I'm going to do a thread on sums in a pandemic and vaccine uptake and infections.
It's hot so forgive any typos in advance.

A fictional population of 1000 people. Vaccine uptake of 80%, so 800 vaccinated and 200 not.
Vaccine is 80% effective in preventing infection.
Transmission increases and all those unprotected get infected.

That's the 200 unvaccinated and 20% of the vaccinated, that's 160.

So looking at the infections it would look like 55% are unvaccinated and 45% are vaccinated.
Does it mean we panic and say that the vaccines don't work?

No, we do not.

In this example 100% of those unvaccinated got infected, only 20% of those vaccinated did.
In real life the numbers can be even more equal or there can even be higher numbers of vaccinated cases than you would expect from the vaccine efficacy.

This is because higher risk people are vaccinated first, including those who might not mount a protective immune response.
So in summary, it's also good to compare the numbers within the group.

What % of vaccinated are cases as well as what %of cases are vaccinated.

I might have confused you all at this stage!

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More from @marietcasey

19 Jul
I think it's really important to look at our daily numbers and realise

1. Diagnosed infection is always the tip of the infection iceberg, our true daily rate is a multiple of that.

2. Younger people are the unvaccinated ones and are also likely to have fewer/no symptoms.
What critical is how the case numbers relate to hospitalisations/mortality. We will know more in the coming weeks and be able to learn from our neighbours.
As numbers go up contact tracing will not be able to meet demand, there's always a ceiling to that capacity.

In fact though, when community transmission gets that high, containment measures like that are far less useful.
Read 6 tweets
17 Jul
I'd also like to talk about some good examples I've heard from businesses in relation to the Covid vaccination programme.
An employer asking their admin staff to help register their staff for immunisation if they wanted help. Actually including this in their work day.
An employer sending out an encouraging letter a while ago, saying they supported the programme and any employee attending the vaccination appointment could have a paid half day off for it.
Read 7 tweets
17 Jul
Let's talk about employees being allowed to leave during working hours to attend their Covid vaccination appointment.

I think this is utterly critical that this is facilitated.

Every cancellation/rescheduling slows the vaccination programme or risks vaccine waste.
It is hugely beneficial to a company to do this, shows a duty of care to their employee and protects their busines from outbreaks. It is a no brainer.
There is a lot of confusion out there and it's evident to me that there are a few things going on.

1. Companies haven't formally decided that this is their policy.

2. If they have they haven't communicated it properly to managers and employees alike. It needs to be in writing
Read 6 tweets

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