In fact, the vaccinated do not have as high a viral load as the unvaccinated when infected – HotAir



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Nate Silver was beat the drum about this study all morning, wanting to know why the American media do not give him same gasping attention he donated to the dubious Provincetown study on which the CDC’s new mask guide is based.

The main advantage of the UK analysis over US studies, he notes, is that it is based on a random sample of the population. The P-town and Wisconsin studies the CDC relied on used self-selected samples, drawing on data collected from infected vaccinated people who sought to get tested on their own – likely because that they had a case severe enough to show symptoms. But anyone who has been vaxxed and then ends up with a breakthrough infection will not have symptoms. In fact, most may not. We have no idea because, again, the Provincetown sample was not random.

It may be true, in other words, that symptomatic breakthrough infections produce viral loads in vaccinated people that are on par with viral loads in unvaccinated people, perhaps making them just as contagious to others. But that wouldn’t tell us anything about the contagiousness of the average breakthrough infection, which matters a lot to the CDC’s new universal masking recommendation. If it turns out that most vaxxed Americans aren’t as infectious as those in the P-town sample after being infected, then why do we all have to cover up?

Why can’t we just ask people with symptoms to stay home?

The key element of the study:

The “cycle threshold” refers to the number of cycles that a PCR machine must perform on a given viral sample before detecting viral RNA. The fewer cycles required, the more likely the virus is in that particular sample. This means that lower Ct values ​​should indicate a higher viral load, which in turn could indicate greater infectivity. In the Provincetown study, the Ct values ​​in vaxxed and unvaxxed were similar. In this study, the values ​​are lower in unvaxxed than in vaxxed. Which means that the two groups are not equally infectious, assuming Ct values ​​are a reliable indicator of infectivity. (A debatable hypothesis!) The unvaccinated should be more contagious.

The hard numbers:

It’s a big, big sample, Silver points out, much larger than the one in Provincetown that the CDC relied on, which means the margin of error in the data here is much smaller. As you can see, people who received zero doses of the vaccine had consistently lower Ct values ​​than people who received one or two, meaning they likely had higher viral loads on average. . In the form of a graph:

If the British study is correct, it is not necessarily true that the vaccinated are as infectious as the unvaccinated, which was the key finding behind the CDC’s new mask recommendations. At best, the data is divided and, due to its methodological superiority, the UK study should be considered more reliable than those from Provincetown or Wisconsin.

But even so, I would like two questions answered:

1. Although vaccinated people may have lower viral loads on average than unvaccinated people in UK data, are these still high enough that it is fair to assume they are infectious? The figures above show that both groups consistently had less than 30 Ct values. In the Wisconsin study published last week, the authors noted that “Previous studies have suggested that Ct values ​​of around 30 or less are compatible with the recovery of infectious virus from biological samples, an indication of potential contagiousness. ” If this is true, then many vaccinated, even in the UK study, could have been contagious to others, if not as contagious as the unvaccinated. Which would mean that the CDC’s conclusion that it’s worth having the vaxxed mask would have some merit after all.

2. The table above shows no significant difference in Ct values ​​between people who received one dose of the vaccine and people who received two, a bewildering result given all the hype about how one dose. dose of the vaccine does not protect you much from Delta. It is only after two doses that you have strong immunity. Why do single feeders see similar Ct values ​​to dual feeders? The best I can do with a theory is behavioral. Because the monodoses knew they were not yet protected from Delta, they crouched down after their first shot; the two-dosers, knowing they had top-notch immunity, went out and partied and ended up being exposed to more viruses on average.

While we talk about the UK, you’ll be happy to know that their decline in Delta cases has continued since we last wrote about it, although it has leveled off of late. Hospitalizations are now also down:

Scientists continue to debate whether this is a lasting remission due to increasing herd immunity or an oddity due to an amalgam of factors, such as children suddenly out of school, with the Euro 2020 tournament over and hundreds of thousands of people self-isolating due to exposure to someone who is infected. (“However, Paget warns that there are indications that infections may now rise again.”) The only unfortunate issue is that deaths here will likely rise a little more sharply than there because the UK has a much higher percentage of fully vaccinated seniors than us. Britain didn’t come close to setting a new pandemic-era hospitalization record in its latest wave, but some places here did. I leave you with this:



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