5 ms·

> In fact, it's far from clear Seems clear from my perspective. Two doses are recommend by manufacturers. Anything more or less is pure speculation at best. Wh

> In fact, it's far from clear Seems clear from my perspective. Two doses are recommend by manufacturers. Anything more or less is pure speculation at best. Why speculate in absence of a way to test your hypothesis?

lisper 6y ago
Because the manufacturer recommendations are based on achieving the best outcome for the individual receiving the treatment. But we're in a global pandemic, a situation the world has not faced in living memory. A different quality metric might be appropriate under these circumstances.
- mns 6y ago
  So even though the manufacturers (the companies that developed the vaccines, the scientists, the people running the trials, the ones that know the data and went through a full year of tests) keep on recommending 2 doses and the advice given to the UK government was still to stick to the 2 doses, we're now going the way that "we think we know better and it's better to try something new and untested because it's a pandemic and it might be better to have less efficiency to more people, than full efficiency to less people", even though it's, again, not tested and a shot in the dark?
jjeaff 6y ago
Was there any testing done comparing 2 doses to one? I think it was speculation that led us to test with 2 doses because we'll, we don't have much time, 2 must be better than one.
- lisper 6y ago
  https://www.wbur.org/commonhealth/2020/12/18/coronavirus-vaccine-single-dose-debate https://www.wbur.org/commonhealth/2020/12/18/coronavirus-vac...
freeone3000 6y ago
The study we have of a two-dose COVID-19 vaccine with one dose administered showed 67% effectiveness, in line with vaccines for other diseases (including eradicated ones - polio vaccine is 80%).
BurningFrog 6y ago
The manufacturer doesn't know anything about this that isn't public information. Yes, two doses are almost certainly better than one. But those are not the choices. When there are far fewer doses than the number of people to vaccinate, the question is if it's better to give N people 2 shots, or 2N people 1 shot. The test data looks like 1 dose gives ~80% protection vs ~95% for 2 doses. The 2x80% scenario is clearly better than 1x95%. And, of course, everyone would get the second dose as soon as production catches up.
- pavelrub 6y ago
  The main unknowns aren't around short-term efficacy, but long term immunity. If it turns out that a single dose provides ~80% protection but only for 3 months, whereas the second dose provides strong long-term protection, the one-dose scenario would be significantly worse.
  - BurningFrog 6y ago
    Longer term, everyone gets a booster shot as soon as they're available.
    - Bootvis 6y ago
      What if it takes 9 months to have the booster shots available? People will be vulnerable for 6 then.
      - Exmoor 6y ago
        Vulnerability isn't binary. You're not immune one day and susceptible the next. It's much more likely that immunity to getting sick might start decreasing over time, but still remain relatively high. So, perhaps 80% in 3 months, 60% in 6 months, and 30% in 9 months to use made up numbers. Additionally, production is still ramping up so it's highly unlikely that we'll have less vaccine in 3 months than currently. We'll also likely have 1-3 more approved vaccines by then as well.
cltby 6y ago
> Anything more or less is pure speculation at best There are two lines of evidence. The first is empirical. It It appears that one dose of Moderna _is_ highly effective, perhaps 85% or more. Note the treatment-control divergence after about fourteen days [1]. The second is theoretical. From our ample medical experience with other vaccines, there is strong prior reason to think that one dose is likely to work well, and that a second shot in the distant future would be even better than a second shot after three or four weeks. Booster shots are given a.) as backup for people who don't seroconvert after one dose b.) to trigger a secondary immune response. In light of a.), we shouldn't be surprised by the 85% number (most people seroconvert; there's no partial immunity, you either seroconvert or you don't). In light of b.), we should be very skeptical of the four week interval, especially since the secondary response takes about two weeks to develop. It's shorter than the interval for every other vaccine. [1] https://arstechnica.com/science/2020/12/fda-releases-data-on-modernas-covid-vaccine-it-looks-good/ https://arstechnica.com/science/2020/12/fda-releases-data-on... [2] https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolescent.html https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolesc...
- Exmoor 6y ago
  Agreed. It's also important to remember that the 3/4 week dates for the second dose were not chosen based on it being the most effective timeline, but because it was the minimum time needed to complete the studies as quickly as possible. If they'd chosen 8 weeks we wouldn't have US approval yet. If they'd chosen 12 weeks we wouldn't even know if they were effective yet.

