Come Sat­ur­day, the US will like­ly have two Covid-19 vac­cines.

The FDA’s ad­vi­so­ry com­mit­tee on vac­cines vot­ed unan­i­mous­ly Thurs­day — with one ab­sten­tion — to rec­om­mend an emer­gency use au­tho­riza­tion for Mod­er­na’s mR­NA-based Covid-19 shot, set­ting the agency up to like­ly is­sue the EUA on Fri­day. The agency does not have to lis­ten to the com­mit­tee but usu­al­ly does.

“The ev­i­dence that has been stud­ied in great de­tail on this vac­cine high­ly out­weighs any is­sues that we’ve seen,” Stan­ford in­fec­tious dis­ease pe­di­a­tri­cian Hay­ley Gans said. “And I think re­al­ly sup­ports us be­ing able, with the pan­dem­ic, move for­ward and fi­nal­ly pro­vide a safe and ef­fec­tive way of get­ting to herd im­mu­ni­ty.”

The unan­i­mous vote con­trast­ed with last week’s ad­vi­so­ry hear­ing on Pfiz­er-BioN­Tech’s own mR­NA shot, where four com­mit­tee mem­bers vot­ed against the ques­tion put to them and one ab­stained. But the dis­crep­an­cy may come down to a mi­nor dif­fer­ence be­tween the two ap­pli­ca­tions.

Pfiz­er asked for an EUA to vac­ci­nate any­one 16 years of age or old­er, but some mem­bers of the com­mit­tee were con­cerned that Pfiz­er did not con­duct suf­fi­cient test­ing on 16 and 17 year olds and vot­ed ac­cord­ing­ly, even though they sup­port­ed vac­ci­nat­ing any­one over 18. Mod­er­na on­ly re­quest­ed an EUA for peo­ple 18 and up, as­suag­ing the com­mit­tee’s con­cerns.

Nev­er­the­less, some ad­vi­so­ry mem­bers still sparred with the FDA over the word­ing of the ques­tion put be­fore the com­mit­tee, fear­ing that the word­ing may mis­lead the pub­lic in­to be­liev­ing that the vac­cine has been ful­ly ap­proved. They of­fered adding “ex­per­i­men­tal” or “emer­gency use au­tho­riza­tion” to the ques­tion.

“This can be in­ter­pret­ed as rec­om­mend­ing full ap­proval,” said NCAT’s Michael Kuril­la. “That may… pre­clude not on­ly ad­e­quate eval­u­a­tion of this vac­cine but al­so fu­ture and on­go­ing Covid vac­cines in de­vel­op­ment.

FDA of­fi­cials and oth­er mem­bers, how­ev­er, quick­ly shot down the idea.

“The ques­tion is nev­er when do you know every­thing, it’s when do you know enough,” said Paul Of­fit, an in­fec­tious dis­ease physi­cian at Chil­dren’s Hos­pi­tal of Philadel­phia.

Kuril­la ab­stained over the word­ing, as well as con­cerns that an ex­pand­ed ac­cess pro­to­col may have been more ap­pro­pri­ate than an EUA, al­low­ing tri­als to con­tin­ue to col­lect ran­dom­ized da­ta.

An EUA for Mod­er­na would rough­ly dou­ble the amount of vac­cine im­me­di­ate­ly avail­able in the U.S., from over 20 mil­lion dos­es to over 40 mil­lion dos­es. The vac­cine is al­so eas­i­er to dis­trib­ute as it can be han­dled at the same tem­per­a­ture as most ap­proved vac­cines — un­like Pfiz­er’s shot — and the U.S. has ex­er­cised op­tions to ac­quire 200 mil­lion dos­es through June.

While prof­fer­ing dozens of ques­tions, the com­mit­tee nev­er ex­pressed se­ri­ous con­cerns about the safe­ty or ef­fec­tive­ness of the vac­cine. Mod­er­na an­nounced pre­vi­ous­ly that the vac­cine was 94.1% ef­fec­tive at pre­vent­ing symp­to­matic Covid-19. Al­though the FDA re­view re­vealed that the vac­cine ap­peared less ef­fec­tive in vol­un­teers over 65 — 86.5% pro­tec­tion — com­pa­ny ex­ec­u­tives not­ed that the dif­fer­ence was not sta­tis­ti­cal­ly sig­nif­i­cant.

In­stead, dis­cus­sion cen­tered on rare po­ten­tial side ef­fects and Mod­er­na’s plan for what to do with ad­verse events. The FDA’s re­view turned up one sur­pris­ing se­ri­ous event: Two vol­un­teers who had pre­vi­ous­ly re­ceived a der­mal fill­ing ex­pe­ri­enced fa­cial swelling af­ter re­ceiv­ing the vac­cine.

The pan­el asked re­peat­ed­ly the al­ler­gic re­ac­tions that have emerged in the two weeks since Pfiz­er’s vac­cine was in­oc­u­lat­ed. Al­though Mod­er­na said they did not see any cas­es of ana­phy­lax­is in their study — out­side of one al­ler­gic re­ac­tion two months out, from some­one with a soy al­ler­gy — they al­so not­ed it as one po­ten­tial se­ri­ous event to mon­i­tor long term.

