5 ms·

It's interesting to layman's eyes that the dosing regime using 1.5 doses is more effective than the one using 2 doses as I would expect the inverse; are there a

It's interesting to layman's eyes that the dosing regime using 1.5 doses is more effective than the one using 2 doses as I would expect the inverse; are there any plausible explanations for this?

sanxiyn 6y ago
One possibility is that 1.5 dosing regime reduces unwanted immune reaction against vector (not payload). Pfizer and Moderna vaccines are not vectored.
codeulike 6y ago
These stats are based on 130 people getting covid out of an experiment of 25,000 people. They dont give a breakdown of the stats (e.g. who was on placebo, who was on which dosing regimen ) but those are small nubmers. I think its possible that this is just noise. The difference between '60%' and '90%' might just be a handful of cases. They show that it works though, thats the main thing. edit: e.g. of those 130 cases lets assume half were in each regimen experiment. So 65 cases in the 'two full doses experiment' if they got 60% efficiacy then that means about 26 people with the vaccine got covid vs 39 with placebo. In the 'half dose then full dose' experiment if they got 90% efficacy then that means about 7 people with the vaccine got covid vs 58 with placebo. So the difference between 60% and 90% is 19 people. They show that the vaccine works but there is lots of uncertainty between the two dosing regimens. Edit: why the downvotes?
- GhostVII 6y ago
  Only 2700 people were in the 1.5 dose variant.
  - deleted 6y ago
    [deleted]
- haltingproblem 6y ago
  +Gold for the numerical workout :)
cuchoi 6y ago
This comment seems like a reasonable hypothesis: https://news.ycombinator.com/item?id=25184877 https://news.ycombinator.com/item?id=25184877
bart_spoon 6y ago
One theory is that it's due to the vector. This utilizes an adenovirus (which has been used more commonly in vaccines previously, and is different from the novel mRNA viruses developed by Biontech/Pfizer/Moderna). The thought process is that with a larger initial dose of the vaccine, more immune resistance is built up by the body initially, which then neutralizes some of the booster when its given later.
thehappypm 6y ago
It's because of the way the AZ vaccine works. It uses a different virus to infect cells which then create the antigen to stimulate the immune response. These are a bit unstable, since the vaccine itself, being a virus, is an immune system trigger. The immune system might snuff out the vaccine itself after a huge first dose, then the second dose is wiped out. This is I think why the mRNA vaccines are doing better. They don't use a virus as a vector, they use a less convoluted vector of a more basic mRNA instruction set. They're also in a way more "scalable" in that a future disease or a mutation of Covid with a new spike protein could have a new vaccine made quickly by tweaking the mRNA sequence.

It's interesting to layman's eyes that the dosing regime using 1.5 doses is more effective than the one using 2 doses as I would expect the inverse; are there any plausible explanations for this?

sanxiyn 6y ago

One possibility is that 1.5 dosing regime reduces unwanted immune reaction against vector (not payload). Pfizer and Moderna vaccines are not vectored.

codeulike 6y ago

These stats are based on 130 people getting covid out of an experiment of 25,000 people. They dont give a breakdown of the stats (e.g. who was on placebo, who was on which dosing regimen ) but those are small nubmers. I think its possible that this is just noise. The difference between '60%' and '90%' might just be a handful of cases. They show that it works though, thats the main thing. edit: e.g. of those 130 cases lets assume half were in each regimen experiment. So 65 cases in the 'two full doses experiment' if they got 60% efficiacy then that means about 26 people with the vaccine got covid vs 39 with placebo. In the 'half dose then full dose' experiment if they got 90% efficacy then that means about 7 people with the vaccine got covid vs 58 with placebo. So the difference between 60% and 90% is 19 people. They show that the vaccine works but there is lots of uncertainty between the two dosing regimens. Edit: why the downvotes?

GhostVII 6y ago
Only 2700 people were in the 1.5 dose variant.
- deleted 6y ago
  [deleted]
haltingproblem 6y ago
+Gold for the numerical workout :)

cuchoi 6y ago

This comment seems like a reasonable hypothesis: https://news.ycombinator.com/item?id=25184877 https://news.ycombinator.com/item?id=25184877

bart_spoon 6y ago

One theory is that it's due to the vector. This utilizes an adenovirus (which has been used more commonly in vaccines previously, and is different from the novel mRNA viruses developed by Biontech/Pfizer/Moderna). The thought process is that with a larger initial dose of the vaccine, more immune resistance is built up by the body initially, which then neutralizes some of the booster when its given later.

thehappypm 6y ago

It's because of the way the AZ vaccine works. It uses a different virus to infect cells which then create the antigen to stimulate the immune response. These are a bit unstable, since the vaccine itself, being a virus, is an immune system trigger. The immune system might snuff out the vaccine itself after a huge first dose, then the second dose is wiped out. This is I think why the mRNA vaccines are doing better. They don't use a virus as a vector, they use a less convoluted vector of a more basic mRNA instruction set. They're also in a way more "scalable" in that a future disease or a mutation of Covid with a new spike protein could have a new vaccine made quickly by tweaking the mRNA sequence.