lisper 6y ago

Because the manufacturer recommendations are based on achieving the best outcome for the individual receiving the treatment. But we're in a global pandemic, a situation the world has not faced in living memory. A different quality metric might be appropriate under these circumstances.

mns 6y ago
So even though the manufacturers (the companies that developed the vaccines, the scientists, the people running the trials, the ones that know the data and went through a full year of tests) keep on recommending 2 doses and the advice given to the UK government was still to stick to the 2 doses, we're now going the way that "we think we know better and it's better to try something new and untested because it's a pandemic and it might be better to have less efficiency to more people, than full efficiency to less people", even though it's, again, not tested and a shot in the dark?

jjeaff 6y ago

Was there any testing done comparing 2 doses to one? I think it was speculation that led us to test with 2 doses because we'll, we don't have much time, 2 must be better than one.

lisper 6y ago
https://www.wbur.org/commonhealth/2020/12/18/coronavirus-vaccine-single-dose-debate https://www.wbur.org/commonhealth/2020/12/18/coronavirus-vac...

freeone3000 6y ago

The study we have of a two-dose COVID-19 vaccine with one dose administered showed 67% effectiveness, in line with vaccines for other diseases (including eradicated ones - polio vaccine is 80%).

BurningFrog 6y ago

The manufacturer doesn't know anything about this that isn't public information. Yes, two doses are almost certainly better than one. But those are not the choices. When there are far fewer doses than the number of people to vaccinate, the question is if it's better to give N people 2 shots, or 2N people 1 shot. The test data looks like 1 dose gives ~80% protection vs ~95% for 2 doses. The 2x80% scenario is clearly better than 1x95%. And, of course, everyone would get the second dose as soon as production catches up.

pavelrub 6y ago
The main unknowns aren't around short-term efficacy, but long term immunity. If it turns out that a single dose provides ~80% protection but only for 3 months, whereas the second dose provides strong long-term protection, the one-dose scenario would be significantly worse.
- BurningFrog 6y ago
  Longer term, everyone gets a booster shot as soon as they're available.
  - Bootvis 6y ago
    What if it takes 9 months to have the booster shots available? People will be vulnerable for 6 then.
    - Exmoor 6y ago
      Vulnerability isn't binary. You're not immune one day and susceptible the next. It's much more likely that immunity to getting sick might start decreasing over time, but still remain relatively high. So, perhaps 80% in 3 months, 60% in 6 months, and 30% in 9 months to use made up numbers. Additionally, production is still ramping up so it's highly unlikely that we'll have less vaccine in 3 months than currently. We'll also likely have 1-3 more approved vaccines by then as well.

cltby 6y ago

> Anything more or less is pure speculation at best There are two lines of evidence. The first is empirical. It It appears that one dose of Moderna _is_ highly effective, perhaps 85% or more. Note the treatment-control divergence after about fourteen days [1]. The second is theoretical. From our ample medical experience with other vaccines, there is strong prior reason to think that one dose is likely to work well, and that a second shot in the distant future would be even better than a second shot after three or four weeks. Booster shots are given a.) as backup for people who don't seroconvert after one dose b.) to trigger a secondary immune response. In light of a.), we shouldn't be surprised by the 85% number (most people seroconvert; there's no partial immunity, you either seroconvert or you don't). In light of b.), we should be very skeptical of the four week interval, especially since the secondary response takes about two weeks to develop. It's shorter than the interval for every other vaccine. [1] https://arstechnica.com/science/2020/12/fda-releases-data-on-modernas-covid-vaccine-it-looks-good/ https://arstechnica.com/science/2020/12/fda-releases-data-on... [2] https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolescent.html https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolesc...

Exmoor 6y ago
Agreed. It's also important to remember that the 3/4 week dates for the second dose were not chosen based on it being the most effective timeline, but because it was the minimum time needed to complete the studies as quickly as possible. If they'd chosen 8 weeks we wouldn't have US approval yet. If they'd chosen 12 weeks we wouldn't even know if they were effective yet.