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Israel: single Pfizer injection less effective than thought


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Israel, which by now has vaccinated about 1 in 4 people (far ahead of any other country), has reported some 'real-life' preliminary data on the effect of the Pfizer vaccine after one shot. Comparing 200,000 vaccinated and a similar number of non-vaccinated persons (all over age 60) it was found there was no effect on positivity rate (positive/total tested by PCR) for the first two weeks. 'On day 14, the positivity rate dropped by 33% in the vaccinated group'. People who had received a second shot, however, had a very large increase in antibodies. These observations may be especially relevant to some countries  that have decided to postpone the second shot in order to vaccinate more people with the limited supply of doses available (like UK, who claimed that 89% efficacy was expected after one shot though I think Pfizer said it was 52%)

 https://www.theguardian.com/world/2021/jan/19/single-covid-vaccine-dose-in-israel-less-effective-than-we-hoped,     https://news.sky.com/story/covid-19-real-world-analysis-of-vaccine-in-israel-raises-questions-about-uk-strategy-12192751.

Israel has a high infection rate - with an increasing percentage due to the 'UK variant'- so it is likely that many in the vaccinated group got infected before sufficient immunity was build up. Also, in younger people, the response might be not the same. But there are unanswered questions: It is not clear what happened with the positivity rate between day 14 and 21 (presumably it stayed at 33%?) and afterwards. It is possibly too early to answer that anyway as vaccination started on December 20th. 

Edited by cormanr7
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13 minutes ago, cormanr7 said:

Israel, which by now has vaccinated about 1 in 4 people (far ahead of any other country)

 

They've only got a population of about 9 million, so easy to hit those kind of figures.

 

If the UK had the same population, they'd have vaccinated about 1 in 3.

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1 hour ago, cormanr7 said:

Israel, which by now has vaccinated about 1 in 4 people (far ahead of any other country), has reported some 'real-life' preliminary data on the effect of the Pfizer vaccine after one shot. Comparing 200,000 vaccinated and a similar number of non-vaccinated persons (all over age 60) it was found there was no effect on positivity rate (positive/total tested by PCR) for the first two weeks. 'On day 14, the positivity rate dropped by 33% in the vaccinated group'. People who had received a second shot, however, had a very large increase in antibodies. These observations may be especially relevant to some countries  that have decided to postpone the second shot in order to vaccinate more people with the limited supply of doses available (like UK, who claimed that 89% efficacy was expected after one shot though I think Pfizer said it was 52%)

 https://www.theguardian.com/world/2021/jan/19/single-covid-vaccine-dose-in-israel-less-effective-than-we-hoped,     https://news.sky.com/story/covid-19-real-world-analysis-of-vaccine-in-israel-raises-questions-about-uk-strategy-12192751.

Israel has a high infection rate - with an increasing percentage due to the 'UK variant'- so it is likely that many in the vaccinated group got infected before sufficient immunity was build up. Also, in younger people, the response might be not the same. But there are unanswered questions: It is not clear what happened with the positivity rate between day 14 and 21 (presumably it stayed at 33%?) and afterwards. It is possibly too early to answer that anyway as vaccination started on December 20th. 

 

A sudden 33% drop at day 14 sounds like a sampling effect of some sort.

 

It will also be interesting to see if efficacy against the UK B.1.1.7 is any weaker.  But B.1.1.7 is so last yearish. A bigger worry may be the Brazilian P.1 strain spreading through a population that should already have high immunity from the first wave.

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1 hour ago, rabang said:

The vaccine efficacy percentages are overhyped anyway and will cause a lot of grief and disappointment when the mass vaccinations really get underway. Any fool should understand they don't work the same in big pharma testing and in real life. Flu vaccines can have efficacy of 20 or 30 percent only. Virus mutations, massive scale of the operation etc. mean that this mess will take a long time to solve.

Agreed, but there are plenty people out there who are not aware of this or simply dismiss it and believe that by mid year everything will be cosy again. 

UK should have some data by now, but maybe they are not to keen on publishing it.

 

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3 hours ago, rabang said:

The vaccine efficacy percentages are overhyped anyway and will cause a lot of grief and disappointment when the mass vaccinations really get underway. Any fool should understand they don't work the same in big pharma testing and in real life. Flu vaccines can have efficacy of 20 or 30 percent only. Virus mutations, massive scale of the operation etc. mean that this mess will take a long time to solve.

 

In fact, the term efficacy only applies to trials anyway. It's determined by ratios of vaccinated and un-vaccinated control groups.  The term used for vaccine performance in general is 'effectiveness'.  

 

It's unlikely to be over in 6 months, the rate of infections is still climbing and significant mutations are increasing.  Another new one from Kenya today.

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16 hours ago, rabang said:

The vaccine efficacy percentages are overhyped anyway and will cause a lot of grief and disappointment when the mass vaccinations really get underway. Any fool should understand they don't work the same in big pharma testing and in real life. Flu vaccines can have efficacy of 20 or 30 percent only. Virus mutations, massive scale of the operation etc. mean that this mess will take a long time to solve.

You take the data out of context and misinterpret. it is not difficult to see if one looks at key facts;

-Flu vaccine is made using the strain that health professionals expect will appear. Sometimes the formula is not matched for the strain infecting people. Human error, not vaccine defect.

