Peter wrote:
According to this the vaccines do not fully protect against one of the Indian variants.
Many considerations on this:
- No vaccine does “fully protect”. There are many reasons, why even a fully vaccinated person can still get the disease. Most of these reasons …
- … particularly apply to care home inhabitants (weak immune system, high succesptability to any kind of disease, many comorbidities, many co medications, etc.)
- The “outbreak” according to the press report was a week after second shot with AZ. According to the label, AZ is only fully effective 2 weeks after second shot. Therefore it is not surprising that vaccination is not fully effective even without blaming some “Indian variants”.
It actually sounds a bit weird that UK was first celebrating its vaccination strategy “don’t care too much about the second shot as the first shot also gives us 50-70% protection” and now seems to be surprised that “gee, those people with one shot are only 50-70% protected”.
I don’t think that in Germany there is still a care home where inhabitants are not clearly more than 2 weeks after second shot.
that UK was first celebrating its vaccination strategy “don’t care too much about the second shot as the first shot also gives us 50-70% protection” and now seems to be surprised that “gee, those people with one shot are only 50-70% protected”.
From the public policy POV, the 1st shot (of PF or AZ – they are both the same in effect) does the job in that it greatly reduces the hospital loading, to the point where the numbers are hardly noticed against the background load. That is a huge success by any measure.
For getting infections really down, for stuff like travel and resistance to new strains, you no doubt need both doses.
Malibuflyer wrote:
It actually sounds a bit weird that UK was first celebrating its vaccination strategy “don’t care too much about the second shot as the first shot also gives us 50-70% protection” and now seems to be surprised that “gee, those people with one shot are only 50-70% protected”.
I believe the thinking behind going all-out on first shots was that any significant efficacy, even 50-70%, in a critical mass of the population will enormously restrict transmission to the point that R simply cannot get above 1 – and the effect on infection rates has shown this to be the case. They worked out that if you only have X doses and you want to reduce infections/deaths, it is better that Y people get one dose than 0.5Y get two doses. In any case, once the infection rates are down in the noise (which they are in the UK now) it doesn’t matter for an individual if they only have 50-70% protection because they are PROB99.99 not going to come into contact with the virus anyway.
We presently have ~2/3 of the adult population (35m) having had one jab and ~1/3 (16m) having had both jabs, and this really cripples the ability of the virus to spread because when an infected person is ‘trying’ to spread the virus some very significant % of the people they come into contact with are non-viable hosts. Even a year ago when it was really accelerating infected people generally only spread it to 1-3 others, so once you use vaccines to knock that number in half (or less) the outcome is obvious.
Good point from @gallois about good scientists never committing 100%. The media and the general public will never really understand this, but all we knew pre-Covid about viruses and vaccines told us that PROB99 a working vaccine would have an enormous effect on transmission.
Same with the dose spacing. Saying it might not work with a longer spacing is a bit like saying your parachute might not work from 6,000ft because the manufacturer only tested it from 5,000ft, and then note that the strict manufacturer’s line of “use only the proven dosing regimen” is a position from their lawyers, not their scientists.
Note also that dose-spacing with vaccines is normally dictated primarily by operational convenience. All we know pre-Covid tells us that a longer spacing is usually more effective, but we compromise on that for convenience – you don’t want 12 weeks between yellow fever doses because it would mean that anyone wishing to travel to a yellow fever zone would need at least 12 weeks notice. A shorter time between doses also shortens the clinical trials, as you can imagine.
It took some fairly smart cookies to work out that in this unusual situation (a race against infection, wanting to jab nearly everyone, not able to produce fast enough) the conventional desire to shorten the time between doses actually led to an undesirable outcome in the real world. Credit to the guys who worked this out and issued the 12 week advice, and (some) credit to the government that was brave enough to act on it.
Peter wrote:
From the public policy POV, the 1st shot (of PF or AZ – they are both the same in effect) does the job in that it greatly reduces the hospital loading, to the point where the numbers are hardly noticed against the background load. That is a huge success by any measure.
