First some terrible news these two brothers who we gave apples and masks to last week when Lynn and I went out to the campo....
Arturo on the left who is 13 was struck by a hit and run driver in the campo two days ago and he is in a coma in the hospital...his family and the villagers are devastated and are on a vigil outside the hospital...your thoughts and prayers please for this little guy!!
We are going to the village again tomorrow with food we will also donate some money and clothes to the family!!
My best buddy Larry who I have known for 40 years celebrates his birthday today.....he and Gail are always in Mexico this time of the year and I usually drive to the beach to celebrate with them but not this year they are back in Kelowna.....hope you have a great day..
This shot was taken a few years ago on his birthday with their daughter Kim....
I was on the courts again this morning for another couple of hours of good tennis and fun!!
Afterwards picked up another couple of donations and then home for the rest of the day.
This makes good and interesting reading...
COVID-19 Vaccine Efficacy Explained - It's Not What You Think
Unless you’ve been completely off the information grid for the past few months, you’ve certainly heard the life-saving news that multiple leading vaccine contenders are posting big results. You’re hearing about vaccine candidates with efficacy results ranging from 50-95%. I’m not a vaccine developer, but based on everything I’ve been reading, this seems like an absolutely major success that we should all be celebrating. And it should come as no surprise that many people feel and verbalize that they only want to get a vaccine with the highest efficacy.
So, we thought help you understand what those efficacy numbers actually mean. And we’ll fully admit that when we first read the news stories about these vaccine candidates, we did not interpret those values correctly at all...and we’re guessing neither did you.
Welcome to drug efficacy demystified
For the purposes of this article we’ll use the two earliest approved vaccines: Moderna’s mRNA-1273 and Pfizer-BioNTech’s BNT162b2. We’re going to try debunk what we think is the most common incorrect interpretation of those efficacy numbers and then explain to you what they actually mean. And once you have a better understanding of efficacy, it will also help you to understand why it may not be the only important number to look at.
When I first saw for example Pfizer, 95% and Moderna 94.1% efficacy I immediately thought that the interpretation of those values meant that if I’m vaccinated, that the likelihood that I get COVID-19 after being exposed to it dropped by 95% or 94.1 % depending on which vaccine I got. In other words, once vaccinated, if someone sprayed COVID-19 in my face, I’d only be about 5% likely to actually get infected. That seems sensible when we talk about efficacy and in other contexts, that is EXACTLY what efficacy means.
For example, if I have an antibacterial soap that claims to kill 99% of germs, we correctly interpret that to mean that of all the bacteria on our hands, the soap will kill 99% of it. It’s 99% effective at killing bacteria. If I have a manufacturing process that detects 95% of all defects before a product is completed, that means it is stopping 95% of problems from going through to the consumer. It’s 95% effective at stopping defects.
And yet that is not at all what is meant by efficacy with vaccines or drugs of any kind. In the medical testing world, efficacy has a totally different meaning. When drug companies test vaccines, they conduct double blind, randomized, controlled trials. Basically, they randomly assign some people to get a vaccine and some people to get a harmless saline injection, otherwise called a placebo. Neither the doctor nor the nurse administering the shot, nor the study participants known which one they’re getting and only when the study is completed, do the results become known. Once injected, they follow hte participants to see if they naturally develop symptoms of COVID-19. And it should make sense that it has to be this way, because they can't recruit participants, give half of them an unproven vaccine, half a placebo and then spray them with a deadly virus. It's far too dangerous making a different method of testing necessary. This is absolutely the best way to test vaccines and the hope is that the people who get the vaccine injection experience far less disease than those who got the placebo.
If that’s the case, we can conclude that the vaccine is effective. Notice when I saw effective here, I am referring to the relative effectiveness of the placebo to the vaccine and NOT the effectiveness of the vaccine in people given the virus. And that is actually what is meant by effectiveness in these vaccine trials.
To unpack this, let’s look at some actual data that from these two companies.
Pfizer-BioNTech had 43,448 people receive two doses of their vaccine when they released their results. Of those 43,448 people, 170 were infected with symptomatic COVID-19. Critically though of those 170 people, 162 were in the placebo group and 8 were in the vaccine group (Fernando P. Polack, 2020). In other words, you were far less likely to get infected if you got the actual vaccine than if you got the harmless saline injection.
