It's an interesting question and one without an easy answer but if you look at the heatmap from @PTHBhealth you can start to get an idea of what is going on, Thread on #COVID19 in Powys ...
First up, the heatmap itself, this is simply a grid of infection rates per 100k population shown in different age ranges and in different weeks. This map covers the period from the start of the school holidays to 10 days ago. So what does it show.
First up you can see particular events in this instance two outbreaks in care homes which can alter trends in the data but what you can also see here is the steady growth of infection in the over 80s to about the 19th Sept
This then goes into a very dramatic reverse against the trend in other age groups as the booster vaccine programme kicks in
Next look at the decline in infection in the 20-30 year olds and how this has largely been maintained despite rising cases elsewhere. Again a clear indicator of vaccination.
Then look at the under 19s. Only the most vulnerable have been vaccinated in this group until the past couple of weeks so this is what Delta would have looked like in an unvaccinated UK. Despite starting Aug at a comparable rate the two group immediately diverge...
As vaccination suppresses the infection in the 20+ group the dereliction of duty by JCVI leaves the under 19s at the mercy of the virus with infection rates increasing to the point that there is now a 5fold difference in the groups.
Finally 30-50 and 50-70. The older group shows a slow but steady rise likely reflecting a small waning of vaccine and wider community transmission rates. In contrast the 30-50 group shows a steady increase about 2 weeks behind teenagers indicating possible household transmission.
So the heat map shows clear age and vaccine-related drivers to rates of infection. With rates amongst the unvaccinated significantly higher than those with a vaccine. Waning is also present as is the impact of the booster. Is anything else at play?
The first thing to remember is that Powys has had very low rates of infection across the whole pandemic. This means that we are much more reliant on vaccination to provide immunity. This means we have a disproportionately large pool of children with no immunity compared to others
The result is in the past 21 days parts of Powys have seen very high infection rates compared to other parts of Wales. But also notice the variations across the County.
Given the age range of infection and this pattern, it is possible to hypothesis that the major drivers are....
➡️Infection of school children esp high school ➡️School based infection as a driver ➡️Staff also affected ➡️Household transmission to parents - siblings ➡️Mittigated by recent vaccine uptake and boosters
How can we break out? ➡️Increase mask-wearing indoors ➡️Limit mixing across high schools at half term ➡️Meet up outside for activities when you can ➡️LFT before going to any event or place of gathering And finally ➡️Extend half-term to 2 weeks to maximise vaccination potential
What are the risks? ➡️Early vaccination and high O-AZ use means we are at risk of vaccine waning sooner than others. ➡️Complacency - historically low rates mean we are relaxed about risk ➡️NHS overload - Flu cases plus Covid Case = overload of ICU capacity?
➡️Mutation - AY.4.2, a delta subtype, is 10-15% more infectious than Delta in early tests and is now 10% of UK sequenced genomes. This could increase transmission and hence increase breakthrough cases in the vulnerable.
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