Still, Mod­er­na CMO Tal Zaks cau­tioned that each com­po­nent of the com­pa­ny’s lipid nanopar­ti­cle, which may have trig­gered the al­ler­gic re­ac­tion in Pfiz­er re­cip­i­ents, was dif­fer­ent chem­i­cal­ly than the Pfiz­er-BioN­Tech vac­cine.

“While we all might say, oh there’s an LNP here, there’s a lipid and mR­NA, there­fore they must be all be the same,” he said. “I would not nec­es­sar­i­ly as­sume that.”

The on­ly point of con­tin­u­al fric­tion be­tween Mod­er­na and the pan­el arose around the ques­tion of what the com­pa­ny should do with their Phase III tri­al af­ter an EUA is is­sued. The group was skep­ti­cal last week when Pfiz­er pro­posed grad­u­al­ly un­blind­ing par­tic­i­pants as they be­come el­i­gi­ble for vac­cine un­der CDC pri­or­i­ty guide­lines. Mod­er­na want­ed to go fur­ther, im­me­di­ate­ly of­fer­ing the vac­cine to all place­bo par­tic­i­pants, re­gard­less of whether they would be el­i­gi­ble.

Mod­er­na ex­ec­u­tives said that they need­ed to un­blind to pre­vent vol­un­teers from drop­ping out of the study, and be­cause place­bo par­tic­i­pants are and would con­tin­ue to be in­fect­ed. They said they could vac­ci­nate them with clin­i­cal sup­ply of the vac­cine that would not draw from their com­mer­cial sta­ble.

“Ad­di­tion­al se­vere cas­es and death are a ques­tion more of when than a ques­tion of if,” Mod­er­na se­nior vice pres­i­dent Jacque­line Miller said.

Many ad­vi­sors re­ject­ed the ap­proach, propos­ing that Mod­er­na ei­ther fol­low Pfiz­er’s plan or adopt an ap­proach where the tri­al would stay blind­ed but par­tic­i­pants in the vac­cine arm would get place­bo and vol­un­teers in the place­bo arm would re­ceive vac­cine, al­low­ing com­par­isons on dura­bil­i­ty and long-term ad­verse events. A few, how­ev­er, backed the Mod­er­na ap­proach, say­ing the blind­ing pro­pos­al and even the Pfiz­er ap­proach may be in­fea­si­ble.

The de­bate got to the point that at least two dif­fer­ent ad­vi­sors pro­posed the agency al­low the pan­elists to vote on the is­sue, al­though they had not orig­i­nal­ly been asked to do so.

“It seems to me that there’s an as­sump­tion that Mod­er­na is go­ing to do what it’s go­ing to do. It doesn’t have to be that way,” Shel­don Taub­man, the con­sumer ad­vo­cate on the pan­el, said. “We weren’t asked to vote on it, but we could vote on it.”

Mar­i­on Gru­ber, di­rec­tor of the of­fices of vac­cine re­search at the FDA, though, neu­tral­ized that idea, cit­ing the “com­plex­i­ty of the sit­u­a­tion” and the fact that they did not ask the com­mit­tee to vote on the same is­sue at the Pfiz­er tri­al. The hear­ing end­ed with­out a res­o­lu­tion.

“I think we gave FDA a sense of our with that we could do a crossover blind­ed de­sign, but the re­al­iza­tion that that may be im­pos­si­ble,” com­mit­tee chair Arnold Mon­to said. “FDA will be ne­go­ti­at­ing with Mod­er­na about the way they will ad­dress this prob­lem.”

David Livingston, the Dana-Farber/Harvard Med scientist who helped shine a light on some of the key molecular drivers of breast and ovarian cancer, died unexpectedly last Sunday.

One of the senior leaders at Dana-Farber during his nearly half century of work there, Livingston was credited with shedding light on the genes that regulate cell growth, with insights into inherited BRCA1 and BRCA2 mutations that helped lay the scientific foundation for targeted therapies and earlier detection that have transformed the field.

The FDA late Wednesday signed off on authorizing the use of heterologous — or what FDA calls a “mix and match” of a primary vaccine series and different booster doses — for all currently available Covid-19 vaccines, in addition to separately authorizing Moderna and J&J boosters.

On the mix-and-match approach, which FDA officials insisted isn’t too confusing in a press conference, the agency offered the example of an 18-year-old who received the J&J shot at least two months ago and may now receive a single booster of the J&J, a half dose of the Moderna, or the Pfizer-BioNTech booster.

Production problems at a Novavax facility in Maryland have led to delays in the Covax vaccine sharing program. Now, a shortage of 1 billion doses is expected, as the supplier tries to navigate producing a shot up to regulators’ standards, Politico reported Tuesday.

The company has run into trouble with the purity of the vaccine. Novavax has had trouble proving it can produce a shot consistently up to standards, and it has caused significant delays in the rollout to low- and middle-income countries. This follows several delays at Novavax that has put the executive crew on the defensive.