Vaccine efficacy

New PHE Data Shows Vaccine Effectiveness Against Delta Down to Just 7.6% in the Over-50s, 24% in the Under-50s, as the Vaccinated Continue to Experience Higher Infection Rate

The latest Technical Briefing on the Variants of Concern, number 23, has been published by Public Health England (PHE), so we can update our (unadjusted) estimates of vaccine effectiveness against the Delta variant using the data it includes from sequenced Delta samples from positive PCR test results in England.

As before, we subtract the figures in the latest briefing, now no. 23, from those in briefing 17 to give the figures for the period June 22nd to September 12th. This gives us a picture for the whole Delta surge, which allows for the fact that most of the early reported infections were in the unvaccinated and most of the later reported infections were in the vaccinated (see below). PHE has recently also published the most recent month’s data for all reported infections (not just sequenced Delta ones), which shows lower vaccine efficacy in the most recent four weeks (a new report released on Friday shows this has dropped even further in the most recent week). However, given the apparently delayed infections in the vaccinated, it seems most accurate to look at the figures for the whole surge, not just the last month, when estimating vaccine efficacy against Delta.

We also use figures for proportions of the population vaccinated by age derived from the PHE Covid surveillance reports.

Starting with the over-50s, for the period June 22nd to September 12th, PHE reports 68,445 Delta infections in the double vaccinated and 7,575 in the unvaccinated. PHE figures show that in this period the proportion of the over-50s double vaccinated increased from 87% to 89%, giving a mean of 88%, and the proportion unvaccinated was stable at 9%. Calculating the vaccine effectiveness against Delta infection in the over-50s (1-(68,445/88%)/(7,575/9%)) gives a figure of just 7.6%. This is down from 15% two weeks ago and 24% two weeks before that. This continues to be very different to the estimate in the recent Oxford University study using ONS survey data, a study which I criticised for numerous inconsistent and implausible findings.

With regard to deaths with Covid (within 28 days of a positive test), PHE reports 1,515 in the double vaccinated and 552 in the unvaccinated in the over-50s in this period. This works out (1-(1,515/88%)/(552/9%)) at a vaccine effectiveness against death of 72%, down slightly from 74% using data from the previous briefing. This is a 72% reduction in mortality including any reduced risk of infection, not in addition to it. It continues to be an encouraging figure, albeit lower than earlier studies have suggested, and dropping week on week.

For the under-50s, for the period June 22nd to September 12th, PHE reports 81,718 Delta infections in the double vaccinated and 195,957 in the unvaccinated. PHE figures show that in this period the proportion of under-50s double vaccinated increased from 18% to 42%, giving a mean of 30%, and the proportion unvaccinated decreased from 61% to 50%, giving a mean of 55%. Calculating the vaccine effectiveness against Delta infection in the under-50s (1-(81,718/30%)/(195,957/55%)) gives a figure of 24%. This is down from 27% two weeks ago and 37% two weeks before that, and though higher than in the over-50s, is still very low and much lower than earlier studies (including the trial) indicated.

For deaths, PHE reports 48 in the double vaccinated and 126 in the unvaccinated in the under-50s in this period. This works out (1-(48/30%)/(126/55%)) at a vaccine effectiveness against death of 30%. This is up from 20% two weeks ago and 12% two weeks before that, but is still very low and much lower than in the over-50s. This may be because higher risk people are prioritised for vaccination, or are more likely to consent to it, in the younger age groups, and the rising efficacy may reflect the increase in lower risk people being vaccinated.

These figures are much lower than those commonly quoted and used in modelling, and if they are closer to the truth then they mean the official, self-congratulatory estimates of “100,000 deaths” and “24.4 million infections” prevented by the vaccines are huge overestimates.

By plotting the differences between the reported total Delta cases in the last five briefings we can also get a picture of how they are changing over time in the different age and vaccine-status cohorts. The red and yellow lines in the chart below show that new reported Delta infections in the unvaccinated have continued gently to increase, as have reported infections in the vaccinated over-50s (dark green line). On the other hand, new reported Delta infections in the vaccinated under-50s dropped in the last two weeks, driving an overall drop in reported Delta infections in the vaccinated. This may mark the peak of the Delta surge in the vaccinated, and possibly overall, though the gentle rise in reported infections in the unvaccinated since the start of August adds a smidgen of doubt into that inference.

Why is the ONS Claiming Just 1% of Covid Deaths Are in the Vaccinated When PHE Data Shows the True Figure For August was 70%?

