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1215 Moderna adcomm briefing
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Moderna’s COVID vaccine could sail through authorization even more smoothly than Pfizer-BioNTech’s

Dec 16, 2020 | 3:42 AM GMT

The few points of concern raised at the advisory committee meeting for Pfizer-BioNTech’s COVID-19 vaccine likely won't be issues for Moderna’s candidate.

Briefing documents released ahead of Thursday’s FDA advisory committee meeting to discuss Moderna’s mRNA-1273 reiterated the efficacy of the vaccine candidate, which was 94.1% across all age groups.

The agency stated that “the totality of available data are sufficient to support an evaluation of this product for EUA,” which could be issued by the end of the week.

The main point of contention at the Dec. 10 adcomm for BNT162b2 from Pfizer Inc. (NYSE:PFE) and BioNTech SE (NASDAQ:BNTX), which showed a similar level of efficacy to mRNA-1273 from Moderna Inc. (NASDAQ:MRNA), was the paucity of data in the youngest subjects for which the partners were seeking authorization, 16 and 17 year-olds. Concerns over giving the vaccine to adolescents prompted some committee members to vote against the vaccine’s authorization. The vaccine easily cleared the committee, however, in a 17-4 vote, with one abstention. 

mRNA-1273 has yet to be evaluated in adolescents, and Moderna is seeking EUA for people 18 and over, sidestepping the whole issue.

The briefing documents provided the first breakdown of the vaccine’s Phase III efficacy by age, showing protection against COVID-19 was 95.6% in participants ages 18-64, and fell to 86.4% in those 65 and older, although the efficacy rate in the over 65 population was based on a small number of confirmed cases — four in the vaccine group vs. 29 in placebo — and therefore preliminary. 

Across all age groups, there were 11 COVID-19 cases and zero severe COVID-19 cases in the vaccine group, and 185 COVID-19 cases, including 30 severe COVID-19 cases, in the placebo group, at a median follow-up of more than two months after the second dose.

Like BNT162b2 from Pfizer and BioNTech, which received emergency use authorization (EUA) on Dec. 11, Moderna’s mRNA-1273 showed efficacy after a single dose. “However, these data do not provide sufficient information about longer-term protection beyond 28 days after a single dose” and “the trial did not have a single-dose arm to make an adequate comparison,” noted FDA. 

Both vaccines have also demonstrated similar safety profiles, and both have shown imbalances in cases of Bell’s palsy, though FDA stated the “causal relationship is less certain because the number of cases was small and not more frequent than expected in the general population.” Moderna reported three cases of Bell’s palsy in the mRNA-1273 group and one case in the placebo group; Pfizer and BioNTech’s Phase III trials showed four cases of Bell’s palsy among vaccinated participants and zero cases in those who received placebo. 

Another group that lacks mRNA-1273 safety and efficacy data is pregnant women, although Moderna performed a reproductive toxicity study of mRNA-1273 in rats which was submitted to FDA on Dec. 4. FDA concluded that mRNA-1273 given before mating and during gestation periods did not have any adverse effects on female reproduction, embryonic development or postnatal development except for skeletal variations which are common and typically resolve postnatally without intervention.

Whether vaccination prevents asymptomatic infection or spread remain open questions. 

In an addendum to Tuesday’s briefing documents, Moderna showed that mRNA-1273 may prevent asymptomatic infection. The company collected nasopharyngeal swabs ahead of both vaccine doses to detect SARS-CoV-2. Among baseline negative participants, 14 (0.1%) in the vaccine group and 38 (0.3%) in the placebo group were SARS-CoV-2-positive at the second dose without evidence of COVID-19 symptoms.

If mRNA-1273 receives an EUA, Moderna said it may amend its vaccine protocol to reconsent participants who received placebo to be offered mRNA-1273 and to remain in the trial, which would enable the company to collect further safety and efficacy data for a follow-up period of two years.

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