Great News! Moderna says its Covid19 vaccine is 94.5 % effective!

[DCLPrincess]

This is not how the placebo method works.

Let's say people were not social distancing and were without masks - and, thus, were exposed to a potentially higher virus load. Your placebo group would then end up with 180 infections and the treatment group with 10 infections. (Maybe - it's a prediction based on a sample.) Your conclusion would not change unless it can be demonstrated that those in one group somehow got a higher exposure.

Things to keep in mind:

1 There is no scientific study proving that someone wearing a mask (and distancing socially) would get a virus that is somehow different from the virus in others.
2. The participants in the study are being tested using PCR tests at multiple points in time. While a lower exposure could result in less severe symptoms, the PCR tests would still catch the virus with a high accuracy as long as it was transmitted.
3. The mask mandates and social distancing measures will likely be removed only when the virus transmission rates are already low.

If without masks more people in both groups got the virus then that would mean it's not 95% effective. I'm not saying the vaccine doesn't work but unless you actually infect people with the virus you can't know effectiveness until it's in mass usage. I believe in science but there are many variables including participants habits. Do they wear a mask? Do they work from home? Do they travel?

 

[Intr3pid]

If without masks more people in both groups got the virus then that would mean it's not 95% effective. I'm not saying the vaccine doesn't work but unless you actually infect people with the virus you can't know effectiveness until it's in mass usage. I believe in science but there are many variables including participants habits. Do they wear a mask? Do they work from home? Do they travel?

I would encourage reading up on what a placebo method is - or, for that matter, how the math works (180 vs 10 is the same ratio as 90 vs 5). The questions you are posing are largely irrelevant if the controlled study is well designed.

 

[DCLPrincess]

I would encourage reading up on what a placebo method is - or, for that matter, how the math works (180 vs 10 is the same ratio as 90 vs 5). The questions you are posing are largely irrelevant if the controlled study is well designed.

I'm not comparing the covid cases of placebo vs vaccine. I'm comparing it to the total number of participants. The more people out of the 30,000 participants that get covid increases the percentage rate. Many South American countries saw a decrease in flu cases because of covid precautions does that mean the flu vaccine was more effective this year?

 

[GoofyDisneyDaddy]

I'm not comparing the covid cases of placebo vs vaccine. I'm comparing it to the total number of participants. The more people out of the 30,000 participants that get covid increases the percentage rate. Many South American countries saw a decrease in flu cases because of covid precautions does that mean the flu vaccine was more effective this year?

You are making the wrong comparison, though. The real question is to compare those who got the flu vaccine against those that didn’t and evaluate the effectiveness between the two. Because of covid, flu may be less prevalent in both groups compared to a normal year, but the effectiveness is comparing the placebo group against the group that got the vaccine.

For some simple math example, let’s say in a normal year 10% of folks will be exposed to the flu. Let’s assume two populations of 100,000 people - with 100,000 taking the vaccine and 100,000 not. 10% or 10,000 of each population will be exposed to the flu. If the flu vaccine is 50% effective, in a normal year, the vaccinated population will see 5,000 infections and the unvaccinated population will see 10,000. That is the 50% effectiveness number. Now let’s say this year only 1% will be exposed due to social distancing and masks. So, in the vaccinated population you’ll see 1,000 exposed and 500 infected. In the unvaccinated population you’ll see 1000 exposed and 1000 infected. You still can see the effectiveness rate of 50% even though the numbers infected, in both populations, is way down.

And that is how we now have the covid vaccine effectiveness rate. We don’t need to know the exposure rate, we’ll assume both populations were equally exposed, and then we can compare how many got sick in the placebo vs vaccinated group to back out the effectiveness rate.

 

[Intr3pid]

I'm not comparing the covid cases of placebo vs vaccine. I'm comparing it to the total number of participants. The more people out of the 30,000 participants that get covid increases the percentage rate. Many South American countries saw a decrease in flu cases because of covid precautions does that mean the flu vaccine was more effective this year?

No, the 94.5% number you are quoting is not telling you anything about the percentage of the population getting exposed. Here is how it worked.

Of the 15,000 placebo participants, 90 got the virus. Of the 15,000 participants who had the real drug, only 5 got the virus. So, this drug was presumably able to prevent virus incidence in 85 out of the 90 in the second group. That's 85/90 = 94.5%. If you remove masks and social distancing, you may end up doubling or tripling the virus incidence in both groups - but that's not going to change the 94.5%. Try it out yourself with new numbers.

To be sure, both groups were made up of a diverse set of participants - by way of demographics, social contact, geography, travel habits, etc. Or at least that's what we would assume with a well designed study.

Anyways, this is my last attempt at explaining it. If you are still skeptical, I would encourage doing your own research - and just ignore me.