PHE

Devastating New Data From PHE Shows Vaccine Effectiveness Down to 17% and No Reduction in Infectiousness – But Mortality Cut by 77%

Public Health England yesterday released their latest technical briefing on the variants of concern, number 20, and it has some illuminating data.

It provides us with the infection, hospitalisation and death rates for the Delta variant, broken down by vaccination status and age. This allows us to do a calculation of the real-world vaccine effectiveness in the over-50s during the Delta surge, albeit a rough one without any adjustments.

The latest report has data up to August 2nd. If we substract from these values the data in Briefing 17 (up to June 21st) then we get the data covering the period June 22nd to August 2nd, which broadly corresponds to the bulk of the Delta surge in the U.K. The vaccine rollout to the over-50s was basically complete by this point, having stabilised according to PHE at around 88% double vaccinated and 10% unvaccinated (the other two per cent remaining single vaccinated, perhaps due to a bad reaction to the first dose).

In this period the PHE data tells us there were 2,464 Delta cases in the unvaccinated over-50s and 17,926 in the fully vaccinated over-50s. From this we can estimate the vaccine effectiveness against infection in the over-50s during the Delta surge as 17% (1-[(17,926/88%)/(2,464/10%)]). This confirms using additional data the estimate I made last week.

We can make a similarly rough calculation of the vaccine effectiveness against death. Between June 22nd and August 2nd, PHE reports that among the over-50s there were 339 deaths with the Delta variant in the double vaccinated and 167 in the unvaccinated. Using the same proportions vaccinated and unvaccinated as above, this gives a vaccine effectiveness against death in the over-50s during the Delta surge of 77% (1-[(339/88%)/(167/10%)]). Interestingly, this is very similar to the latest estimate of vaccine effectiveness against serious disease from Israel, which is around 80%. This is a decent level of protection and helps explain why the Delta surge had proportionally fewer hospitalisations and deaths, but it is well below the levels suggested by earlier studies and quoted by PHE, which are north of 95%.

Positive Covid Tests Drop Week-on-Week for 10th Day in a Row

Positive Covid tests fell again today, both compared to yesterday and compared to last Saturday, making it the tenth day in a row reported infections have dropped week-on-week. MailOnline has more.

Covid cases have fallen week-on-week for the tenth day in a row, in another sign of hope as the pandemic appears to be shrinking — but experts warn the drop off could be down to less [sic] people getting tests.  

Department of Health bosses posted 26,144 infections today, down 17.8% on last Saturday’s figure of 31,795.

And the number of people dying with the virus has fallen to 71. The number of victims decreased 17.4% from 86 last Saturday.

The baffled Government scientists, whose gloomy predictions continue not to materialise, have now come up with another reason why positive test reports might be dropping: people are avoiding being tested because they don’t want to self-isolate.

I suppose some will be, with holidays approaching. But the ONS breakdown by age also suggests there’s a difference in the infection rate between people under 16 and over 16, with the latter having peaked while the former had not as of July 24th. That in itself is a bit confusing, as children under 16 don’t live on their own, but it does suggest that some of the drop in positive tests reported by PHE might be because parents have stopped testing their children.

PHE Data Shows Vaccine Effectiveness Reduced to Just 17% In Over-50s

The data from the two most recent technical briefings (No. 18, published July 9th, and No. 19, published July 23rd) from Public Health England shows that vaccine effectiveness against infection in the over-50s has plummeted to just 17% in the month between June 21st and July 19th, which corresponds to the main Delta surge.

The data is derived by subtracting the figures in table 5 in briefing 18 (up to June 21st) from those in briefing 19 (up to July 19th) to give just the data for the intervening period.

Briefing 18 gives 9,885 ‘cases’ of the Delta variant in those over 50 who have received at least one vaccine dose and 1,267 ‘cases’ in the unvaccinated over 50 up to June 21st. Briefing 19 gives 18,873 ‘cases’ in the vaccinated and 2,337 in the unvaccinated for the period up to July 19th. Subtracting the earlier from the later gives 8,988 ‘cases’ in the vaccinated and 1,070 in the unvaccinated for the month from June 21st to July 19th.

To calculate the vaccine effectiveness we need to know the infection rate in the vaccinated and unvaccinated groups. According to the PHE week 29 surveillance report, as of July 18th, 20,331,977 people over 50 in England were vaccinated and 2,016,818 were unvaccinated. This gives an infection rate in the vaccinated of 0.044% and an infection rate in the unvaccinated of 0.053%.

Vaccine effectiveness can be calculated by dividing the infection rate in the vaccinated by the infection rate in the unvaccinated and taking away from 100%. Thus 0.044/0.053 gives a vaccine effectiveness of 16.7%, which rounds to 17%.

