The latest Public Health England Vaccine Surveillance report is very striking.

They report 80% of adult *cases* in past 4 weeks were fully vaccinated, up from 56% in 9 Sept report.

That doesn’t necessarily mean vaccinated are testing positive at a higher *rate* ...

PHE report adult rates are 40% higher amongst vaccinated overall: higher for all ages >29 & more than double for 40-79 year olds.

But PHE use NIMS population estimates which probably overestimate population meaning PHE unvaccinated case rate may be too low ...

The alternative is ONS population which has the opposite problem (i.e. unvaccinated rates using this may be too high). The true rate is probably somewhere in between.

Here are the case rates & implied vaccine effectiveness (VE) using NIMS & ONS population denominators …

We don’t know if the true value is closer to NIMS or to ONS. Using the mid-point would still imply a higher case rate amongst the unvaccinated but only by about 10%, hardly enough to justify vaccine passport, sacking unvaccinated carers etc …

In fact if we look at 18-59s (the group most relevant for sacking carers etc.), the mid-point of the two population estimates would imply nearly identical case rates in vaccinated & unvaccinated.

A few caveats:

1. The rates reported by PHE (and mine using ONS) ignore unlinked cases. Perhaps these are more likely to be unvaccinated, but we don’t know for sure ...
2. Different testing rates may be a factor, but hard to know in which direction
Perhaps some unvaccinated don’t trust Govt & so are less likely to get tested. Others (esp. those not previously infected) will probably will be more likely to get tested to minimise risk ...

3. This does not necessarily mean vaccines don’t reduce infection risk for individuals. The PHE data may be due to a higher % previously infected (so with high levels of immunity) amongst unvaccinated and/or due to other behavioural effects. That said …
... Point 3 is irrelevant to any case for vaccine passports/sacking carers whilst ...

the significant reduction in implied effectiveness over the past 6 weeks is consistent with VE waning.
We’ll have to see if boosters change the trend for older groups over coming weeks …

Finally, implied vaccine effectiveness against death & hospitalisation remains much higher than against *cases*. However, PHE still report 79% of adult deaths and 67% of adult hospitalisations in previous 4 weeks were fully vaccinated.
The PHE report is here:…
... And of course the thread should have referred to UK HSA rather than PHE which it has now replaced.

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More from @cricketwyvern

21 Oct
It’s not libertarian to think that a Govt forcing people to do something like wear masks for everyday activities under threat of criminal sanction should have strong evidence that:
a. there will be significant benefits
b. those benefits are large enough to outweigh costs

the evidence on the effectiveness of mask mandates is weak & conflicting whilst the real world experience of countries/states introducing mandates makes clear that, if there is some marginal benefit, it is not big enough to be observed in the raw data @ianmSC

On the other side, cost of mask mandates is not zero.
Masks are not free, but we can't look only at economic costs. Also:
• environmental costs of disposal
• discomfort (& for a minority, serious distress)
• barriers to communication
• impact on child development
Read 4 tweets
19 Oct
Lots of people that, as our case numbers & deaths are particularly high relative to the rest of Europe, England needs to reimpose restrictions & compulsory masks & start vaccine passports.
It’s a strange take …

Confirmed positive tests are currently relatively high in England but they are by no means the highest in Europe.

Further, high cases are partly explained by mass testing. Testing rates in England currently 9 x Spain, 8 x Germany, 2 x France or Italy.

And crucially …

deaths are actually about half the European average & just below the EU average

(note graph is from Our World in Data graph which shows the UK as a whole. Rates in England currently even lower) …
Read 7 tweets
8 Oct
The latest @UKHSA Vaccine Surveillance report now reports that the vaccinated are testing positive at a higher rate than the unvaccinated for every age group from 30-39 up ...
... The text accompanying this table says "The rate of a positive COVID-19 test is substantially lower in vaccinated individuals compared to unvaccinated individuals up to the age of 39"
I think that is just a typo & should say "up to age of 29" Perhaps @UKHSA can confirm? ...
As noted previously, there is lots of discussion about whether UK HSA are using the most appropriate population denominators & if ONS estimates are used, rates would still be higher amongst unvaccinated for most (though not all) age groups ...
Read 6 tweets
6 Oct
Lots of interesting data in the latest ONS release.
First, reinfection rates continue to be low (though a little higher in the Delta period): they find 296 out of 20,262 (1.4%) people tested positive again, a rate of 12 per 100k person days (about 4 per year). However ...
... only 137 people (0.7%) had a Ct < 30 (i.e. high viral load) when they tested positive a second time.
Further only 88 people (0.4%) reported any symptoms (see Table 1d) ...
... Second, the chance of reinfection increases somewhat over time, but remains very low even after a year.
e.g. Table 2c gives estimated reinfection rates per 100k person-days = 10.8 one year after the 1st infection ...
Read 8 tweets
4 Oct
Vaccine passports are unethical, unlikely to lead to any significant benefits & will cause huge costs. But they have another significant problem:
Under the Govt’s Plan B, the conditions for bringing them in will only happen if (ironically) vaccines are not working well.

The Govt says vaccine passports are being kept in reserve for a situation in which the NHS comes under *unsustainable pressure*.

So what are the circumstances in which that might happen? …

In July England opened up at the peak of a pretty big outbreak: positive tests reached 80% of the highest ever point last winter &, for some age groups & areas, much higher than the winter peak...
Read 11 tweets
30 Sep
Important new peer-reviewed paper on lockdown cost-benefits by Professor Douglas W Allen of @SFU published in the International Journal of the Economics of Business (I am a co-editor) @Routledge_Econ

Currently free to access here:

Using the "mid-point estimates", Prof Allen finds a cost-benefit ratio of about 140 (i.e. costs of lockdown were 140 times greater than benefits).

Even with the most extreme & unrealistic assumption about deaths averted by lockdowns, costs still outweigh benefits …

Note the mid-point estimate assumes lockdowns reduced Covid deaths by 20%.
In fact, Prof Allen concludes we cannot rule out that lockdowns had zero effect on mortality, in which case, the cost-benefit conclusion would be much worse …
Read 7 tweets

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