This effectiveness seems much higher than I’ve seen other places, but it’s the WHO. Is this number right?
Bumped, because I’d like to know as well.
Ditto.
Welcome to SDMB, and thank you for posting this question. I’ve been wondering about this since I heard Dr. Campbell mention it on one of his youtube videos. I’ve asked a few doctors/clinicians who all cut me off to parrot the standard “mask usage lecture for the masses”. Dr. Campbell also mentioned that the two week efficacy is age-related, and 60+ should not expect protection until the 3 week mark.
Apologies, I can’t find the specific videos where he covered this.
There a discussion of a single dose’s efficacy at about 10 minutes in on this video.
See details of the FDA assessment of the vaccine (here, PDF document), specifically Table 15 on page 30.
Additional analyses were done to assess efficacy against COVID-19 after one dose of mRNA1273. In participants in the mITT [intent to treat] set who only received one dose of the vaccine at the time of the interim analysis, VE [vaccine efficacy] after one dose was 80.2% (95% CI 55.2%, 92.5%). These participants had a median follow-up time of 28 days (range: 1 to 108 days). The small, non-random sample and short median follow-up time limits the interpretation of these results. There appears to be some protection against COVID-19 disease following one dose; however, these data do not provide sufficient information about longer term protection beyond 28 days after a single dose.
My bold. From the table:
(>) 14 days after dose 1:
2 / 983 patients in the vaccine group caught COVID (0.2%) (87.2 person years of follow-up)
28 / 1059 patients in the placebo group caught COVID (2.6%) (96.2 person years of follow-up)
Efficacy 92.1% (95% confidence interval 68.8% to 99.1%)
j
Treppenwitz, thank you.
I’m little unclear from the report whether people are “catching” Covid up to 14 days after the first dose or testing positive/becoming symptomatic. Obviously, those are very different.
I feel it must be testing positive/becoming symptomatic, which would suggest that the immune response is starting earlier and is pretty robust 7-10 days after the first dose. With a mean period of 5 days to become symptomatic/test positive after contract. If test positive on day 11, you probably caught it day 6. And incubation commonly goes 11 days, but don’t really any data to suggest caught it day 7 and testing positive day 18.
This suggests pretty good immunity about 7 days after dose 1. (The cumulative positive number flattens for the vaccine group at 12 days).
Unless I’m getting this all wrong.
The efficacy result is based on cases recorded from 14 days after treatment, for patients who have been vaccinated or given placebo (single dose). From that point efficacy is based on recorded cases of “protocol defined COVID-19” in the active and control groups. So far as I can tell, recorded cases may include those where infection occurred before the day 14 cut-off but will exclude cases detected prior to day 14.
Definitions of COVID-19 are given on p14 et seq of the linked document. As what we are discussing is listed under “Other Secondary Efficacy Endpoints” I assume the appropriate definition is given under “Secondary Efficacy Endpoints” on page 15 - though this section includes two definitions, and it isn’t clear to me which one is being applied in this particular case.
j
If I understand that correctly, if the covid was detected before day 14 then it is included in the less than day 14 numbers. So the substantial immunity is kicking in before day 14.
There is always going to be lag between exposure/infection and detection. Basically, we should look at five days prior to date we see detection numbers drop off to see when immunity kicked in.