The ONS has published a new study on Covid deaths which purports to show how few vaccinated people die of Covid. Here’s how the Telegraph reported the headline claim: “Only 59 fully vaccinated people without serious health conditions died from COVID-19 out of more than 50,000 deaths in England this year, new figures from the Office for National Statistics (ONS) show.”

The Telegraph report continues:

In the first study of deaths by vaccination status, the ONS found that around 99% of COVID-19 deaths between January 2nd and July 2nd 2021 were in people who had not had two doses.

Overall 640 (1.2%) of deaths were in those who had received both vaccine doses, but the ONS said many of those could have been infections picked up before the second dose. 

Just 256 deaths (0.5%) were considered true “breakthrough” infections where the second dose had long enough to work, but still did not offer protection. 

However, the average age of those “breakthrough” infections was 84 and the majority (76%) were classed as “extremely clinically vulnerable”. Just 59 did not have serious medical conditions.

These statistics appear remarkable – until you realise what they’ve done. Although the data is presented as “this year” in fact the cut-off date is July 2nd. That is significant because it is just before the Delta surge got going. This means the data all comes from the Alpha surge, when almost no-one was vaccinated and tens of thousands of Covid deaths were reported, and from the quiet spring and early summer when many were vaccinated but almost no-one died (see chart below).

Robert Peston Shocked by Lack of Debate on Vaccine Effectiveness – Before Caving to Critics and Apologising for Questioning Vaccine Effectiveness

I wrote earlier in the week about the latest vaccine data from Public Health England (PHE) and how it shows that in the last month reported infection rates have been higher in the double vaccinated than in the unvaccinated for those aged 40-79 – up to 38% higher in some age bands.

Usually, data like this that casts the vaccines in a bad light is not reported by major media outlets – they tend to stick only to reporting on the press releases from actual studies rather than presenting implications from real-world data, which means they typically include whatever spin and ‘adjustments’ the researchers have added.

Unusually, this time Robert Peston decided to report on the new PHE data for ITV News. Inspired it seems by the fact that he has just had Covid despite being double-vaccinated, he wondered how many others had experienced similar, and was surprised to find in the data that it was actually very common.

He remarks: “I am surprised these statistics have received so little attention and have occasioned so little debate.”

Why is he surprised, though, when the fact is PHE has been publishing statistics like these for months showing that the infection rate in the vaccinated has been rising. Most journalists haven’t reported on them before, including Peston (who seems unaware of them, given that he is discovering this data for the first time), so why would they start now? Particularly when the vaccine surveillance report they come from specifically warns readers against using the raw data to estimate vaccine effectiveness and refers them to the published studies summarised higher up. Nothing to see here, is the message.

If Peston was unsure why other journalists weren’t reporting on this data, he soon found out, as the Twitterati piled on him for daring to cast the vaccines in a negative light. Many accused him of failing to recognise that this was just because the large majority of people over 40 were vaccinated, so of course they had more infections – which only made themselves look foolish as Peston was clearly quoting rates by vaccination status (the proportions of the vaccinated and unvaccinated who were infected), so this was accounted for. The statistics show the double vaccinated have higher rates of infection than the unvaccinated – that was his point.

Vaccines Have NEGATIVE Effectiveness in the Over-40s, as Low as MINUS 38%, Shows New PHE Report

Public Health England (PHE) published their latest weekly vaccine surveillance report on Thursday. Usually these just summarise other studies so are not particularly interesting, but this week something new appeared that has been widely asked for but elusive: data on cases, hospitalisations and deaths broken down by age and vaccination status.

Although the fortnightly technical briefings on the variants of concern have a breakdown of sequenced Delta cases broken down by vaccination status and into the over-50s and under-50s, this is the first time PHE has published general data on all cases (not just sequenced ones) split up by age and vaccination status.

The data comes from the Second Generation Surveillance System (SGSS), the relationship of which to the Government dashboard data is unclear, though the figures are similar. It reports 722,728 cases in the reporting period, compared to the dashboard figure of 727,010 by specimen date, so this seems comprehensive. On the other hand, it includes 6,605 hospitalisations, whereas the dashboard has 21,242, more than three times as many, though this may be due to how it counts hospitalisations (“Cases whom [sic] presented to emergency care (within 28 days of a positive specimen), resulting in overnight inpatient admission”). It has 2,381 deaths, against the dashboard’s 2,496, so again this is most of them.

It is just data for the past month, August 9th to September 5th. We can use it to calculate a rough estimate of unadjusted vaccine effectiveness in different age cohorts for this four-week period.

