Nate Silver, to his credit, has been all over this one from the start. He, like so many of us, is wondering why the mainstream media has yet to give this study any airtime. They are only here to do some fear-mongering and they could not care less otherwise. These media types would rather pay closer attention to a less reputable study that the CDC is basing their new mask guidance on.
“The sample size is this non-peer-reviewed study is 79 vaccinated people (corrected, misread as 83 before) and completely lacks the statistical power to differentiate between vaccinated and unvaccinated people. Also as in the Provincetown study it’s a convenience sample, meaning people who chose to be tested, and not a random sample of all infections. That likely biases the sample toward more severe infections since people with more severe symptoms are more likely to seek out testing,” Silver tweeted.
These are obvious things to point out and it should be done by the mainstream media. Silver may have a sizable online following (3.5 million on Twitter is nothing to sneeze at) but that is nothing when compared to the reach of CNN and the like. “Another big statistical issue in these studies (at least the Wisconsin one) is that they have truncated samples. People with high Ct values (higher Ct = harder to find virus) are eliminated from the comparison because it’s not clear they can be considered “infected,” he continued.
“If one way that breakthrough infections manifest themselves is thru very low amounts of virus in some people, but then you eliminate people with very low viral loads from your comparison, you’re sort of begging the question. Need to be careful in cases like these,” Silver cautions. There’s more to the thread but you get where Nate is coming from on this one.
In other words, yes, it may be true that a symptomatic breakthrough infection will produce a viral load in a vaccinated person that is on par with the viral load in those who are not vaccinated, which could make them equally infectious to others. However, that does not tell us anything about the infectiousness of the average breakthrough infection. This mattes heavily when you stop to consider the latest CDC recommendations.
If it turns out that the average vaccinated person is nowhere near as infectious as a non vaccinated person, why are we going to all of this trouble? It seems like it would be easier to ask those who are experiencing symptoms to stay home. The cycle threshold that was discussed in the study that Silver is referencing is the key part.
This term refers to the number of cycles that a PCR machine will need to perform on a given viral sample before it detects viral RNA. The fewer cycles that are required, the less virus that is present in the sample in question. The Provincetown study claimed that the cycle threshold values were similar, while the study that Silver is urging people to consider disagrees.
Silver’s rationale is easy enough to follow. The sample size for the study he is referencing is much larger. The margin of error is a heck of a lot smaller, so the mainstream media should be leading with this. Instead, they are looking to maximize the amount of fear that is in the air right now. There are now two questions that need to be answered going forward.
While the vaccinated could have lower viral loads on average than the non vaccinated in the United Kingdom data, are they still high enough that we can assume they remain infectious? Secondly, why do those who have taken one dose of vaccine have similar values to those who have had two? Scientists will continue to debate these two topics for some time and we look forward to seeing more reputable studies. It is time for the real science to take over and for the fear-mongering crowd to sit down.