COVID Question for the Medical Folks

[Half Fast]

There has been a lot of debate regarding what the real likelihood of contracting COVID-19 is, and also much debate over how many cases become severe or life threatening. So far the data has been quite questionable due to differences in testing, in reporting, sampling bias, etc. In some cases political agendas may have distorted the data.

But maybe we have some good data now as a result of the vaccine trials.

Preliminary clinical trials have just concluded for two vaccines. The trials included over 40,000 people, half of whom received a placebo. The participants represent a range of ages, ethnicities, and so forth. The trials, to be meaningful, had to be consistent in testing for the virus and had to have a consistent definition of what a "severe" case is.

So what did we learn from the placebo group? The accuracy of the reported efficacy for the vaccines can be no better than the accuracy of data on the placebo group.

Shouldn't we now have a good idea what the probabilities are for unvaccinated people to catch COVID, to exhibit symptoms, to require hospitalization, or to die?

I haven't seen these placebo results reported in the media, so I'm hoping some of you knowledgeable physicians, biochemists, and researchers might have read the trial results and be able to shed some light.

Anybody?

 

[X3 Skier]

I’m not an expert but the actual number of people diagnosed with COVID in the Trials is pretty small. As a Lab Rat in the Moderna trial, AFAIK, nobody in my group has been diagnosed with the virus. The trial is to see how effective the vaccine is or isn’t, not so much what happens to the unvaccinated.

My opinion is the statistics for the Placebo Trial group won’t be any different than the Rest of the World. Just because they are tracked better shouldn’t be a major factor. Buy what do I know, I’m just a Lab Rat

Cheers

 

[Half Fast]

The trial is to see how effective the vaccine is or isn’t, not so much what happens to the unvaccinated.

But you don't know how effective the vaccine is without knowing what happens with the placebo group. Efficacy is based on the difference between the two groups, so the trial is meaningless if your data on the placebo group isn't just as accurate as that for the vaccine group.

My opinion is the statistics for the Placebo Trial group won’t be any different than the Rest of the World.

EXACTLY! That's the point. The data on the placebo group should give us accurate data that's representative of the unvaccinated world. Something everyone has been questioning for a while now. [/QUOTE]

Just because they are tracked better shouldn’t be a major factor.

It's a factor in how accurate and meaningful that data is.

 

[Matthew]

The Moderna numbers are on page 23, table 9. Is this the info you were looking for?

5 Covid cases in the vaccine group (18-65 age group) vs 90 in the placebo group.

90/13833 = 0.6%

https://www.fda.gov/media/144434/download

The Pfizer report is out there, too, but I didn't pull it down to look at it.

 

[weilke]

My opinion is the statistics for the Placebo Trial group won’t be any different than the Rest of the World. Just because they are tracked better shouldn’t be a major factor. Buy what do I know, I’m just a Lab Rat

Cheers

The trial plan I looked at included serology on both groups at certain points in time. By knowing who was seronegative and turned positive during the trial, you can get a better estimate of the rate of asymptomatic vs. symptomatic infections and infection fatality rate.
The serology data has not been published yet.

 

[Matthew]

Here's Pfizer

9 cases in the vaccine group

169 cases in the placebo group

(this is after the 2nd dose)

169/20172 = 0.8%

A little higher percentage of the control group in the Pfizer tests got Covid than in the Moderna group (0.8% vs 0.6%).

https://www.fda.gov/media/144245/download

 

[bdtaz]

Those in the Placebo group would be "Self Selecting" (they volunteered for medical research) so would likely not be a great sample to reflect a truly random population.

Volunteering for a medical study might be an indicator of other behaviors not in line with "typical behavior of the greater population".

Perhaps they are more likely to abide by mask mandates or are more "religious" about other aspects of virus avoidance than the population at large.

After all, they were enough "health aware" to chase a slot for a vaccine study.

 

[Ted]

Those above numbers are interesting to look at. According to worldometers.info we're at over 18M cases in the US as a whole, but that's since this started and not at all over the same time period. Actually, what's interesting is that looking at rough populations, it's more or less evened out to around 6% of the population nationwide has tested positive (my guess is significantly more have had it, and a bit under 2% of the cases have resulted in deaths.

I'm very interested in the OP's question too.

 

[Ted]

Those in the Placebo group would be "Self Selecting" (they volunteered for medical research) so would likely not be a great sample to reflect a truly random population.

