At least in the United States, the delta variant has popped up and that's what we're going to talk about. But even more importantly, let's talk about variants in general. So if you've got a coronavirus and specifically the SARS-CoV-2 virus and it goes to infect an individual, the issue is as we've talked about before the virus is going to hijack your cells to produce many more copies of itself.
In fact, in some studies it's been shown that the virus will make up to a billion copies of itself in just one individual, but here's the problem: the way that it does it is not very accurate and so there will be some slight mistakes, and you might see a variant being produced in these infections.
Now imagine those 400,000 cases each producing over a billion copies,
and you can see there that it's only a matter of time before you get a mutation that is fortuitous for the virus, and you can see here very easily that a mutation that allows the virus to infect better and be more contagious is going to be a virus that is certainly going to take over the world. In terms of the different types of variants, so while there may be many different variants at once if there is a variant that is able to infect better. And that's really all that matters to the virus, is to spread its genetic material as far and wide as it possibly can. That is the virus variant that is going to win in terms of the prevalence in the population, and again this mutation that causes increased fitness can be manifested as better binding or evading the immune system. There's a number of different ways that this can happen, so as it turns out, this delta variant has some characteristics of it and it's known as B.1.617.2. It seems that it is more contagious than the original virus to give you an example.
Some experts have said that if you look at the original virus,the number of people that one person would have infected otherwise, known as the R-naught (R0), it was originally around 2.5. This delta variant has been estimated anywhere between 3.5 and 4.0. Okay, so it seems to be more contagious, but
where does it seem to be found the most?
Well, there was another paper that was published. This paper was known as the "REACT-1
round 12 report," and while it has not been published or peer-reviewed as yet, there are some interesting findings. This was put out by the Imperial College in London in the United Kingdom, and what they found is that the prevalence of the delta variant in those aged 5 to 49, in other words, those people less than 50 years of age, was two and a half times higher compared to those that were age 50 years and above. And so while it is possible that people over the age of 50 are more likely to be vaccinated, there could also be a connection between this virus and younger aged individuals. All right, what about hospitalization? Well, there was a correspondence that was published in the Lancet regarding the delta variant, and they were able to look at PCR, and what they found was surprising. What they found, essentially using a Cox regression analysis, which is a way of adjusting for age, sex, and economic status, temporal trend comorbidities, was that the delta variant had a 1.85 times higher risk of getting the person infected in the hospital with severe COVID-19. So if you look at the SARS-CoV-2 infection since April in the United States, you'll see here that the British variant, or the UK variant, the B.117, has been up to this point the most dominant infection. But as of recently, there is one that is taking over very quickly, and that is the delta variant. And as you can see, the delta variant has made some inroads very quickly here in the last two to three months. And the reason for that is because it is the most infectious variant that is currently there in the UK, where greater than ninety percent of the cases are the delta variant. It is what is fueling the latest surge. At least 60 percent of the population is vaccinated with two doses, which is actually very good, and despite the fact that the cases have gone up in England and in Wales, Scotland and Northern Ireland, the good news is that the corresponding deaths have not come along with that surge as yet. In Israel, where they've done a tremendous job of vaccinating, primarily with the very effective Pfizer-BioNTech vaccine, there has been only a small recurrence of cases, at this date, most of them from the delta variant. So where we stand here in the United States is that there has definitely been a resurgence and a doubling of the number of cases, which is an early sign that there's something potentially coming, and we are seeing here on the daily deaths chart that for the first time, daily deaths have stopped going down and are now starting to creep up.
In California, and specifically in Southern California, where I practice, there has been a
recent resurgence of cases of SARS-CoV-2. Daily deaths have not yet picked up, but I can tell you anecdotally, in the hospitals that I work at and in the friends that I have, some of them in LA County, there has been an increase in the number of admitted cases. For instance, one hospital where I work at had not seen COVID-19 patients in months, literally, are now admitting patients with COVID-19 and some of them are requiring high levels of oxygen. So given that, what are the tools that we have? How well equipped are we with the different vaccines that are available against this delta variant? Let's review the data up to this point.Now we know that there are several different types of vaccines in the world. We're going to talk about these four mainly, because we have recent data that shows the efficacy of these vaccines against the delta variant: that is the Pfizer-BioNTech vaccine, the Moderna vaccine, the Oxford-Astrazeneca vaccine and the Johnson & Johnson vaccine, and they are different. The Pfizer-BioNTech and Moderna, of course, are messenger RNA vaccines, and the Oxford-AstraZeneca and the Johnson and Johnson are DNA that use adenovirus as the vector. And if you have more questions about that, look at our previous MedCram videos on those particular vaccines for more information about how they work. Now, as you know, these three first vaccines are first and second shot, and the Johnson & Johnson vaccine is a one-time shot. Now, there's two different categories that I want to refer you to, and the first category that we're going to talk about is infection. So infection, what I mean by that is: does the vaccine prevent the individual from being infected, and therefore prevent them from spreading it onto somebody else? That has great epidemiological importance in terms of stopping that R-naught (R0) number and preventing the infection from spreading epidemiologically, And, of course, who wants to get sick? Nobody does. But there's another important endpoint as well, and that's hospitalization. Does the vaccine prevent the most serious complications of getting SARS-CoV-2, which is of course COVID-19, hospitalization?