PHE has recently published a study in the NEJM claiming vaccine effectiveness against the Delta variant of 67% for AstraZeneca and 88% for Pfizer. However, that was using data from April and May when prevalence was very low. This data is from the recent surge in the Delta variant, which is when vaccine effectiveness is really tested. Like recent data from the surge in Israel, it shows that vaccine effectiveness against infection is not holding up.

As noted yesterday, vaccine effectiveness against serious disease and death appears to be holding up much better. This means that those who see vaccines as the necessary pre-condition to removing restrictions don’t need to change course. However, it does indicate that vaccines do little to prevent infection or transmission and so there is no justification for vaccinating young people and children to protect others, or for any coercive measures like vaccine passports. Each person can be free to weigh up the risks and benefits of being vaccinated for themselves.

This article has been updated.

New Data Casts Doubt on the Effectiveness of Covid Vaccines Against Infection

A snapshot of data from the beginning of the month in Israel suggests that the Pfizer vaccine is not protecting against infection now the Delta variant is in town, with infections in the vaccinated across all age groups being no less than you’d expect if the vaccine did nothing.

Could there be another explanation here? Possibly. It’s only a snapshot. What if infections in the unvaccinated peaked earlier than in the vaccinated, as ZOE data at one point showed happening in the U.K.?

Talking of ZOE data, in the middle of last week the study updated its methods (described here) which had the result of completely removing the peak in the unvaccinated infections and replacing it with the opposite, a further climb (see below, the old method put the peak around July 1st).

NHS Says 66% of 18-30s Are Vaccinated as of July 18th – But PHE Says its 59%. Don’t They Know?

The NHS has announced that around two thirds of people aged 18-29 in England have now had one vaccine dose. The Telegraph reports.

A third of young adults in England have still not had a first dose of a COVID-19 vaccine, new figures show.

Around 66.4% of people aged between 18 to 29 had received a first dose as of July 18th, according to estimates from NHS England.

This means 33.6% are likely to be unvaccinated – the equivalent of around 2.9 million adults under 30.

The data shows that vaccine uptake continues to be lower among men than women, with only 65% of men aged 25 to 29 having had a first dose, compared with 71.9% of women in the same age group.

Yet the update from Public Health England, out today, with data up to July 18th, reports the same figure as 59%. It also shows the trend flattening, suggesting it’s unlikely to hit 66% very soon.

What’s going on? This is a difference of around 600,000 people. Don’t they know how many they have vaccinated? How can they disagree by over half a million people?

Stop Press: A reader has got in touch with an explanation.

The PHE figure would appear to be sound see here.

Scroll to the bottom. You’ll see that the 18-24 age group is 59.07% and for 25-29 age group it’s 59%.

The problem is that when the NHS report 66.4% vaccinated this is a deception. For the general population statistic, they arrive at this number by taking total vaccinations and dividing by the population in mid 2019. Of course, many who have had vaccinations have (either due to, or for other reasons) sadly died. (I notice that they’ve just updated this to the mid 2020 population, but it’s still not accurate.)

Meanwhile, the PHE statistic is based on vaccinations given to those in an age group with an NHS number. It’s a reasonable guess that those without an NHS number are less likely to go for an NHS vaccine.

Last time I wrote, I predicted that the error was at least 1.5% and growing.

The statistic you quote suggests the error to be more than 6%.

Applied to the country as a whole, this would mean that only 81.7% of the population has been vaccinated.

The statistic the NHS use is simply not a percentage. It is a deceptive misuse of statistics which is mathematically wrong.

The statistic is so badly wrong, that it is possible that in the future it will be possible to have more than 100% of the population vaccinated.

I believe for this reason that once they start vaccinating children they may switch the statistic.

At the moment, if you are to use the total vaccinations given then you must divide this by the total population in 2021.

Total vaccinations = 46,433,845
Total UK population = 68,265,710

So the total with one dose vaccinated is: 46,433,845/68,265,710 = 68%

This is not as impressive a figure, but it sits in the 60%-80% target we were all told about for herd immunity, and given the additional natural immunity, it’s fair to say that the whole lockdown/rules and nonsense can now come to an end.

We all know, though, that they won’t.

Reports of Reinfection With the Delta Variant are Greatly Exaggerated

There are reports today that the Delta variant is much more likely to reinfect people than the Alpha variant. The Telegraph has the story.

People who have previously caught Covid are now more likely to be reinfected because of the delta variant, a study has found.

Laboratory analysis revealed that the mutation that originated in India is four times more able to overcome protective antibodies from a previous infection compared to the U.K.’s alpha variant.