So where does the 95 %efficacy come from?
It comes from comparing the number of people infected across the two groups. Of the 170 total infections, 162 were in the placebo, so we take 162 and divide it by 170 and that’s where you get the 95%. That’s the efficacy number they are reporting.
For Moderna, it is the same story. Somewhere around 30,420 people received 2 doses of their vaccine or 2 doses of the placebo. Ultimately, 196 were infected with symptomatic COVID-19. 185 were in the placebo condition and 11were in the vaccine condition (Lindsey R. Baden, 2021). 185 divided by 196 gets you 94.1% which is the efficacy number reported.
To be clear, this is absolutely the standard way to report efficacy in vaccine trials. And yet I find this to be very confusing because it just doesn’t align with how we think of efficacy. When I hear 95% efficacy, I think I’m only 5% likely to get infected once I get the vaccine. But that’s not actually quite right. That 95% doesn’t say anything about how likely you are to get infected after exposure.
Instead. one way to look at it is to think about how many people of those who received the vaccine actually got infected. If we do that, we see that for the Pfizer vaccine, about 8 out of 21,720 people or just 0.04% were infected with symptomatic COVID. We can compare that to the control group, where 162 out of 21,728 people were infected or 0.75%. In other words, we can think that our likelihood of infection actually goes down by a full order of magnitude. From about 0.75% to 0.04%. And you get basically the same results from the Moderna vaccine; from about 1.28% to 0.07%.
The reason why 95% doesn’t mean the same thing to all vaccines
But even that conclusion isn’t enough to match the intuition for effectiveness that I think we all want. And that’s because we don’t know what populations that people who were studied came from. As in, we need to know the baseline level of disease in each of the areas where these companies tested their vaccines.
If the infection rate in those areas were very high, then the vaccines would be highly effective .at least in the more intuitive sense of effectiveness. If the disease outbreak was relatively low, then it’s a lot harder to say. If variants were spreading during the time of trials, the numbers again become a little more difficult to compare. With J& J for example, the overall efficacy of their vaccine was 66%, a number much lower than that of Moderna and Pfizer-BioNTech. However, their study included participants from South Africa where nearly all cases of COVID-19 (95%) were due to infection with a SARS-CoV-2 variant from the B.1.351 lineage (Johnson & Johnson, 2021), which neither of the other two included. And the fact that primary endpoints for all of these studies ONLY looked at symptomatic COVID-19, doesn’t tell the full story because it excludes asymptomatic individuals.
Take away
The point is that YES we should absolutely celebrate these amazing medical breakthroughs and as the safety of these vaccines continue to be verified, we should all be lining up to get vaccinated so we can work to end the horror of this global pandemic. And yet, while we do that, we should be fully informed about what the data backing these vaccines tell us. When we hear amazing results like 94.1 and 95% effectiveness, we need to understand what is being described is the ratio between the vaccinated and placebo group infection rates and NOT how effective the vaccine is at actually preventing you from getting infected with COVID 19. Nor does it tell us that this vaccine is better than a vaccine that produces 66% overall efficacy unless all things were equal in the design of the trial…which they were not. Again, this is not an inditement on vaccines, far from it. It’s a call to action for you as the consumer of this information to make sure you fully understand what you are seeing.
As approval bodies vet and confirm that these vaccines are as safe and effective as they claim to be they WILL reduce the likelihood of anyone getting the vaccine from getting sick with COVID-19. But how much will that likelihood decrease ISN’T 66, 94.5 or 95%. We actually don’t know exactly how much it will reduce infection likelihood, but assuming they are safe…Any significant reduction is likely to help billions of people around the world.
And one REALLY important piece of information that none of these numbers highlight is this. All vaccines trials to date, regardless of reported efficacy, have been able to prove, that even though certain participants developed symptomatic COVID-19 after receiving the vaccine, not a single one in all of the studies developed severe disease and not a single participant that received the vaccine died from COVID-19.
And this, is the true miracle of these drugs and is why when your chance for a COVID shot comes…..don’t worry so much about the numbers.
In closing, I wish all of you to be safe, healthy and diligent in fighting this disease while we wait for these vaccines to be fully vetted and distributed
This shows one of the reasons I spent so many years in Bermuda....simply beautiful.
Stay safe and healthy!!
Yashi Kochi!!!
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