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The race for a Covid-19 vaccine slowed on Tuesday, as both U.S. regulators and the head of the Trump administration’s Operation Warp Speed initiative tapped ever so softly on the brakes.

The Food and Drug Administration released strengthened rules for authorizing any Covid-19 vaccine on an emergency basis. And Moncef Slaoui, co-chair of Operation Warp Speed, revealed that the government’s vaccine fast-tracking effort has urged manufacturers not to apply for emergency use authorization until they have significant amounts of vaccines to deploy.

That could push back even the first such authorization — expected to be for a vaccine being made by Pfizer and BioNTech, if it proves to be effective — into sometime in mid- to late November.


“The one learning message that we came to … was to recommend to the companies that we are supporting that if they achieve efficacy demonstration [of their vaccine] while there are no vaccine doses available at industrial scale … to be able to immunize at least a relevant fraction of the population, that they should refrain or at least consider refraining for filing for an EUA,” Slaoui said during a Covid-19 vaccines symposium on Tuesday.

Approval of a vaccine that wasn’t actually available to use would be “a major disappointment” to the public, Slaoui said.


There has been deep concern in the public health world that President Trump would seek to force the FDA to approve Covid-19 vaccines before Election Day — and before large clinical trials currently underway to determine safety and efficacy have reached statistically significant conclusions. Polls suggest many Americans are wary of the vaccines being produced through Operation Warp Speed, and public health experts fear political interference in the approval process would further undermine public confidence.

The FDA has been attempting to strengthen the rules by which it would agree to issue an emergency use authorization, or EUA, for Covid-19 vaccines, but had been stymied by the White House. On Tuesday, the regulatory agency released the updated safety standards amid a number of guidance documents it posted online in advance of an important meeting on Oct. 22 of the vaccines and related biological products advisory committee, which advises the FDA on vaccine approvals.

According to the revised rules, the FDA wants vaccine manufacturers to collect safety data on at least half of their clinical trial subjects for two months after they have received their second dose of vaccine, if the candidate vaccine is a two-dose vaccine. (Of the current frontrunners in the vaccine race, only the Johnson & Johnson vaccine, which only recently began its Phase 3 trial, uses a one-dose regimen.)

Pfizer and BioNTech are viewed as most likely to deliver an early answer from trials of their vaccine, which uses a new technology called mRNA to mount an immune response to the virus. But at Pfizer’s virtual investor day on Sept. 15, the company said that 12,000 of its then-planned 30,000 volunteers had received a second dose — meaning that Pfizer and BioNTech would not have enough data to apply for an EUA until mid-November at the earliest.

Pfizer and BioNTech have since said they would expand their study to include 44,000 patients. It’s not clear whether the FDA would want two months of data on half the patients on the larger number, or the original 30,000.

Slaoui also stressed Tuesday that he expected the first efficacy data from Covid-19 vaccines to become available in November or December.

Peter Marks, the FDA’s top vaccine regulator, insisted Tuesday that the two-month follow-up timeline was guided by data showing that the majority of adverse events occur roughly within two to three months after vaccine administration.

“There’s something that’s really amazing that you can actually use sometimes … you can sometimes actually use data,” Marks said during the symposium, staged by Johns Hopkins University and the University of Washington. “We picked two months as something that was reasonably aggressive yet also somewhat kind of in the middle — not too aggressive, not too conservative.”

Former FDA Commissioner Scott Gottlieb groused during the event over how much “political dust” was kicked up by political officials over the FDA’s guidance, for, he said, little gain. Gottlieb, who served in the Trump administration from 2017 to 2019 and now serves on the board of Pfizer, appeared to be referencing reporting that White House officials were blocking release of the FDA’s guidance, although he did not name specific officials nor specific media reports in his comments.

In addition to the Pfizer-BioNTech vaccine, an mRNA vaccine being produced by Cambridge, Mass.-based Moderna, is expected to have data within that time frame.

Slaoui told the symposium that though mRNA vaccines have never before been approved, both Moderna and Pfizer-BioNTech are now able to produce vaccine at industrial scale.

“We are in the process of stockpiling doses in the single-digit million doses in the months of October … and then in the tens of millions of doses in November,” Slaoui said.

Nicholas Florko contributed reporting.


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