The study also found that a single dose of either the Pfizer or AstraZeneca vaccines provided just 10% protection against the delta variant.

The variant was already thought to be up to 60% more infectious than the version which swept the U.K. last winter.

The findings, published in the journal Nature, help explain why the virus is spreading so quickly, particularly among younger adults, fewer of whom are double-vaccinated.

It’s important to be aware that this is just a set of laboratory tests on one virus sample. It involves no examination of real world reinfection rates.

Furthermore, it only tests antibodies, not T cells, so is not giving a full picture of the immune system’s response. As the authors admit, one limitation of the study is “the lack of characterisation of cellular immunity, which may be more cross-reactive than the humoral response”.

The claim that a single dose of the vaccines only gives 10% protection against infection with the Delta variant is also not based on any measurement of real world infection rates but on how many of the antibody blood samples “neutralised” the virus in the virus sample. While it may be true that one dose of the vaccines gives limited protection against the Delta variant, this is not the way to quantify it.

The study argues its findings suggest the need to vaccinate those previously infected to boost their immunity: “These results strongly suggest that vaccination of previously infected individuals will be most likely protective against a large array of circulating viral strains, including variant Delta.”

However, without studies on cellular immunity and real world reinfection rates such a conclusion would be very premature.

Real world data suggests the threat is overblown. Public Health England today reports on the latest reinfection data from the SIREN study of healthcare workers, stating that “reinfections remain at very low numbers in individuals previously either PCR positive or seropositive”. There have been just 16 potential reinfections between April and June 27th in the 44,546 people in the cohort, of which over 9,800 have confirmed previous infections. While 95% of the group are fully vaccinated, only one of the 16 possible reinfections was in the 5% who are unvaccinated. This strongly suggests the real world risk of reinfection, whether vaccinated or unvaccinated, is very small.

Indian Variant Infectiousness Falls Again, PHE Data Shows – Just 10.7% of Contacts Become Infected. So Why Isn’t COVID-19 More Infectious?

The latest Public Health England (PHE) Technical Briefing on the variants of concern is out, and it shows that the infectiousness of the Delta (Indian) variant has dropped again, so that it is now at the same level as the Alpha (British) variant was at the end of March.

Data from PHE

The Delta variant secondary attack rate (SAR – the proportion of contacts an infected person infects) is down to 10.7% this week, from 11.4% a week ago (see graph above). That means that around 90% of the close contacts of people infected with the Delta variant are not infected by them. Once again, this shows how claims that the Delta variant is “60% more transmissible” or similar fail to make clear that transmissibility changes and often declines over time, and that even if the Delta variant is currently more infectious than the Alpha variant it is still less infectious than the Alpha variant was when it first appeared on the scene.

You might be wondering, though, how a disease that only infects 10-15% of close contacts, even at the height of an epidemic wave, can be called highly infectious. And indeed, how such a disease can cause an explosive epidemic wave at all, and why those waves crash down as quickly as they arise despite not exhausting the pool of susceptible people.

If you do wonder that, you would not be alone. A famed epidemiologist called Robert Edgar Hope-Simpson spent his life observing the idiosyncrasies of seasonal influenza and summarised some of his thinking in a 1981 article entitled “The role of season in the epidemiology of influenza“. More recently, in 2008, a group of scientists took up Hope-Simpson’s investigations (which were inconclusive) and summarised seven conundrums of influenza that he identified, all of which apply equally to COVID-19:

PHE’s Latest Vaccine Study Suggests Hospitalisation Risk INCREASES After the Second Dose

It’s not two weeks since Lockdown Sceptics was casting doubt on Public Health England’s alarming claim that the Delta (Indian) variant had more than double the risk of hospitalisation of the Alpha (British) variant. How long will they take to backtrack after the panic has done its damage, we asked?

Well, it turns out that even before Boris took to the podium on Monday PHE had already released a new study claiming that vaccines after all are more effective at preventing hospitalisation against the Delta variant than the Alpha variant. Here’s the story in the Telegraph:

Vaccines are more effective at preventing hospitalisation against the Indian/delta variant than they were against previous types, once people are double-jabbed, new data shows.

Real world data shows the Pfizer/BioNTech vaccine is 94% effective against hospital admission from the variant after one dose, rising to 96% after two jabs.

The Oxford/AstraZeneca vaccine was found to be 71% effective against hospital admission after one dose, rising to 92% after two jabs.

In both cases, two doses had a greater impact preventing hospitalisations than was the case with the Kent variant. 

