Moderna aching for vaccine success


The FDA’s analysis of Moderna’s Covid-19 vaccine, released ahead of a panel review scheduled for Thursday, largely confirms the project’s safety and efficacy. While the overall efficacy of mRNA-1273 was pegged at 94.1%, when assessed at least two weeks after the second dose, this figure fell to 86.4% in people aged 65 and over. On safety, the most notable side-effect was Bell’s palsy, occurring three times in the vaccine group and once in the placebo group. One case in the vaccine group was considered serious: a 67-year-old woman with diabetes was hospitalised for stroke due to new facial paralysis 32 days after vaccination, though the situation ultimately resolved. Higher rates were also seen with BNT162b2, the rival mRNA vaccine from Pfizer and Biontech, however once again the FDA concluded that the number of cases was consistent with background rates, and that a causal relationship cannot be concluded at this time. As for other severe side-effects, both fatigue and muscle pain were seen in more than 10% of those given the Moderna vaccine, higher than the rates seen in the trial of BNT162b2. Still, this is unlikely to derail Moderna’s bid for approval, and indeed the FDA could give its blessing by the end of this week.

Pfizer/Biontech vs Moderna: selected severe adverse events
Severe or grade 3 adverse event* BNT162b2 (Pfizer/Biontech) dose 2 (%) mRNA-1273 (Moderna) dose 2 (%)
Fatigue 4.6 10.6
Myalgia 2.2 10.0
Arthralgia 1.0 5.8
Headache 3.2 5.0
Chills 2.1 1.5
*For Pfizer/Biontech, the briefing docs use "severe"; for Moderna, "Grade 3". Source: FDA.

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