Volunteering for a medical study might be an indicator of other behaviors not in line with "typical behavior of the greater population".

Perhaps they are more likely to abide by mask mandates or are more "religious" about other aspects of virus avoidance than the population at large.

After all, they were enough "health aware" to chase a slot for a vaccine study.

Yeah, I had that thought as well. If you volunteered you're probably in the group of people who are more likely to take a higher level of precautions in the first place.

 

[bdtaz]

Same thought applies to those in the "non-placebo" group.

The results are the impact of the vaccine on a population that volunteered for the study, not a truly random cross section.

 

[weilke]

Those in the Placebo group would be "Self Selecting" (they volunteered for medical research) so would likely not be a great sample to reflect a truly random population.

They are not only self-selecting, the trial organization actively went out to find people who matched a desired demographic in areas where the virus was spreading at the time. This study was geared to proving whether the vaccine is effective, it was not designed to answer questions about the underlying disease. We may get some of that data as a spin-off, but it'll be limited in use.

 

[Half Fast]

Those in the Placebo group would be "Self Selecting" (they volunteered for medical research) so would likely not be a great sample to reflect a truly random population.

Volunteering for a medical study might be an indicator of other behaviors not in line with "typical behavior of the greater population".

Perhaps they are more likely to abide by mask mandates or are more "religious" about other aspects of virus avoidance than the population at large.

After all, they were enough "health aware" to chase a slot for a vaccine study.

That would be equally true for the vaccine group, so if you're correct the efficacy may not be as good as reported.

 

[Half Fast]

They are not only self-selecting, the trial organization actively went out to find people who matched a desired demographic in areas where the virus was spreading at the time. This study was geared to proving whether the vaccine is effective, it was not designed to answer questions about the underlying disease. We may get some of that data as a spin-off, but it'll be limited in use.

The data on the effectiveness of the vaccine is obtained by examining the difference between the vaccine group and the control (placebo) group, otherwise there would be no need for the control group. Whatever the study teaches us about the vaccine group, it also teaches us the negative corrolary in the control group with the same accuracy and quality of the data.

 

[Sinistar]

Another weird thing that should somehow relate to all of this. Of the 20000...30000 that received the actual vaccine trial doses why did they not note nearly as many anaphylaxis events as the first 1000 or so doses seemed to call out in the past week? Its like people with certain underlying conditions (eg. alergic rx) tended to not apply for either group once again I think re-inforcing (lightly) what your are saying @Half Fast.

A lot of people might think of this like the flu vaccine where they give us a small amount. Maybe with Covid the people volunteering for trials were biased by this "flu like" thinking so a large portion opted not to do the trial out of fear of the severity of the vaccine itself. But then with approvals targeted a "medical professionals" vs "volunteers" they are seeing a more diverse group for the first time.

I wonder if in about 3 month they will publish the positivity rates for those electing to take the vaccine.

 

[PeterNSteinmetz]

I think the data from the trials is one good way to estimate that probability.

Another approach is just to take total new cases and divide by the population of the state. That is likely cruder as it allows a strong confound of the number of tests performed. Nonetheless, consider AZ, which has 5871 daily new cases on average over the last 7 days. Population of 7,286,000. So that is 0.08% per day.

If the exposure time of the Moderna group was 1 month plus two weeks, that would work out to 56 days, so one might expect 4.5% based on that average from Arizona, which is almost an order of magnitude higher than observed. Of course, these are in different timeframes.

 

[TCABM]

I’m pretty simple, so I keep going back to the cruise ship populations (there was more than just the Diamond Princess).

Other than a couple of near-term Lancet surveillance articles (which I found informative), I haven’t seen much on those populations.

Hopefully there will be more studies published ...unfortunately, like trial participants, it’s not a truly random pop, but those pops tend to be more reflective of the more at-risk pops (at least in my mind).

 

[Everskyward]

Yeah, I had that thought as well. If you volunteered you're probably in the group of people who are more likely to take a higher level of precautions in the first place.

I volunteered to be considered as a volunteer. They asked a bunch of questions that made me think they were looking for folks who would naturally get more exposure than other folks. They asked about your job and geographic location. I figured I would be a fail, because the place I live never had many cases, even though it's a city. I'm also not exposed to a large number of people in my daily life, especially after many things got canceled. I traveled, but not as extensively as some. I got one callback but they were looking for people >70.

