On Friday, Pfizer has submitted a briefing document to the FDA’s Vaccines and Related Biological Products Advisory Committee. The maker of the popular mRNA vaccine stated based on studies, that its product loses nearly half of its efficacy against the notorious Delta Variant of coronavirus in just a few months’ time.
Despite Pfizer’s recommendation to introduce the third booster shot for its coronavirus vaccine, the call seems to have fallen on deaf ears with the US regulator, with its panel voting overwhelmingly against such practice citing lack of safety data ( and leaving the pharma giant in a difficult situation.
Pfizer’s report mentions a recent study by Southern California Kaiser Permanente Medical Group, which evaluated the overall and variant-specific effectiveness of the Pfizer-BioNTech’s COMINARTY vaccine against SARS-CoV-2 infections and COVID-19-related hospitalizations by time since vaccination.
The researchers used data collected all over the US between 14 December 2020 and 8 August 2021, making it possible to explore both the Delta variant and other strains of the novel coronavirus.
Key findings demonstrate that the efficacy of Pfizer against Delta was high during the first month after the jab, but it declined dramatically (from 93% to 53%) within 4 months after full vaccination.
Figure 1. Adjusted VE Against SARS-CoV-2 Infections: KPSC Members ≥12 Years of Age
© Photo : The Kaiser Permanente Southern California (KPSC)
Keiser Permanente’s researchers have also concluded that Pfizer’s protection against hospitalization lasts “through roughly six months”, and that “reductions in effectiveness against SARS-CoV-2 infections over time are likely primarily due to waning rather than Delta escaping vaccine protection.”
According to the report submitted with the FDA, Pfizer’s strategy at the moment is to administer booster doses of its vaccine approximately every 6 months. These recommendations were made based on the findings from post hoc analysis of cases by time since vaccination, and it seems to be the only solution offered by Pfizer at the moment.
Despite the fact that the efficacy of its vaccine is waning so quickly, Pfizer has failed to convince the US regulator to introduce booster shots. Nevertheless, it’s unclear whether the pharmaceutical giant will get the same responses from governments in other countries, such as Australia, Canada, or New Zealand.
The countries that appeared to have some of the earliest and successful vaccination campaigns earlier this year and that heavily relied on the Pfizer vaccine– including the US itself – are now going through a major spike in infections again. Israel in particular, where over 60% were fully vaccinated with Pfizer, was supposed to become the poster example of that vaccine’s effectiveness, yet is experiencing a new wave of COVID.
This is not the only problem, which Pfizer faced in recent months. A preprint Mayo Clinic study has concluded that Pfizer’s efficacy against Delta strain of coronavirus has fallen from 76% to 42%. But despite its jab’s sub-par performance, Pfizer BioNTech had secured contracts for 2.1 billion doses worldwide by July of 2021, with the potential 3 billion doses by the end of the year.