PHE Data Update: Vaccine Effectiveness Just 15% in Over-50s, 27% in Under-50s. Deaths Cut by 74% in Over-50s, But Just 20% in Under-50s

The latest Technical Briefing on the variants of concern, number 22, has been published by Public Health England (PHE), so we can update our (unadjusted) estimates of vaccine effectiveness against the Delta variant using the data it includes from sequenced Delta samples from positive PCR test results in England.

As before, we subtract the figures in briefing 22 from those in briefing 17 to give the figures for the period June 22nd to August 29th. We also use figures for proportions of the population vaccinated by age derived from the PHE Covid surveillance reports.

Starting with the over-50s, for the period June 22nd to August 29th, PHE reports 47,874 Delta infections in the double vaccinated and 5,748 in the unvaccinated. PHE figures show that in this period the proportion of the over-50s double vaccinated increased from 87% to 89%, giving a mean of 88%, and the proportion unvaccinated was stable at 9% (Note: not 10% as I stated previously). Calculating the vaccine effectiveness against Delta infection in the over-50s (1-(47,874/88%)/(5,748/9%)) gives a figure of 15%. This is the same as the figure I calculated two weeks ago, though now using the more accurate figure of 9% rather than 10% for the proportion unvaccinated. This means that it represents a decline (using 9% for the previous calculation would give a VE of 24%). This continues to be very different to the estimate in the recent Oxford University study using ONS survey data, a study which I criticised for numerous inconsistent and implausible findings.

With regard to deaths with Covid (within 28 days of a positive test), PHE reports 1,004 in the double vaccinated and 399 in the unvaccinated in the over-50s in this period. This works out (1-(1,004/88%)/(399/9%)) at a vaccine effectiveness against death of 74%, down slightly from 75% using data from the previous briefing (even with the change to 9% unvaccinated). This is a 74% reduction in mortality including any reduced risk of infection, not in addition to it. It continues to be an encouraging figure, albeit lower than earlier studies have suggested, and dropping week on week.

For the under-50s, for the period June 22nd to August 29th, PHE reports 58,714 Delta infections in the double vaccinated and 160,143 in the unvaccinated. PHE figures show that in this period the proportion of under-50s double vaccinated increased from 18% to 39%, giving a mean of 28%, and the proportion unvaccinated decreased from 61% to 51%, giving a mean of 56%. Calculating the vaccine effectiveness against Delta infection in the under-50s (1-(58,714/28%)/(160,143/56%)) gives a figure of 27%. This is down from 37% two weeks ago, and though higher than in the over-50s, is still very low and much lower than earlier studies (including the trial) indicated.

For deaths, PHE reports 37 in the double vaccinated and 93 in the unvaccinated in the under-50s in this period. This works out (1-(37/28%)/(93/56%)) at a vaccine effectiveness against death of 20%. This is up from 12% two weeks ago, but is still very low and much lower than in the over-50s. This may be because higher risk people are prioritised for vaccination, or are more likely to consent to it, in the younger age groups.

These figures are much lower than those commonly quoted and used in modelling, and if they are closer to the truth then they mean the official, self-congratulatory estimates of “100,000 deaths” and “24.4 million infections” prevented by the vaccines are huge overestimates.

By plotting the differences between the reported total Delta cases in the last four briefings we can also get a picture of how they are changing over time in the different age and vaccine-status cohorts. The red and yellow lines in the chart below show that new Delta infections in the unvaccinated have started to increase again, but not by as much as those in the vaccinated (for this purpose, all who are at least 21 days after their first dose), which have continued to surge. A majority of new infections (57,565 out of 94,148, or 61%) are now in the vaccinated. This means that the recent increase in reported infections in England is being driven primarily by infections in the vaccinated. The fainter lines show the trends in the over- and under-50s, indicating that in both age cohorts new Delta infections in the vaccinated now outnumber those in the unvaccinated, and that new infections in the vaccinated over-50s are increasing particularly fast. This helps to explain the declining vaccine effectiveness estimates given above.

The Push for Vaccination of Children and Vaccine Boosters Despite the Lack of Evidence They Prevent Infection or Transmission is Approaching a Religious Mania

As the Government’s Joint Committee on Vaccination and Immunisation (JCVI) gives the go-ahead for third-jab boosters for the most vulnerable, political pressure is mounting on it also to approve a wider rollout of boosters as well as inoculations for 12-15 year-olds.

Asked if the JCVI should get a “wiggle on” about decisions on boosters and jabs for children, Education Secretary Gavin Williamson told Sky News: “Speaking as a parent myself, I think parents would find it incredibly reassuring to know that they had a choice as to whether their child would be vaccinated or not.”

