Thread by @ClimateAudit

UK has published some relatively detailed data showing "unadjusted" rates of case infection of boosted vs unvax by age group.
assets.publishing.service.gov.uk/government/upl… As context, Ontario SciTable only shows "adjusted" case rate purporting to show unvax rate as twice that of vax (2 or more doses)

2/ in ALL UK ages above 30, "unadjusted" case infection rate for triple-vax was HIGHER than among unvax. These results troubled UK authorities who printed unadjusted unvax rates in light gray, warning "comparing case rates ...should not be used to estimate vaccine effectiveness"

3/ the UK conclusion that "comparing case rates among vaccinated and unvaccinated populations should not be used to estimate vaccine effectiveness against infection" will come as news to Ontario SciTable and other authorities which regularly use such data in briefings

4/ UK public health purported to explain this surprising conclusion in a page 38 footnote that said "unadjusted crude rates do not take into account underlying statistical biases in the data and there are likely to be systematic differences between these 2 population groups"

5/ their fourth reason was that unvax were "more likely to have caught COVID-19 in the weeks or months before the period covered in the report. This gives them some natural immunity which may have contributed to a lower case rate in past few weeks".

6/ if, as UK public health say here, natural immunity from prior infection is giving better protection against infection than even triple doses, why isn't that recognized in public policy?

7/ reason three: "many of those who were at head of queue for vaccination are those at higher risk from COVID-19 due to age, occupation, family circumstances or underlying health issues". Uh, data in table was already stratified by age group.

8/ "people who are fully vaccinated and people who are unvaccinated may behave differently, particularly with regard to social interactions and therefore may have differing levels of exposure to COVID-19". If unvax people are behaving more prudently, why do they merit punishment?

9/ "testing behaviour is likely to be different between people with different [vax] status, resulting in differences in chances of being identified as a case".
They seem to hypothesize that vax are more likely to get COVID test for very mild symptoms than unvax, inflating count

10/ "unadjusted" UK case rate data also shows substantial protection for vax in respect to hospitalization and death. That part is in accordance with expectations and messaging.

11/ although UK public health authorities warned that comparison of case rates "should not be used" to estimate vaccine effectiveness against infection, it expressed no such reservations in respect to hospitalization and death rates.

12/ here's a barplot from UK data (Table 9) here assets.publishing.service.gov.uk/government/upl… contrasting unvax cases by agegroup in 4 weeks Dec-Jan with vax cases. What do you notice?

13/ what stuck out for me: the age composition of unvax cases is totally different than age composition of vax cases. Unvax cases in UK are overwhelmingly under 30, while majority of vax cases are over 50, with very large number of 70 and even very vulnerable over-80s.

14/ so there are two related but somewhat different things going on: a rapid resurgence of COVID among vaxxed seniors and an explosion of cases among unvax young people.