NEW: B.1617.2 is fuelling a third wave in the UK, with not only cases but also hospital admissions rising.

Vaccines will make this wave different to those that have come before, but it remains a concern, and one that other countries will soon face.

Thread on everything we know:
First, cases in the UK.

It’s been clear for some time that B.1.617.2 has been driving local outbreaks in North West of England, but data suggest it’s now far more widespread.

By mapping sequence prevalence onto total cases, we can see how the new variant is behind recent spikes
If we plot B.1.1.7 and B.1.617.2 on a common baseline, most areas show a shrinking outbreak of B.1.1.7 alongside a growing one of B.1.617.2.

What looks like "cases are flat", is probably "one going down, other going up, and it has more room to grow than the other has to shrink".
Two things to note at this point:

First, it’s not clear everywhere will follow Bolton, Blackburn, Bedford. They absolutely could (and 👀 Rossendale), but it’s also possible conditions in those areas favoured more rapid spread than elsewhere.
For example we know Bolton’s outbreak initially flared in neighbourhoods where vaccine uptake was moderately low. Pointing this out is not to blame individuals, but to demonstrate how local contexts matter in outbreaks.

Other areas e.g Sefton saw spikes become bumps.
Second thing to note, and first sign that vaccines will fundamentally change this wave:

Case rates are staying low among older, mostly-fully-vaxxed age groups

No indication this pattern is changing, and it supports evidence from @PHE_uk that two doses stand up well to B.1.617.2
And this really matters when we move onto the more critical metrics, like hospital admissions and deaths.

If you have two waves of cases of equal volume, and one has a much younger age profile, it will result in much fewer deaths.

We can use Bolton to illustrate exactly this.
Since April 1 there have 3,387 cases in Bolton. In the same length of time during last autumn’s wave, there were 3,386

But while last year 3,386 cases became an estimated 35 deaths, this year we can use age-specific-CFRs to estimate they will result in 9 deaths. A 75% reduction.
You can see the driver of that difference in expected death rate more clearly if we look only at older groups:

Although we’re looking at two periods of 3,386 cases in Bolton, the latter has far fewer cases among the elderly. 75% fewer cases among over-80s, the most vulnerable.
So the same number of cases but 75% fewer deaths, because vaccines are keeping [most of] the elderly out of this wave.

(A big thanks to @VictimOfMaths for giving my maths a sanity-check in those calcs, and to Daniel Howdon whose age-specific CFRs I used).
And it’s also worth plotting that same data for the whole of the second and third waves last year for Bolton:

The signs are that Bolton’s current outbreak is near its peak, whereas last year it was only just getting going.
Nonetheless, protecting the very elderly is only half of the battle.

Even though fatality rates are much lower for younger people, if large numbers of younger people get seriously ill, a small percentage of a large number can still cause lots of hospitalisations and some deaths.
And the data now show that hospital admissions in the UK are indeed rising. Admissions have risen by 20 per cent across the UK as a whole in the last week.

In the North West that’s 25%, and in some other regions including Scotland it’s higher still.
If we zoom in to Bolton, we can compare the recent rise in Covid hospital patients to the second wave.

That early rise looks very similar, though I would caution that last year rates kept climbing for months, this time with cases now no longer increasing that’s very unlikely.
But as with cases, it’s not enough just to look at total trends, age breakdowns matter with hospital admissions too.

And again here we see signs that this wave is not like previous waves. Thus far the rise in admissions in the North West has come exclusively among younger people
Of course, no hospital admission is a good hospital admission, and if hospitals become too full, quality of care and outcomes suffer, regardless of age.

But so far, the age profile of admissions looks promising and would again suggest a much lower fatality rate for this wave.
So in summary:
• B.1.617.2 has sent cases rising again even in a country with very good vaccine coverage
• But vaccines are keeping cases and hospital admissions largely among the younger age groups whose risk of deaths from Covid is much lower
To be clear, this is not a "so everything’s fine!" thread.

Everything is not fine, and with hospital admissions rising again it’s clear the reopening roadmap needs to be re-evaluated.

But this wave is not like the other waves, and it’s important to keep that in mind.
Finally, I said other countries will soon face this challenge.

B.1.617.2 is already dominant in India & UK (and many other Asian countries where sequence data is lacking), but prevalence also climbing fast in US, as well as many European countries.