Former Health Secretary and current Chairman of the Commons Health Select Committee Jeremy Hunt tweeted: “The latest study from King’s College London showed vaccine effectiveness dropping after six months, so why are we hanging around?”

Is it really appropriate for ministers and MPs to be putting pressure on a Government advisory body to give the answers they want to hear? How is that following ‘the Science’?

For its part, the JCVI has indicated that it wants to wait for more evidence, and also appears to have a split of opinion among its members. However, the Government may have successfully forced the issue, with the Guardian reporting that the committee held a long discussion on children’s vaccination on Thursday, followed by a vote, and that a decision may be announced as soon as Friday.

Previously, JCVI Chairman, Professor Anthony Harnden, had said he thought it “highly likely” there will be a booster programme, with decisions “over the next few weeks”. He told BBC Radio 4’s Today programme that there are questions about which variant to target with the boosters, and identifying who really needs one.

What we don’t want to do is boost people and then find we have a new variant and we can’t boost them again because we’ve boosted them too soon – and those people might not have needed the booster in the first place. So there’s a lot of very complicated modelling and data analysis that is going on about this at the moment.

JCVI member Professor Adam Finn is clear that the “main objective” of vaccination should be to protect against serious illness, and that the evidence of waning immunity against infection is something to monitor not an urgent call to action.

I think the ZOE study, and a couple of other studies we recently had, do show the beginnings of a drop off of protection against asymptomatic or mildly symptomatic disease. But other studies are showing maintenance of good protection against serious illness and hospitalisation.

In May he told the Today programme that children should not be immunised if at all possible as a matter of principle.

In normal times, just as in pandemic times, we simply wouldn’t want to immunise anybody without needing to. It’s an invasive thing to do, it costs money, and it causes a certain amount of discomfort, and vaccines have side effects. So if we can control this virus without immunising children we shouldn’t immunise children as a matter of principle.

Are the Vaccines Declining in Effectiveness Against Serious Disease?

Reported positive ‘cases’ have been increasing slightly in the U.K. recently, though the trend appears to be flattening.

United Kingdom

Interestingly, the rise has been concentrated outside England, which has been declining in the last week or so.

England

Scotland has seen the most striking rise, linked it appears to the return of children to school on August 18th.

Scotland

The Scottish surge in ‘cases’ is linked to a surge in testing – it seems that parents have not been testing their children over the summer, and the requirement to do so for school has picked up a load of hidden infections (presumably these children and their families have not been isolating over the summer either).

Latest PHE Data Shows Vaccine Effectiveness Down to Just 15% in the Over-50s, 37% in the Under-50s. Deaths Cut by 76% in Over-50s, But Just 12% in Under-50s

Public Health England (PHE) has released a new technical briefing on the variants of concern, number 21, and this allows us to update our estimate of (unadjusted) vaccine effectiveness against the Delta variant using the data it provides on confirmed Delta cases.

We subtract the figures in briefing 21 from those in briefing 17 to give the figures for the period June 22nd to August 15th. We also use figures for proportions of the population vaccinated by age derived from the PHE Covid surveillance reports.

Starting with the over-50s, for the period June 22nd to August 15th, PHE reports 29,282 Delta infections in the double vaccinated and 3,915 in the unvaccinated. PHE figures show that in this period the proportion of the over-50s double vaccinated was stable at 88% and the proportion unvaccinated was 10%. Calculating the vaccine effectiveness against Delta infection in the over-50s (1-(29,282/88%)/(3,915/10%)) gives a figure of just 15%, down from 17% using data from the briefing two weeks ago. This is very different to the estimate in the recent Oxford University study using ONS survey data, a study which I criticised for numerous implausible findings.

With regard to deaths with Covid (within 28 days of a positive test), PHE reports 602 in the double vaccinated and 280 in the unvaccinated in the over-50s in this period. This works out (1-(602/88%)/(280/10%)) at a vaccine effectiveness against death of 76%, down slightly from 77% using data from the previous briefing. This is a 76% reduction in mortality including any reduced risk of infection, not in addition to it. It’s an encouraging figure, albeit lower than earlier studies have suggested.

For the under-50s, for the period June 22nd to August 15th, PHE reports 36,855 Delta infections in the double vaccinated and 125,394 in the unvaccinated. PHE figures show that on June 20th 61% of under-50s were unvaccinated while 18% were double vaccinated. On August 15th those figures were 52% unvaccinated and 35% double vaccinated. Taking the average of these gives 56% unvaccinated and 26% double vaccinated for the period. Using this to calculate the vaccine effectiveness against Delta infection in the under-50s (1-(36,855/26%)/(125,394/56%)) gives a figure of 37%. This is higher than in the over-50s, but still very low and much lower than earlier studies (including the trial) indicated.

