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Can anyone point to an explanation of how much the 60% Oxford vaccine will help things, both in the old case and in light of the new variant? I have approximate

by nmca 6y ago

Can anyone point to an explanation of how much the 60% Oxford vaccine will help things, both in the old case and in light of the new variant? I have approximately 0% intuition for how much a 60% vaccine helps.

oxfordmale 6y ago
The Oxford vaccine might only be 60% effective preventing COVID infections, howver, it is much more effective in reducing hospitalisation and deaths. Contracting flu is a bummer, but a minor inconvenience when compared to dying.
- nmca 6y ago
  Can you provide citations for this (first sentence)? My understanding is that there were no deaths in the treatment arm of the trial. But deaths are much rarer than infections so naively our uncertainty on this effect should be much larger than uncertainty about 60% infection rate reduction. Secondly, even if true, does this mean full restrictions until all are vaccinated?
  - oxfordmale 6y ago
    https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32661-1/fulltext https://www.thelancet.com/journals/lancet/article/PIIS0140-6...
    - nmca 6y ago
      Thanks - I re-read this. There was one death in the control arm, which was one of two severe cases (table 5). No statistical analysis is presented of those results (if they were significant under any straightforward model I suspect it would have been mentioned) I think it's too early to claim that there is strong evidence that the Oxford vaccine reduces cases of severe covid.
jey 6y ago
The underlying question is how much of the population has to be immune for "herd immunity" to take effect. The pandemic will burn out once enough people (let's say X% of the population) are immune to the virus, and this is called "herd immunity". Let's take the UK as our population. If a vaccine is 60% effective and we administer it to everyone in the UK, then about 60% of the UK's population will gain immunity to COVID. Another Y% of the population will have immunity to COVID already, even if the vaccine didn't work for them. Then the question is, is Y + 60 > X, thereby achieving herd immunity? You can see that if a vaccine is 95% effective, it's more likely to be above the herd immunity threshold of X%. Current estimates for X are about 70%.
- nmca 6y ago
  Ignoring herd immunity, there is also a reduction in mortality rate as older people are vaccinated. Do you have any sense which of the two effects dominates, and any citation for the 70% number? Thanks for the response :)
hedora 6y ago
Oxford measured differently than the 90% mRNA vaccines. In particular, the 60% was based on testing for asymptomatic cases, and 90% was not. The three vaccines work on similar principles. I’ll assume they are all the same. So, expect them to cut symptomatic cases by 90% among people that get the vaccine, and to add up to (60% * the percentage of people that get the vaccine) to the herd immunity progress bar. The vaccines will likely cut total deaths by less than 90%, because vaccines tend to be less effective on more vulnerable people, and of course, less than 100% of the population will get it on time. We could get lucky, and they could cut deaths of immunized people by more than 90%; no one knows yet. However the dosing screw up in the Oxford study inadvertently showed it is much less effective on old people. The new variant speeds up the clock, which means more people will catch COVID before receiving the vaccine. It’s an exponential curve, so if the current R value is 1 (optimistic), and with new lockdowns and the new variant it’s 1.7 (taking the doomsday “add 0.7” from the headline), then cases will increase ~1.7x every two weeks. There are 18 two-week periods between now and fall, when Fauci says we’re likely to return to normal. 1.7^18 is ~14,000x. There have been 83M confirmed cases globally according to Johns Hopkins, 83M * 14K >> the population of the earth, so the vaccine will be rounding error if the headline and Fauci’s warnings are correct. (It will allow frontline health workers to keep working, but that’s about it, and the hospitals will still be overrun). If we assume the roll out takes 6 months, and the new variant increases R value by 0.3 (in range according to the article), then 1.3^12 = 23x. There’s some time lag while the new virus is mostly in the UK, and more stringent measures could reduce 1.3 by a little bit. In that scenario, the vaccine will still save many people. I suspect the second scenario is more realistic.
dm319 6y ago
It's thought to be much higher than this, I think we're expecting another paper soon that shows it more comparable to pfizer/moderna. But you have to be cautious with comparisons between the trials - the control arm was different, and the follow-up was different (Oxford were swabbing weekly). The advantage of the Oxford vaccine is it can be stored at room temp. The Pfizer vaccine is largely being rolled out at large teaching hospitals - which means we can't get to the elderly and infirm, without risking exposure to them by bringing them up to the hospital. The Oxford vaccine would allow GP surgeries to give out the vaccine, as well as do home visits. I'll admit that I don't know the maths behind whether a 60% reduction (which I think would multiply R rate by 0.4) will completely mitigate the increase in R by the new variant (multiply R by 1.74). It's all about a tipping point and getting the R to stay under 1, but as I pointed out above - it's difficult to compare studies using different methodologies.
- nmca 6y ago
  Pfizer is storable at dry ice temp for ~months and regular vaccine fridge temp for 5 days [0] so whilst "large teaching hospitals" is currently accurate I don't think we're married to it. [0] https://www.pfizer.com/news/hot-topics/covid_19_vaccine_u_s_distribution_fact_sheet https://www.pfizer.com/news/hot-topics/covid_19_vaccine_u_s_...
kossTKR 6y ago
What i don't understand is that after getting Covid, you are only immune for 8-20 weeks - a few public persons have already contracted Covid twice now illustrating this. With this new variant, and the fact that we need some pretty incredible amount of people immune at once, maybe say 80%, wouldn't this mean that we need to be vaccinated 4-5 times a year? How is this feasible, even for the richest countries?
- dehrmann 6y ago
  > you are only immune for 8-20 weeks Citation needed. Last I read, it's likely much longer, and the few people are outliers.