 

[bflynn]

Question was raised about cruise ship populations - here is one study.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7403638/

I have not dived into this in depth, but a few things stand out to me.
- this started 20 Jan 2020, before it gained attention worldwide. The WHO had just tweeted the day before they believed there was limited capacity for human to human transmission.
- everyone was isolated Feb 7, so we don’t know what an unconfined spread of the virus looks like.
- 172 cases out of 490 tests of suspected cases.
- the asymptotic rate appears very low for what we know now.

not sure there is much more to be learned from this, other than amusement at what we didn’t know then.

 

[Matthew]

I volunteered to be considered as a volunteer. They asked a bunch of questions that made me think they were looking for folks who would naturally get more exposure than other folks. They asked about your job and geographic location. I figured I would be a fail, because the place I live never had many cases, even though it's a city. I'm also not exposed to a large number of people in my daily life, especially after many things got canceled. I traveled, but not as extensively as some. I got one callback but they were looking for people >70.

I don’t know all their selection criteria, but I’m going to guess they were trying to get a representative cross sample of ages, sexes, and races.

The FDA approval committee was not unanimous in their vote for the Pfizer vaccine. That vaccine was being approved for ages 16+, but 4 of 22 committee members did not feel there were enough 16-17 year olds in the test.

Moderna was tested and approved for 18+.

 

[PaulS]

Like anything, stats over a large population may not tell the whole story.

In my layman point of view this is a highly contagious virus, we know about it and many are taking precautions to prevent catching it. It seems to me the most effective way to prevent catching it pre vaccine is to avoid other people. Most people are doing this.

I've heard many anecdotal instances where people gather in a group in a small space, one of those people tests positive the next day because they had symptoms so the group gets tested a large population of that group tests positive, with many of them getting a range of symptoms from mild to severe.

It's a nasty virus.

 

[bflynn]

I don't believe it's necessarily more nasty than say the flu. The difference is, we have a vaccine for the flu and therefore it's not apples to apples. I suspect that without a vaccine, the flu would be even worse than covid given that we still get 30-60k deaths per year. With covid, we've had 320k deaths just shy of a year. With a vaccine that is 95% effective, that 320k number will be in the 10k order of magnitude.

Common sense - yes, wash your hands, be reasonable. Long term, I believe perhaps short term, masks should be a personal choice. For people with sensitivities to breathing, mask fibers are going to become problematic if they haven't already. The real reason they are recommending that we continue with masks is because if anyone gets an exception, everyone is going to take their masks off. Nobody wants to wear them.

 

[Ted]

I volunteered to be considered as a volunteer. They asked a bunch of questions that made me think they were looking for folks who would naturally get more exposure than other folks. They asked about your job and geographic location. I figured I would be a fail, because the place I live never had many cases, even though it's a city. I'm also not exposed to a large number of people in my daily life, especially after many things got canceled. I traveled, but not as extensively as some. I got one callback but they were looking for people >70.

I would imagine that in order to most accurately test the efficacy they would want people who are more likely to get exposed and thus more likely to contract the virus. Looking at raw numbers, I'm not sure whether 90 and 5 out of roughly 14,000 constitute significant exposure. But if you figure they did the trial over some obviously shorter time period than the entire 2020 year, maybe it's about the same as average.

Like anything, stats over a large population may not tell the whole story.

In my layman point of view this is a highly contagious virus, we know about it and many are taking precautions to prevent catching it. It seems to me the most effective way to prevent catching it pre vaccine is to avoid other people. Most people are doing this.

I've heard many anecdotal instances where people gather in a group in a small space, one of those people tests positive the next day because they had symptoms so the group gets tested a large population of that group tests positive, with many of them getting a range of symptoms from mild to severe.

It's a nasty virus.

Statistics never tell the whole story, and ultimately each of us individually is a sample size of 1.

 

[Matthew]

...I'm not sure whether 90 and 5 out of roughly 14,000 constitute significant exposure.

The US tests (Pfizer and Moderna) did not do any "challenge testing", where participants were intentionally exposed. I am pretty sure the UK entry, AstraZeneca also did not do challenge testing.

But the UK will be starting challenge testing in Jan.

https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30518-X/fulltext

https://ukcovidchallenge.com/covid-19-volunteer-trials/

This will test to find the minimum amount of the virus required to generate a response. This information could be used for further vaccine tests.