Might well be. My point was not, that it was a generally bad decision.
It is just that outbreaks in individual care homes are therefore not a surprise but a conscious design feature of the UK approach. On average the protection might be quite high – but this is not a contradiction to individual outbreaks.
but a conscious design feature of the UK approach.
WOW, what else will be invented?
Malibuflyer wrote:
It is just that outbreaks in individual care homes are therefore not a surprise but a conscious design feature of the UK approach.
I don’t think it’s that. Your statement about everyone in a care home being double-jabbed two weeks ago is likely just as true in the UK as it is in Germany. It was back in late March that the UK switched 4/5 of its daily dosing to second doses, and now has 24% of the whole population double-dosed to Germany’s 8.5%.
I’d say it’s a combination of culturally lower compliance than Germany (we say all care home residents, but we know that some small number can/will refuse and/or are contraindicated) and close ties to India with much travel and mixing.
Graham wrote:
Saying it might not work with a longer spacing is a bit like saying your parachute might not work from 6,000ft because the manufacturer only tested it from 5,000ft, and then note that the strict manufacturer’s line of “use only the proven dosing regimen” is a position from their lawyers, not their scientists.
Dose spacing in vaccines is much more difficult than that. Depends heavily on the acting mechanism, the specific vaccine and disease, etc.
It is actually quite comparable to the parachute: Cirrus also tells you, that you should pull the chute early enough before your airspeed in the fall exceeds 140kt. That doesn’t mean that it can never work beyond 140kt but it is better to do it before.
Graham wrote:
you don’t want 12 weeks between yellow fever doses because it would mean that anyone wishing to travel to a yellow fever zone would need at least 12 weeks notice.
yellow fever is one shot in lifetime – used to be one shot every 10 years …
Malibuflyer wrote:
yellow fever is one shot in lifetime – used to be one shot every 10 years …
My apologies – I picked the first travel vaccine that came to mind without researching it. Hep B or Japanese encephalitis vaccines would be examples of the point I’m making.
The point is no-one with any education in the subject seriously believed there was any reason why stretching the time between doses would adversely effect efficacy. Even if it had, which would have been an incredible surprise, it would PROB90 have been worth it to achieve some protection in a greater number of people. There is a paper here from 2015 which finds that so long as you have substantial protection after a first dose then a one-dose strategy is optimal in the face of limited supply.
The spacing used in the clinical trials had to be chosen somehow. A major factor was getting the trials completed quickly, and choosing 12 weeks rather than 3 would have meant each set of interim and final results arriving 9 weeks later than they did.
Malibuflyer wrote:
Cirrus also tells you, that you should pull the chute early enough before your airspeed in the fall exceeds 140kt. That doesn’t mean that it can never work beyond 140kt but it is better to do it before.
I don’t think this compares. There is a clear and obvious scientific rationale supporting that fact that the likelihood of a successful deployment become less at speeds >140kts. They knew there was going to be an upper speed limit somewhere before they did any calculations or fired any test rigs – it is obvious to anyone with a basic understanding. For the parachute and the vaccine there is no reason anyone can suggest it won’t work, rather just a lack of proof (so far) that is does work. Absence of proof is not proof of absence, and in an emergency situation one becomes less strict about positive proof.
Graham wrote:
our statement about everyone in a care home being double-jabbed two weeks ago is likely just as true in the UK as it is in Germany.
The article Peter quoted on this issue with the Indian variant clearly states that the inhabitants of the care home where this issue came up were just a week past their second shot.
I’m just saying that in this specific case that Peter (and the article he quoted) referred to the issue is not “India” but late second shot. It has just by chance been an Indian variant of the virus.
Malibuflyer wrote:
That is – unfortunately – a common misunderstanding based on early press reports of journalists that have little clue about clinical trials but therefore an even stronger opinion.
As this is what governments base their decisions on, it better be rectified by someone who is ready to take responsibility and also has the clout to do it so that governments will reckognize it and implement it.