High flow oxygen and ventilation, ARDS, things of that nature, and so those are going to be
two different numbers. So let's talk first of all about the Pfizer-BioNTech vaccine. Now, I'm going to be referencing a number of articles. Some of them have not been peer-reviewed, but it is recent data. I will give a link to all of these studies in the description below. So there was a UK study that showed after the first dose -- so we're talking about usually two weeks after the first dose -- the Pfizer-BioNTech vaccine, regarding the delta variant, I'm talking about the delta variant now, specifically was 33 percent effective after the first dose and 88 percent effective after the second dose at preventing symptomatic infection, and that was the UK study. Now there was a Canadian study that came up with slightly different numbers
that was 56 percent after the first dose and 87 percent after the second dose. There was an Israeli study that showed after the second dose, they got 64 percent, and there was a Scottish study that showed 79 percent. Now all of these are above 50 percent and would have been approved if this were the original virus, so I think these are all very good numbers. And again, we're talking about infection. Now, remember that the primary way that your body prevents infection is antibodies, and we know that the mutation that has caused this variant may be slightly off enough that some people's antibody responses may not be good enough at preventing infection, but remember that one of the things that helps you prevent getting worse is T cell activation. When T cells are replicated in the human body, they also are replicated in a way that is not perfect, so it allows for variance in the T cells, and so if you have variants in the virus and variants in the T cells, that will sometimes allow for a bit of change. The T cells can be effective at reducing hospitalizations and taking care of cells that are already infected, and therefore what we typically find is that the hospitalization numbers are usually much better. So that same UK study found that after the second dose, there was a 96 percent prevention of hospitalization and death if you got the Pfizer-BioNTech vaccine after the second dose. And when I say prevent here, I'm talking about efficacy. So, in other words, if there's a 90 percent plus efficacy, that would be in comparison to a control, or where there's no vaccine, which would have a zero percent efficacy. There was a Canadian study that looked after the first dose, there was a 78 percent reduction in hospitalization after the Pfizer-BioNTech vaccination, and that was the Canadian study. You might be wondering why we don't have data after the second dose. There wasn't enough data points to make that available in the study so far. There was also an Israeli study that showed in terms of preventing hospitalization after the second dose that it was 93 percent effective at preventing hospitalization and death in Israel. So the bottom line here for the Pfizer- BioNTech vaccine is that, despite the fact that delta is more infectious and causes potentially more hospitalization, Pfizer is exceptionally good at preventing hospitalization and death from the delta variant. What about Moderna? Well, there was a Canadian study that showed that after the first dose, there was a 72 percent reduction, and that was the Canadian study. In that same study, after the first dose, the Moderna vaccine was 96 percent effective at preventing hospitalization and death.
Now the Oxford-AstraZeneca vaccine, which has been given authorization in the UK. After the first dose, they found it to be 33 percent effective at preventing infection. And after the second dose, 60 percent effective. That was the UK study. In Canada, where it's approved, they found that after the first dose, it was 67 percent effective at preventing infection, and that in Scotland, after the second dose, it was again 60 percent effective at preventing infection. Now what about hospitalization?
Well in that UK study, they found that it was 93 percent effective after the second dose, preventing hospitalization. In the Canadian study that they looked at, it was 88 percent effective at preventing hospitalization and death, if you took the Oxford-AstraZeneca vaccination. So again, very good numbers at preventing the worst outcomes. Now what about the Johnson & Johnson vaccine? That's a one-time shot. What they found is we don't have studies, currently, that look at the efficacy, but we do have some surrogates that could be very informative. Now, the Johnson & Johnson vaccine was tested against the most strenuous variant, or the worst variant at the time, back about six months ago, and that was the South African variant, and when they tested the antibody response of the delta variant in comparison to the South African variant, what it showed was that there was a higher level of antibody response to the delta variant than there was even to the South African variant. In other words, a very good antibody response to the delta variant.
You may recall the South African variant with respect to the Johnson & Johnson vaccine, there were no people who were hospitalized or died of the South African variant 49 days after they received the Johnson & Johnson vaccine. In fact, Johnson & Johnson put out a statement saying that as time went on, the immunity got better up to even eight months after the Johnson & Johnson vaccination. So because these vaccinations are so good at preventing hospitalization and death and also reasonable at preventing infection, your risk from the delta variant is going to be predicated on a couple of things: number one, it's going to be predicated on whether or not you're vaccinated. So it's also going to be predicated on the amount of people in your area that are vaccinated. If there's a high frequency of vaccination in the population around you, then you're going to be more protected and, of course, the question also is how prevalent is the delta variant in your community as well?
I highly recommend going to the CDC covid data tracker, which gives you up-to-date information in your county and also your state. There are a number of factors that could be in play: there is a change in humidity; there is the change in daylight hours; vitamin d production; being indoors versus outdoors. All of these may play a role in the resurgence of a potential delta wave.
I'd like for all of you out there to remain safe, get plenty of sleep, boost your immune system.
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