The new study and the earlier study aren’t quite showing the same thing. The earlier study showed the risk of hospitalisation with the Delta versus Alpha variant for all those testing positive, not just the vaccinated, though subsequently adjusted the results for “vaccination status”. The new study specifically looks at the hospitalisation risk in those vaccinated with respect to the Alpha and Delta variants and compares them. However, the two studies should come to broadly the same conclusion, as they are both looking at how much more serious disease is with the Delta variant. At any rate, given that a large proportion of the vulnerable population is now fully vaccinated, we certainly shouldn’t see a doubling in the hospitalisation rate with the Delta variant if, as is claimed in the new study, the vaccines are better at preventing serious disease from that variant.

Ross Clark suggests the problem with the earlier data was that the sample size was small and biased. As he notes, PHE’s modelling misses the most obvious data point, that the rate of hospitalisations per case has not increased as the Indian variant has become dominant (see graph below). How then can the Indian variant have twice the risk of hospitalisation?

Is the new study any more reliable than the earlier one? As usual with a PHE observational study, it’s hard to tell, as much of the method is hidden behind opaque statistical techniques with working that is not set out. All the reader knows is that raw data is taken and transformed by some statistical process into hazard ratios and vaccine effectiveness estimates that are all but impossibly to verify. What we can do, though, is look at the results of this largely concealed data-processing and see if it makes sense.

Below is the table from the study (there’s only one, it’s a very short paper), and it shows something very curious.

Claims the Indian Variant is “Hyper-Transmissible” are Nonsense – And Here’s the Graph that Proves It

Yesterday I wrote about the latest Public Health England (PHE) report claiming that the Delta (Indian) variant is much more infectious than the Alpha (British) variant. I noted that the main measure of transmissibility – the secondary attack rate (i.e., the proportion of contacts that an infected person infects) – has varied over time.

It occurred to me that it would be useful to plot these attack rate values to show them graphically. So I went through the 15 technical briefings released by PHE so far and extracted the secondary attack data for the three variants (Wuhan, Alpha, Delta) and plotted them in the graph above.

There are a few points worth making from this about the infectiousness of the Covid variants.

First, between 85% and 92% of the contacts of all those infected with any of the COVID-19 variants do not get infected. This is an indication of the high level of immunity (i.e., low level of susceptibility) in the population and the low absolute infectiousness of the virus.

Second, new variants appear to start off with – or quickly acquire – a high attack rate compared to established variants, a rate which then declines. The decline for the Alpha variant occurred prior to any significant vaccine coverage meaning it cannot all be attributed to the vaccines. Conversely, despite the high vaccine coverage in April and May the Delta attack rate spiked. Nonetheless, it has already sharply declined. (The reason for the sudden drop in the Alpha attack rate from 10% to 8% at the end of April is unclear.)

Third, the Alpha variant was once more transmissible than the Delta variant at its recent peak, but is now much less transmissible.

While more data from more variants would help to confirm the patterns here, the data so far suggest that new variants will often be more infectious than established variants to begin with, but this will not last. Further, the degree of infectiousness appears to arise more from factors such as the epidemic phase or the season than inherent properties of the variant, save insofar as the new variant is slightly better at evading our immune defences for a time. And I mean slightly. Only 3% more contacts of those infected with the Delta variant are being infected compared to the Alpha variant, a difference that is dropping week on week.

The upshot is we should stop being frightened by claims that the latest new variant is “50% more infectious”, which are a distraction, and focus on levels of serious disease and how best to cope with them.

PHE Briefing Claims Indian Variant is 64% More Infectious – But Dig Down and the Finding Falls Apart

Public Health England (PHE) released its latest technical briefing (number 15) yesterday on “variants of concern” which claimed the Delta (Indian) variant is 64% more infectious than the Alpha (British) variant. But look closer and you find this headline finding is not all it seems.

In the underlying study the researchers admit they did not control for the crucial factor of household size – bigger households will tend to have more secondary infections because there are more people in the household being exposed. The authors acknowledge that many of the Delta variant households may have been larger than Alpha variant households (say, because of different proportions of different ethnic groups), and also that many of the matched controls may have lived alone – they have no way of knowing.

We did not have information on household size, which is likely to have an effect on the estimates of transmissibility. For example, some controls (sporadic cases) will have lived alone and have no chance of onward transmission within their residence and therefore becoming a household cluster. However, we were unable to identify and exclude these cases in the analysis. Further studies of household transmission that includes denominators of all individuals in the household and their vaccination status are needed to provide improved estimates of household transmission and allow for the calculation of household secondary attack rates.

This factor by itself undermines the entire 64% claim and means it should be ignored.

Separate to this, the technical briefing provides some raw data on secondary attack rates (the proportion of contacts infected people infect) that give us an important insight into the real transmissibility of the variants.