A new study out of Harvard offers evidence that SARS-CoV-2 variant B.1.1.7’s increased transmissibility isn’t due to its viral load but rather it’s delayed clearance, resulting in longer duration of infection. The implications are extremely positive. 🧵 dash.harvard.edu/bitstream/hand…
This could potentially mean a longer personal isolation period (longer than the currently recommended 10 days after symptom onset) may be all that is needed to control the spread of B.1.1.7!
For individuals infected with B.1.1.7, the mean duration of the proliferation phase was 5.3 days, the mean duration of the clearance phase was 8.0 days, and the mean overall duration of infection (proliferation plus clearance) was 13.3 days.
These compare to a mean proliferation phase of 2.0 days, a mean clearance phase of 6.2 days, and a mean duration of infection of 8.2 days for non-B.1.1.7 virus. More studies will need to be performed of course but this could mean a lot going forward as to how to handle B.1.1.7.
When I say “clearance” I am referring to how long it takes for the infection to naturally clear from the body. An individual is infectious for a longer period of time with B.1.1.7. This could mean all that’s needed is 13-14 days quarantine instead of 10 for the infection to pass.
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This is extremely promising. A new study conducted by Pfizer and Israel’s Health Ministry shows Pfizer’s vaccine was estimated to be 89.5% effective at preventing SARS-CoV-2 infections regardless of whether symptomatic or not. This infers a possible reduction in transmission! 🧵
Study is based on real-world data and analysis of individuals vaccinated with their 2nd dose.
90% Drop in infection
Effectiveness:
94% against symptomatic infection
94% against severe/crit. hospitalization
93% against death
This study can be found here (just see the screens).
The next two studies I want to highlight take into account viral load. When an infected individual has a high viral load, they are more likely to shed more viral particles, hence transmit the virus. Higher viral load is usually associated with severe disease as well. Carrying on.
Lab studies suggest Pfizer’s and Moderna’s vaccines CAN protect against SARS-CoV-2 variants B.1.351 and B.1.1.7. Despite reduction, neutralizing titer levels with B.1.351 remain above levels that are expected to be protective! cnn.com/2021/02/17/hea…
In addition, they found NO reduction in efficacy against the B.1.1.7 variant! It’s a good day!
Preliminary reports can be found here:
Pfizer: nejm.org/doi/full/10.10…
Moderna: nejm.org/doi/full/10.10…
Wanted to share more this morning concerning safety and efficacy of these vaccines that might put some of you with delayed Pfizer doses at ease. One dose of Pfizer’s vaccine was found to be highly efficacious, with a vaccine efficacy of 92.6%, similar to the first-dose efficacy
I want to bring this up. I’m sure by now you have seen those sensationalist headlines about variants merging and “heavily mutated hybrids” and what not. Guess what I want you to do right now? Ignore them. Yes, ignore them. Know why? Things like this are just mass hysteria.
The ones we need to be paying attention to are B.1.1.7, B.1.351 and P.1 because these are the only known SARS-CoV-2 variants that HAVE been shown to possess any evidence of functional significance or biological properties that make them a cause for concern to date. The rest?
Forget them. I read one article and I quote: “the recombination event may have occurred within the sample after it was taken from the infected person, not while it was inside their body. In which case it is an accidental laboratory artefact, not a wild virus.” Makes my head hurt.
Let’s discuss SARS-CoV-2 variants, selective pressure, and mutations. In the face of variants, our best protection is to get more people vaccinated. Vaccination will not automatically select for vaccine-resistant variants, especially if we can reduce transmission. Here’s why. 🧵
First, it is important to realize these vaccines will not drive the emergence of new variants and compel this virus to mutate in novel ways (OR create some scary super mutant so throw that idea out the window). I think this where a lot of the confusion lies- it’s not possible.
The specific mutations we are currently witnessing focus on altering the fitness of this virus by improving its rate of transmission with some signs of immune evasion. Mutation is a fairly constant process to begin with. It occurs randomly when a virus replicates and trust me,
That’s not how this works.
That’s not how any of this works.
Viruses need one thing to mutate: a host. Protect the host, stop the mutations. We REALLY need to stop giving these people platforms when it’s blatantly obvious they have no idea what they’re freaking talking about.
For those asking what the issue is. This is a VERY misguiding message. Let me put it this way because no one is stating such even though they should be: it is FAR less likely for variants to occur in a vaccinated population than an unvaccinated population. Why? To put it simply:
This is basic virology. This virus isn’t exhibiting stress-induced mutagenesis. It is adapting solely to increase its fitness and that’s what it is selecting its mutations for- it isn’t adaptive immune pressure. This is happening only due to the fact it is infecting more people.
Certain “experts” should be quite ashamed for pushing fear mongering tweets and using misleading studies to fit their rhetoric concerning the efficacy of these vaccines. Since they rely on the fact most will not understand the studies since it’s not in layman’s terms allow me. 🧵
Firstly, the conclusions being drawn from this study and this “expert” is that the B.1.1.7 and B.1.351 variants would render these vaccines ineffective. This is highly unlikely. It will take a large amount of genetic diversity to completely render the current vaccines useless.
Not to mention Ding is using an older study to push this rhetoric when Pfizer and Moderna have recently established their vaccines will be effective against these variants. Perhaps someone should pass THOSE studies onto him. For the record, if you’re going to claim these vaccines