5 ms·

Stupid question, could this come down to the volume of the shot? I understand Moderna is ~3x as much as pfizer volume wise, otherwise I thought the method of ac

Stupid question, could this come down to the volume of the shot? I understand Moderna is ~3x as much as pfizer volume wise, otherwise I thought the method of action is roughly the same.

Robotbeat 5y ago
Indeed. To some extent, we can use pretty basic principles like the Law of Mass Action (https://en.wikipedia.org/wiki/Law_of_mass_action https://en.wikipedia.org/wiki/Law_of_mass_action "In chemistry, the law of mass action is the proposition that the rate of the chemical reaction is directly proportional to the product of the activities or concentrations of the reactants.") to inform our priors on this. We should expect the Moderna one to be both somewhat more effective and have somewhat worse side effects simply due to the higher dose and similar action.
- userbinator 5y ago
  The other question is whether Moderna will also last approximately 3x as long as Pfizer, or if it's a far more nonlinear curve.
  - Robotbeat 5y ago
    I’m sure it’s nonlinear to some extent as the immune system is complex. But you’d be surprised if there was zero effect of more dose.
bryan0 5y ago
Not stupid at all. Yes this is the main theory as to why moderna wanes less than pfizer. https://www.businessinsider.com/pfizer-lower-dose-moderna-covid-19-vaccine-fewer-side-effects-2021-9 https://www.businessinsider.com/pfizer-lower-dose-moderna-co...
- Gibbon1 5y ago
  Other theory is Moderna has 4 weeks between doses vs 3 for Pfizer.
  - version_five 5y ago
    This is interesting. In canada we had a longer waiting time between the shots because of lack of supply. People who got it earliest (older, etc) generally had a 12 week waiting time I think though it may have been shortened as we got more supply. I got my first (pfizer) as soon as I was eligible, and could get my second 8 weeks later. I think people that got their first shot later could wait a much shorter time, i.e. the recommended 3/4 weeks. It would be interesting to see if its possible to disentangle the effects of the way they were rolled out in different countries to see how much of a difference timing makes.
  - 1cvmask 5y ago
    And that Pfizer was supposedly given to older people (weaker immune system) versus the others. Would be good to have adjusted studies.
    - bryan0 5y ago
      This is interesting. Do you have a source for this?
      - dboreham 5y ago
        Not a source but around here Pfizer was available first so the most at risk people got it.
  - mensetmanusman 5y ago
    This shouldn’t be downvoted, they are finding that waiting between the two doses longer does help.
    - tux3 5y ago
      There are broader points to be made about the voting system on HN, and the efficiency with which we're sorting information. It bothers me how little conscious time we spend improving the mechanisms of the places we discuss in. If the sorting system were a little better at avoiding good comments being downvoted, when they are pointing out something not immediately obvious and agreeable, that would elevate the efficiency of discourse. That seems more valuable than the time that has been spent on it would seem to indicate.
ayngg 5y ago
Among other differences, Moderna dosages had ~3x more mRNA compared to Pfizer (100 v 30 micrograms), and their regime had longer periods between dosages. Apparently rationale for Pfizer doses was to minimize side effects because from their initial testing they did not find a significant increase in antibodies with a higher dosage [1]. [1] https://www.nejm.org/doi/full/10.1056/NEJMoa2027906 https://www.nejm.org/doi/full/10.1056/NEJMoa2027906

Stupid question, could this come down to the volume of the shot? I understand Moderna is ~3x as much as pfizer volume wise, otherwise I thought the method of action is roughly the same.

Robotbeat 5y ago

Indeed. To some extent, we can use pretty basic principles like the Law of Mass Action (https://en.wikipedia.org/wiki/Law_of_mass_action https://en.wikipedia.org/wiki/Law_of_mass_action "In chemistry, the law of mass action is the proposition that the rate of the chemical reaction is directly proportional to the product of the activities or concentrations of the reactants.") to inform our priors on this. We should expect the Moderna one to be both somewhat more effective and have somewhat worse side effects simply due to the higher dose and similar action.

userbinator 5y ago
The other question is whether Moderna will also last approximately 3x as long as Pfizer, or if it's a far more nonlinear curve.
- Robotbeat 5y ago
  I’m sure it’s nonlinear to some extent as the immune system is complex. But you’d be surprised if there was zero effect of more dose.

bryan0 5y ago

Not stupid at all. Yes this is the main theory as to why moderna wanes less than pfizer. https://www.businessinsider.com/pfizer-lower-dose-moderna-covid-19-vaccine-fewer-side-effects-2021-9 https://www.businessinsider.com/pfizer-lower-dose-moderna-co...

Gibbon1 5y ago
Other theory is Moderna has 4 weeks between doses vs 3 for Pfizer.
- version_five 5y ago
  This is interesting. In canada we had a longer waiting time between the shots because of lack of supply. People who got it earliest (older, etc) generally had a 12 week waiting time I think though it may have been shortened as we got more supply. I got my first (pfizer) as soon as I was eligible, and could get my second 8 weeks later. I think people that got their first shot later could wait a much shorter time, i.e. the recommended 3/4 weeks. It would be interesting to see if its possible to disentangle the effects of the way they were rolled out in different countries to see how much of a difference timing makes.
- 1cvmask 5y ago
  And that Pfizer was supposedly given to older people (weaker immune system) versus the others. Would be good to have adjusted studies.
  - bryan0 5y ago
    This is interesting. Do you have a source for this?
    - dboreham 5y ago
      Not a source but around here Pfizer was available first so the most at risk people got it.
- mensetmanusman 5y ago
  This shouldn’t be downvoted, they are finding that waiting between the two doses longer does help.
  - tux3 5y ago
    There are broader points to be made about the voting system on HN, and the efficiency with which we're sorting information. It bothers me how little conscious time we spend improving the mechanisms of the places we discuss in. If the sorting system were a little better at avoiding good comments being downvoted, when they are pointing out something not immediately obvious and agreeable, that would elevate the efficiency of discourse. That seems more valuable than the time that has been spent on it would seem to indicate.

ayngg 5y ago

Among other differences, Moderna dosages had ~3x more mRNA compared to Pfizer (100 v 30 micrograms), and their regime had longer periods between dosages. Apparently rationale for Pfizer doses was to minimize side effects because from their initial testing they did not find a significant increase in antibodies with a higher dosage [1]. [1] https://www.nejm.org/doi/full/10.1056/NEJMoa2027906 https://www.nejm.org/doi/full/10.1056/NEJMoa2027906