-flu vaccine is old technology and not same concept as new mRNA technology vaccine. mRNA will be more strain specific.

-2 goals of flu vaccine is to reduce the risk of flu illness overall and to reduce impact of infection if infected so person does not have to go to hospital. Depending on virus vaccinated against,40%-60% effective.

- flu vaccine is more effective against influenza B and influenza A(H1N1) viruses and less effective against  influenza A(H3N2) viruses.

 

 

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I think the problem was over-hype first started when Pfizer announced near 95% protection from infection.  I just think the definition and testing of mild infection became blurred, and it's likely that many borderline cases were missed in some trials. 

 

It also needs to be said that Pfizer has already condemned the one shot policy for its vaccine which greatly benefits from the additional dose, whereas the AZ second shot is more of a consolidation shot.

 

I've stated many times that the wrong metric was chosen anyway.  Really the only cast iron data concerns prevention of serious infection and death.  All vaccines seem to perform equally as well in this regard.

 

 

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New data from Israel, this time from health provider KSM Maccabi. Sample consisted of approx. 51,000 people, all 60+. They had been vaccinated Dec 19-24 and were followed up to day 23 (that is 2 days after the second shot). Results: both confirmed new infections and hospitalizations (smaller sample, no details) decreased by about 60%, with no effect in the first 13-14 days and then a gradual decrease to a plateau at ca.40% vs the control group. You can read the story here: https://www.dailymail.co.uk/ news/article-9179677/Israeli-healthcare-group-says-coronavirus-infections-plunged-vaccinated-60s.html

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48 minutes ago, cormanr7 said:

New data from Israel, this time from health provider KSM Maccabi. Sample consisted of approx. 51,000 people, all 60+. They had been vaccinated Dec 19-24 and were followed up to day 23 (that is 2 days after the second shot). Results: both confirmed new infections and hospitalizations (smaller sample, no details) decreased by about 60%, with no effect in the first 13-14 days and then a gradual decrease to a plateau at ca.40% vs the control group. You can read the story here: https://www.dailymail.co.uk/ news/article-9179677/Israeli-healthcare-group-says-coronavirus-infections-plunged-vaccinated-60s.html

The big take away is that Pfizer's mRNA  vaccine is excellent at stopping infections as well as reducing severe illness.

 

A few snake oil folks had been claiming Oxford's vaccine stopped infections better only because Pfizer didn't measure it! However, both types generate immunity in the same way. Thus,  mRNA vaccines' higher efficacy will stop infections better.

 

mRNA vaccines stand tall.

 

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16 minutes ago, rabas said:

The big take away is that Pfizer's mRNA  vaccine is excellent at stopping infections as well as reducing severe illness.

60% is quite a bit lower than >90% though. I think that latter figure could still be valid though:

1) IIRC the stage 3 trials used people under 60 (so in effect, Israel has conducted a trial on almost ALL of a previously more or less untested subgroup. Good idea? I think not...)

2) The 'plateau' is only apparent between days 23 & 24, and is only apparent in infections - hospitalisations dropped further, maybe as much as 20% between those days (impossible to say exactly how much due to rounding error).

3) The results aren't controlled or blinded, in particular vaccinated people may have changed their behaviour, and given the information available about the lags before protection is achieved,  may have made greater changes in the latter part of the period.

 

So efficacy might well be closer to 90%, particularly for a younger population &/ over a longer period.

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7 minutes ago, onebir said:

60% is quite a bit lower than >90% though. I think that latter figure could still be valid though:

1) IIRC the stage 3 trials used people under 60 (so in effect, Israel has conducted a trial on almost ALL of a previously more or less untested subgroup. Good idea? I think not...)

2) The 'plateau' is only apparent between days 23 & 24, and is only apparent in infections - hospitalisations dropped further, maybe as much as 20% between those days (impossible to say exactly how much due to rounding error).

3) The results aren't controlled or blinded, in particular vaccinated people may have changed their behaviour, and given the information available about the lags before protection is achieved,  may have made greater changes in the latter part of the period.

 

So efficacy might well be closer to 90%, particularly for a younger population &/ over a longer period.

1.  It was tested on older folks. Pfizer used a wide age range in phase 3, reporting group efficacy for  those > 65y and those > 75y.

 

2. Yes, I doubt the plateau is real because the numbers are averaged. The curve surely continues down.

 

Phase 3 was the controlled study. From here on, it will be real world numbers and these are particularly encouraging. Especially since this group was all over 65.

 

https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-announce-publication-results-landmark

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29 minutes ago, rabas said:

Pfizer used a wide age range in phase 3, reporting group efficacy for  those > 65y and those > 75y.

Ok but did they report a difference in efficacy between those groups?

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18 minutes ago, onebir said:

Ok but did they report a difference in efficacy between those groups?

Very little. They reported

-- 94% for  the group > 65 years, which includes those >75

-- they reported  efficacy was  relatively uniform across all age groups.

-- And this quote: from here

 

"The Pfizer study presented estimates of the effectiveness in older people and found efficacy >90% in >55, > 65 and >75 year olds, though confidence intervals were wider in the older age groups.

 

That suggests ~90% on  >75y olds. 

 

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