(HT @TWenseleers for method)
What we’re seeing in UK is very likely to show up in other Western countries soon. This thread is a sign of what may come, but also a call to vaccinate, fast.

Vaccines are already making UK’s third wave less lethal. With enough jabs in arms, next country could fare even better.

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More from @jburnmurdoch

23 May
A side note: I’ve seen it said that the media is putting a positive spin on things despite SAGE members and other experts being much more worried.

This is a surprise to me, since the people we speak to for our reporting and quote in our articles are SAGE members and experts 🤔
We probably spent 20+ hours each reporting these stories, running well into Friday night and Saturday. This involved speaking to experts in immunology, epidemiology and broader public health, including the very people who did the analysis on vaccine efficacy and transmissibility.
I get why some think there’s not sufficient alarm. 150k have died in the UK, and a reluctance to act early has played a part.

But to accuse us of spinning when we’re working our asses off to get data & expert comment to the public as quickly as possible, is quite something.
Read 6 tweets
23 May
Lots of questions still bouncing around on vaccine efficacy vs B.1.617.2, so here are some follow-ups to our Saturday morning story:

Thread follows, and @SarahNev and I published a new story last night covering all the details including transmissibility:…
Following our original story, PHE later published more detailed data disaggregated by vaccine.

That data shows our pooled figure of 7% relative drop in two-dose efficacy against B.1.617.2 vs B.1.1.7 comprised a 6% drop for Pfizer, 10% drop for AstraZeneca. Very little difference
Similarly, the 35% relative drop in efficacy after one dose was virtually indistinguishable between the two vaccines.
Read 21 tweets
22 May

Public Health England has presented the first real-world data on vaccine efficacy against B.1.617.2, the variant first found in India.

Efficacy against symptomatic B.1.617.2 was 81% after two doses, much higher than many have feared.

I would ask people to read what follows carefully. Vaccine efficacy is a nuanced topic and the numbers here need to be interpreted in their proper context.
The data, which the FT has seen, suggest first dose offers around 35% less protection against symptomatic infection with B.1.617.2 compared to B.1.1.7, but after two doses the relative drop is only 7%.

The figures are based on pooled data from the Pfizer and AstraZeneca vaccines
Read 15 tweets
20 May
Just two quick charts on B.1.617.2 today:

Cases continue to climb in Bolton, Blackburn & Bedford, (known B.1.617.2 hotspots), though rate of acceleration in Bolton has slowed slightly, and test positivity there is flat, suggesting surge testing is playing a role in 📈
Continued increase in those areas would be a concern, and it’s worth noting rises in neighbouring Bury and Burnley too.

B.1.617.2 not believed to be dominant in either of these areas, but Sanger data is now 12 days old so that may have changed.
Nonetheless, the same chart shows that high prevalence of B.1.617.2 is by no means a guarantee of prolonged resurgence.

Hounslow, Nottingham and Sefton are all places where B.1.617.2 is believed to be dominant, and yet their upticks reversed and now appear as brief blips.
Read 8 tweets
17 May
NEW: latest update on B.1.617.2 in UK



First, today’s Sanger data on variants at local level. On the surface, this doesn’t look good. Cases of non-B.1.617.2 are in decline, but those red peaks are the variant sending overall rates climbing
To state the obvious: that pattern is not what we want to see, and if things keep going in that direction, we could see national cases rapidly climb again.

But there are a couple of reasons to pause before assuming we’re going to see those peaks steepen and proliferate.
First, the Sanger data is sequences with specimen date before May 8.

We’ve got more days of data since then. It’s not broken down by variant, but it can show us what’s happened to total cases in those areas since May 8.

Answer: growth rates have slowed, in some cases reversed
Read 18 tweets
16 May
Good, measured thread from @JamesWard73 as ever.

If B.1.617.2 does prove to be more transmissible, we may need to keep things like indoor masking and tests for entry to large events for a while beyond June 21.
My thoughts:
• No, that wouldn't mean "lockdown never ends". No, it wouldn't be curtailing freedom. It would be a very small compromise for a very large benefit
• As vaccination rates continue to climb further into the year, those few remaining measures could then be eased
• It's still entirely possible any transmissibility advantage will prove to be much smaller than some have estimated. In that event, June 21 plans can proceed as planned
Read 4 tweets

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