3 ms·

It's quite literally one of the first things mentioned in the trial protocols and journal articles https://clinicaltrials.gov/ct2/show/NCT04516746 https://clin

by m-ee 6y ago

It's quite literally one of the first things mentioned in the trial protocols and journal articles https://clinicaltrials.gov/ct2/show/NCT04516746 https://clinicaltrials.gov/ct2/show/NCT04516746 "The efficacy of 2 IM doses of AZD1222 compared to placebo for the prevention of COVID-19 in adults ≥ 18 years of age [ Time Frame: 1 year ] A binary response, whereby a participant is defined as a COVID-19 case if their first case of SARS-CoV-2 RT-PCR-positive symptomatic illness occurs ≥ 15 days post second dose of study intervention. Otherwise, a participant is not defined as a COVID-19 case." https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32661-1/fulltext https://www.thelancet.com/journals/lancet/article/PIIS0140-6... "The primary efficacy analysis included symptomatic COVID-19 in seronegative participants with a nucleic acid amplification test-positive swab more than 14 days after a second dose of vaccine. "

m12k 6y ago
I think you're right, now that I know what to look for. The AZ/Oxford vaccine has lower symptomatic efficacy than the mRNA ones, and it's asymptomatic efficacy is lower still. We don't know what the asymptomatic efficacy of the mRNA vaccines is yet, but since their symptomatic efficacy is higher, it would be reasonable to expect their asymptomatic efficacy to also be higher. So at the end of the day, the main question regarding the AZ/Oxford vaccine is whether a half-dose starter shot regimen, or longer time between doses can bring its efficacy more consistently up around 90%, which would make it only slightly less effective than the mRNA ones, or if it's efficacy is actually just lower.
- m-ee 6y ago
  The half dose and longer time efficacy numbers have confidence intervals around 50-60% wide, definitely need to do more testing on that. I agree its the biggest question to answer for them (aside from just getting cleaner data through the US trial that will hopefully report soon). I believe they were also doing a study with mixed doses of Oxford/Sputnik.
kelnos 6y ago
The links you provided seem to be for AstraZenica's vaccine, though, not for Moderna's or Pfizer's (which is what 'm12k was originally talking about). That seems to suggest that Oxford/AZN were only testing symptomatic trial participants, no? And says nothing about what Moderna or Pfizer were doing?
- m-ee 6y ago
  Moderna and Pfizer/Biontech did not do regular screening to check for asymptomatic cases, aside from some samples taken in between the shots. Oxford/AZ did regularly screen some participants, but the primary efficacy analysis only looked at symptomatic cases similar to the mRNA vaccines.
  - kelnos 6y ago
    Ok, but the question in the thread was about sources showing that Moderna & Pfizer did not do regular screening; seems like no one had found that info earlier, but I now see someone downthread has posted more about this.

by m-ee 6y ago

m12k 6y ago

I think you're right, now that I know what to look for. The AZ/Oxford vaccine has lower symptomatic efficacy than the mRNA ones, and it's asymptomatic efficacy is lower still. We don't know what the asymptomatic efficacy of the mRNA vaccines is yet, but since their symptomatic efficacy is higher, it would be reasonable to expect their asymptomatic efficacy to also be higher. So at the end of the day, the main question regarding the AZ/Oxford vaccine is whether a half-dose starter shot regimen, or longer time between doses can bring its efficacy more consistently up around 90%, which would make it only slightly less effective than the mRNA ones, or if it's efficacy is actually just lower.

m-ee 6y ago
The half dose and longer time efficacy numbers have confidence intervals around 50-60% wide, definitely need to do more testing on that. I agree its the biggest question to answer for them (aside from just getting cleaner data through the US trial that will hopefully report soon). I believe they were also doing a study with mixed doses of Oxford/Sputnik.

kelnos 6y ago

The links you provided seem to be for AstraZenica's vaccine, though, not for Moderna's or Pfizer's (which is what 'm12k was originally talking about). That seems to suggest that Oxford/AZN were only testing symptomatic trial participants, no? And says nothing about what Moderna or Pfizer were doing?

m-ee 6y ago
Moderna and Pfizer/Biontech did not do regular screening to check for asymptomatic cases, aside from some samples taken in between the shots. Oxford/AZ did regularly screen some participants, but the primary efficacy analysis only looked at symptomatic cases similar to the mRNA vaccines.
- kelnos 6y ago
  Ok, but the question in the thread was about sources showing that Moderna & Pfizer did not do regular screening; seems like no one had found that info earlier, but I now see someone downthread has posted more about this.