If we think about this globally - just how difficult its going to be to get the vaccine to most of the world - I do think it is very much worth taking a couple more months and trying the same study in people who otherwise wouldn't be first in line. We can only gain from it. 2/2
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What about an immediate call for volunteers for a randomized group among the many millions who'll get the first shot? Data-wise, some of the initial groups aren't that high risk at the moment (<65 HCWs). The vaccine shortage is going to have huge implications on overall deaths.
2 replies 6 retweets 27 likes -
Yes, this is exactly what is meant by a follow on study to assess the non-inferiority of a single dose. I think we’re all saying the same thing! This is worth studying further in a rigorous trial. But I don’t think we should tinker with the current rollout for EUA populations.
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Agree. And we should remain open to change SHOULD additional studies suggest it is better for public health. I worry once we get something set, its incredibly difficult to change. Heck, we can't even get FDA to recognize that antigen tests don't look for residual RNA.
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Exactly. I think the idea that single dose may offer a reasonable, potentially excellent, trade-off is something to get out there right now because once something is set as standard, it's practically impossible to change even if it means billions are denied vaccination in 2021.
1 reply 2 retweets 14 likes -
Replying to @zeynep @michaelmina_lab and
Rajeev Venkayya MD Retweeted Prof. Akiko Iwasaki
Agree with supply urgency, but wouldn't overstate what we know about efficacy of a single dose. Second dose is likely to help with *magnitude* and *quality* of immune response through affinity maturation. 1/https://twitter.com/VirusesImmunity/status/1336323016737755142?s=20 …
Rajeev Venkayya MD added,
Prof. Akiko IwasakiVerified account @VirusesImmunityThe estimated vaccine efficacy after the 1st (82%), between 1st and 2nd (52.4%) and after the second dose (95%) are all impressive! However, high affinity Ab and long term immunity likely require the 2nd dose and we should all adhere to the recommended regimen. (2/n) pic.twitter.com/hSmSURkVTDShow this thread1 reply 0 retweets 4 likes -
Replying to @rvenkayya @zeynep and
Rajeev Venkayya MD Retweeted Deepta Bhattacharya
The good news is that we can study “missed 2nd dose” in the Ph3 and post-authorization populations, and hope to have a correlate of protection soon to make single dose studies easier without efficacy studies. 2/https://twitter.com/deeptabhattacha/status/1337147845686611968?s=20 …
Rajeev Venkayya MD added,
Deepta Bhattacharya @deeptabhattachaAfter the second Pfizer dose, the nAb titers go up 10-20-fold (https://www.nejm.org/doi/full/10.1056/NEJMoa2027906 …). That leaves a lot of room for decline while still maintaining protection. Even if every antibody-producing cell died en masse, all at once, theShow this thread1 reply 1 retweet 8 likes -
Replying to @rvenkayya @zeynep and
Rajeev Venkayya MD Retweeted
So fully agree this needs to be studied, but until we have the data, we shouldn’t give the impression that one dose of this vaccine is just as effective as two. It could undermine compliance with vaccine schedules beyond this one. 3/ https://twitter.com/K_G_Andersen/status/1337160738851287040?s=20 …
Rajeev Venkayya MD added,
This Tweet is unavailable.1 reply 0 retweets 2 likes -
Replying to @rvenkayya @michaelmina_lab and
I don't see anyone suggesting "effective as two" or not communicating the uncertainty. But if single dose is not put on the agenda soon, to be trialed ASAP, it will never happen because that's how it works. We're looking at a difference of billion+ vaccines in 2012.
@K_G_Andersen1 reply 0 retweets 5 likes -
Replying to @zeynep @rvenkayya and
That we didn't immediately launch a third arm for single-dose soon after the initial data were in—despite looking at a terrible fall/winter ahead—tells us how it works. I think our inability to adapt—with data—cost us so much already in this pandemic.
1 reply 0 retweets 2 likes
(Missed second dose in phase III for Pfizer is ~1250 which is a small number but is matched by almost equal size miss in placebo arm, suggesting some randomness, and maybe can help signal alarm: if big spike in disease, that's info).
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