the trial and filing for approval in October.
Whether or not a booster, or additional dose, will be needed continues to be a controversial topic in the health and science community. Some experts believe it is better to be safe than sorry, while others believe the proper memory function that the body holds to fight an infection after learning from the vaccines is sufficient.
"This is the key scientific question we're all wrestling with now," Hoge said.
"We don't really know" if annual boosters or a final third shot will provide the best protection, Hoge added.
There is also a split in the community over whether or not protection against severe disease should be the ultimate goal, rather than protection against any infection — which is currently the case with breakthroughs and could lead to further spread. There is also a split over whether an additional dose means the full protective course of a COVID-19 mRNA shot will have to be a three-dose course or if the additional shot is indeed a booster.
The bottom line remains, however, that despite the current Delta surge, and general concerns about variants, "these variants have not yet evolved to the point at which they are likely to escape the memory immune responses induced by those vaccines," according to the Lancet article authors.
And, they added, ensuring the entire global population completes its first round of shots is more important at this time.
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