For deaths, PHE reports 27 in the double vaccinated and 66 in the unvaccinated in the under-50s in this period. This works out (1-(27/26%)/(66/56%)) at a vaccine effectiveness against death of just 12%. Why this would be so much lower than in the over-50s is unclear, but it’s worth bearing in mind that these are small numbers of deaths which may make the estimate unreliable.

These figures are much lower than those commonly quoted and used in modelling, and if they are closer to the truth then they mean the official, self-congratulatory estimates of “100,000 deaths” and “24.4 million infections” prevented by the vaccines are huge overestimates.

By plotting the differences between the reported total Delta cases in the last three briefings we can also get a picture of how they are changing over time in the different age and vaccine-status cohorts. The red and yellow lines in the chart below show that new Delta infections in the unvaccinated have stayed largely flat over the past fortnight, but those in the vaccinated (for this purpose, all who are at least 21 days after their first dose) have surged, so that a majority of new infections (44,038 out of 76,117, or 58%) are now in the vaccinated. This reveals that the recent modest increase in positive cases in England is being driven primarily by infections in the vaccinated. The fainter lines show the trends in the over- and under-50s, indicating that in both age cohorts new Delta infections in the vaccinated now outnumber those in the unvaccinated. This helps to explain the declining vaccine effectiveness estimates given above.

The Implausible Findings of the Latest Oxford Vaccine Effectiveness Study

Oxford University released a new study on vaccine effectiveness this week based on the ONS Infection Survey. Its headline finding was that, for the period dominated by the Delta variant, the AstraZeneca jab declined from 97% vaccine effectiveness against symptomatic infection to 71% and Pfizer’s declined from 97% to 84%. The researchers note that vaccine effectiveness (VE) appears to wane with time, putting this at 7% per month in the case of AstraZeneca and 22% per month in the case of Pfizer.

One odd thing about these results is that the 97% initial VE for AstraZeneca is very high compared to other estimates, including the vaccine trial which found it to be just 70.4%.

Here are their vaccine effectiveness results in full.

A second oddity is that for the all-infection (positive test) findings, the researchers found Pfizer VE was just 78% in the Alpha period, well below the usual figure – such as that from a major Israeli study, which put it at 92%. But then the researchers found it rose to 80% in the Delta period. A third oddity is that AstraZeneca VE was 71% in the 13 days after the second dose, up from 46% after the first dose even though that’s before the second dose is supposed to kick in. Yet once it is supposed to kick in, after 14 days, VE drops to 67%. These are strange results indeed.

Another perplexing aspect is that the VE estimates against Delta in this study, while (mostly) lower than against Alpha, are much higher than those indicated by recent data from Israel and the U.K., which have included 39% and 17%.

These various oddities piqued my suspicions, so I had a look at the raw data (shown below).

CDC Study Claiming Unvaccinated Have More Than Double the Risk of Re-infection is Full of Holes

The Centers for Disease Control and Prevention (CDC) in America has published a new study claiming to show that, among the previously infected, the unvaccinated are at more than double the risk of re-infection than the vaccinated.

It forms part of their evidence for why people who have had COVID-19 before should get vaccinated and not rely on natural immunity.

It has a number of problems, however.

The study looks retrospectively at data from the U.S. state of Kentucky. The researchers identify all those in the state who were re-infected during May and June 2021 (defined in terms of positive tests a certain number of days apart) and compare their vaccination rates to a control group. They find 246 re-infections in that period, and calculate that those who were not vaccinated were 2.34 times more likely to be re-infected than those who were vaccinated.

The study has a number of limitations, however, some of which the authors acknowledge.

Firstly, the study period of May and June 2021 is notable for being a period of very low prevalence in the state, meaning it is not a good time to study acquired immunity, which is best studied during a new surge when it is most put to the test. The authors themselves acknowledge that because the study covers just one period in one state, the “findings cannot be used to infer causation”.

The authors also acknowledge that test-seeking behaviour may skew the findings to exaggerate vaccine effectiveness, as vaccinated people are probably less likely to get tested.

Another weakness is that the study doesn’t include symptom data so we don’t know whether the “reinfections” were actual disease or just asymptomatic and mild infections of the kind that are characteristic of the immune system working.

A related problem is that there is no discussion of how big the problem of re-infection is from an absolute standpoint. With only 246 re-infections (of unknown severity) in a population of 4.5 million over a two month period, it’s not clear that even if vaccination did halve your probability of re-infection it would be a difference worth getting vaccinated (which carries its own risks) to achieve.