by nmca 6y ago

oxfordmale 6y ago

The Oxford vaccine might only be 60% effective preventing COVID infections, howver, it is much more effective in reducing hospitalisation and deaths. Contracting flu is a bummer, but a minor inconvenience when compared to dying.

nmca 6y ago
Can you provide citations for this (first sentence)? My understanding is that there were no deaths in the treatment arm of the trial. But deaths are much rarer than infections so naively our uncertainty on this effect should be much larger than uncertainty about 60% infection rate reduction. Secondly, even if true, does this mean full restrictions until all are vaccinated?
- oxfordmale 6y ago
  https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32661-1/fulltext https://www.thelancet.com/journals/lancet/article/PIIS0140-6...
  - nmca 6y ago
    Thanks - I re-read this. There was one death in the control arm, which was one of two severe cases (table 5). No statistical analysis is presented of those results (if they were significant under any straightforward model I suspect it would have been mentioned) I think it's too early to claim that there is strong evidence that the Oxford vaccine reduces cases of severe covid.

jey 6y ago

The underlying question is how much of the population has to be immune for "herd immunity" to take effect. The pandemic will burn out once enough people (let's say X% of the population) are immune to the virus, and this is called "herd immunity". Let's take the UK as our population. If a vaccine is 60% effective and we administer it to everyone in the UK, then about 60% of the UK's population will gain immunity to COVID. Another Y% of the population will have immunity to COVID already, even if the vaccine didn't work for them. Then the question is, is Y + 60 > X, thereby achieving herd immunity? You can see that if a vaccine is 95% effective, it's more likely to be above the herd immunity threshold of X%. Current estimates for X are about 70%.

nmca 6y ago
Ignoring herd immunity, there is also a reduction in mortality rate as older people are vaccinated. Do you have any sense which of the two effects dominates, and any citation for the 70% number? Thanks for the response :)

hedora 6y ago

Oxford measured differently than the 90% mRNA vaccines. In particular, the 60% was based on testing for asymptomatic cases, and 90% was not. The three vaccines work on similar principles. I’ll assume they are all the same. So, expect them to cut symptomatic cases by 90% among people that get the vaccine, and to add up to (60% * the percentage of people that get the vaccine) to the herd immunity progress bar. The vaccines will likely cut total deaths by less than 90%, because vaccines tend to be less effective on more vulnerable people, and of course, less than 100% of the population will get it on time. We could get lucky, and they could cut deaths of immunized people by more than 90%; no one knows yet. However the dosing screw up in the Oxford study inadvertently showed it is much less effective on old people. The new variant speeds up the clock, which means more people will catch COVID before receiving the vaccine. It’s an exponential curve, so if the current R value is 1 (optimistic), and with new lockdowns and the new variant it’s 1.7 (taking the doomsday “add 0.7” from the headline), then cases will increase ~1.7x every two weeks. There are 18 two-week periods between now and fall, when Fauci says we’re likely to return to normal. 1.7^18 is ~14,000x. There have been 83M confirmed cases globally according to Johns Hopkins, 83M * 14K >> the population of the earth, so the vaccine will be rounding error if the headline and Fauci’s warnings are correct. (It will allow frontline health workers to keep working, but that’s about it, and the hospitals will still be overrun). If we assume the roll out takes 6 months, and the new variant increases R value by 0.3 (in range according to the article), then 1.3^12 = 23x. There’s some time lag while the new virus is mostly in the UK, and more stringent measures could reduce 1.3 by a little bit. In that scenario, the vaccine will still save many people. I suspect the second scenario is more realistic.

dm319 6y ago

It's thought to be much higher than this, I think we're expecting another paper soon that shows it more comparable to pfizer/moderna. But you have to be cautious with comparisons between the trials - the control arm was different, and the follow-up was different (Oxford were swabbing weekly). The advantage of the Oxford vaccine is it can be stored at room temp. The Pfizer vaccine is largely being rolled out at large teaching hospitals - which means we can't get to the elderly and infirm, without risking exposure to them by bringing them up to the hospital. The Oxford vaccine would allow GP surgeries to give out the vaccine, as well as do home visits. I'll admit that I don't know the maths behind whether a 60% reduction (which I think would multiply R rate by 0.4) will completely mitigate the increase in R by the new variant (multiply R by 1.74). It's all about a tipping point and getting the R to stay under 1, but as I pointed out above - it's difficult to compare studies using different methodologies.

nmca 6y ago
Pfizer is storable at dry ice temp for ~months and regular vaccine fridge temp for 5 days [0] so whilst "large teaching hospitals" is currently accurate I don't think we're married to it. [0] https://www.pfizer.com/news/hot-topics/covid_19_vaccine_u_s_distribution_fact_sheet https://www.pfizer.com/news/hot-topics/covid_19_vaccine_u_s_...

kossTKR 6y ago

What i don't understand is that after getting Covid, you are only immune for 8-20 weeks - a few public persons have already contracted Covid twice now illustrating this. With this new variant, and the fact that we need some pretty incredible amount of people immune at once, maybe say 80%, wouldn't this mean that we need to be vaccinated 4-5 times a year? How is this feasible, even for the richest countries?

dehrmann 6y ago
> you are only immune for 8-20 weeks Citation needed. Last I read, it's likely much longer, and the few people are outliers.