It’s saying that the second Pfizer dose only gives a marginal improvement on efficacy as the first dose is already over 90%. The first dose giving most of the efficacy is true for all the vaccines currently available (although AZ is much lower than 90%…is it around 50%?), the first dose provides most of the protection, the second one is the booster. The main advantage of the second dose though, for both Pfizer and AZ, is it gives a longer-term immunity.
It really does look like the smart play is to get as many people the first dose as quickly as possible. I would expect other countries to start following suit pretty quickly.
One thing that’s really important to understand is what is meant by efficacy? I hadn’t appreciated until a few days ago, that it is the following:
95% efficacy doesn’t mean that if you get vaccinated you’ve still got a 5% chance of catching covid. It is the comparison between those who got symptomatic cases of covid in the vaccinated group compared with the unvaccinated control group. So in Pfizer, 8 of those in the vaccinated group developed covid symptoms compared with 162 in the unvaccinated group. However, the reality is that just 0.04% of the vaccinated group got infected with covid.
Maybe it was just me that misunderstood this point?
I didn’t think we knew how "longer term"the immunity given was.
Does the Pfizer vaccine give better immunity after 1 dose than AZ and the some others do after 2 doses.If yes then,other than cost,wouldn’t that be they way to go while supplies are low.
If the same checks are done on AZ and other vaccines from 2 weeks after initial dose,have they found similar increase in efficacy.
Yes, I think the Pfizer dose gives better efficacy after one dose than AZ does after 2 but the immunity is not expected to last as long (I think that is the assumption at the beginning and there may now be data to support that? Not sure).
One of the issues is that there has been production issues with Pfizer as well so they are also falling short, currently. This was intentional by Pfizer because they refitted their factories to ensure that their production could increase going forward (I think they expect to start hitting higher rates of production next month?).
AZ efficacy has already been shown to improve to a sweet spot of between 8-12 weeks from first jab, with no drop off in that period (hence justifying the government’s decision to extend the interval between first and second jabs).
Cost is certainly an issue with the Pfizer jab though, you’re right. It’s considerably more expensive than the AZ one. There’s definitely an argument that the richer nations should concentrate on Pfizer, Moderna and Jansen (etc) and the developing countries be given almost exclusive access to AZ.
Yes, I did that back in October. Just a finger prick test, right? Results known in less than 15 minutes and something you can do at home.
That’s for antibodies though, it doesn’t test as to whether you are currently infectious which is the tests that are needed for a sustained return of children to school. I’m not sure what home-testing kits are available other than the oral/nasal swabs that you then need to send off anyway? Are there any at home testing kits for being infectious that you can get the result for yourself, at home?
These are the reasons i’m asking about weather or not we can,for now,use 1 dose of Pfizer.It will go twice as far at the same price in the same time period,freeing up the AZ for poorer/less developed counties at the same time.This would hopefully mean the world over is protected quicker and at the same time as each other, keeping the chances of more variants developing down(hopefully) and maybe largely ridding ourselves of the virus rather than having to get yearly boosters.
That depends. If you want to keep going at the current rate (approximately 400k/day in the UK) then the answer is no. There’s not enough Pfizer doses in production currently to supply the UK at that rate (and also those ordered by other countries). However, from the end of March there almost certainly will be and the UK has ordered 40 million Pfizer doses (so enough for 20 million people to complete a 2-dose regimen). I estimate it’s administered about 10 million Pfizer doses so far. It hasn’t yet ordered any more than that though. It is expecting to receive 17 million Moderna doses too though, I think by the end of March.
We have to be careful here imo. Reduction in symptoms is not immunity and is not efficacity.
The Pfizer vaccine is the most efficace vaccine approved but to get to levels of anti bodies of someone who has actually had covid needs 2 doses.
UK are taking a risk, where the calculation is impossible so based on intuition I suppose, in delaying the 2nd dose. In effect vaccinated with 1 dose means you still get (and don’t fight efficacely) the infection. This means they walk around with reduced risk to themselves but not to others. Also they become incubateurs for mutations and new variants.
The thing is that the efficacity of vaccines is probably due mainly to the adjuvants incorporated. Pfizer gets more ‘allergic’ type reactions, 1 in 200, though in general these are very mild due to the adjuvants they incorporate in the shot (another discussion).
So is it really cost effective to only give 1 shot? I doubt it in the long term short term definitely. Comes down to a political gamble in the end on what possible outcomes and what information on those outcomes is. Who knows?
I did some googling and I see that for the NHS they’ve been making rapid lateral-flow testing kits available to their primary care staff since December. This is an anti-gen test so picks up whether you are currently covid infectious (to a very high degree of accuracy [98%+]). This has helped the NHS manage the crisis within their hospitals. https://www.ouh.nhs.uk/working-for-us/staff/covid-staff-faqs-home-testing.aspx
Came across something of interest yesterday. My better hall’s sister works in a care home. The staff all received jabs 3 weeks ago. Of the 12 or so staff 6 have now tested positive.
That’s interesting. I wonder if the test is picking up the trace of the vaccine? Also, the important point is that it takes about 10 days for the vaccine to become effective so I wonder how soon after they were vaccinated did they become infected (if indeed the positive test is due to becoming infected rather than the vaccine itself).
Yes, that would have been my first assumption. I thought you weren’t supposed to have tests after having the vaccine (although I guess that may only apply for a specific window).
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