A brief summary of the very precarious situation we are in now, and why we have a very narrow window to act in the UK. If we don't act now, it's likely the window for containing COVID-19 will pass- not just for the UK but globally. Here's why. Thread.

The UK is home to a new variant strain of virus- one that's thought to be ~56% more transmissible than the previous strain of virus. This viral strain continued to spread through the previous lockdown, where cases were rising in London & the SE England even under lockdown 2/N

This means even with national lockdown, surges of cases will be very difficult to control. It also means we will need much higher vaccine uptake ~90% or even more to achieve an R below 1 - if this is possible at all (given we don't know the vaccine efficacy on transmission) 3/N

While many countries closed borders with the UK, the UK has already exported the more transmissible variant to many parts of the world - including Europe, India, S. Korea - much of the global pandemic trajectory will now depend on how well these outbreaks are contained. 4/N

The UK did not act urgently enough to contain spread of the variant, both within the UK, and across the globe. This means that it is possible that this variant will become dominant in many parts of the globe, given gaps in surveillance, which hamper efforts to contain it. 5/N

If the variant spreads to other regions, it will likely become the dominant strain rapidly, given the higher transmissibility. Worryingly, we are also seeing other independent strains with overlapping mutations emerge in other parts of the globe that also seem more transmissible

This really highlights the potential for adaptation of the virus. This isn't the first strain we've seen that's more transmissible. Earlier this year we saw the D614G viral strain become dominant across the globe- which was shown to be ~20-30% more transmissible.

B117 mutants have now emerged *on top of* this background and appear to be even more transmissible. The recent PHE report suggests an increase in secondary attack rates from ~10% to 15%. A rise to this extent can make spread much easier, even with mitigatory measures in place 8/N

What does this mean for pandemic control measures?
The virus is unlikely to be controlled with lockdown without controlling school transmission. @IndependentSage has recommended school closures until schools are made safe, as many have been recommending for months. 9/N

The government doesn't seem to have a long-term plan for schools. The 'mass testing' programme appears to be directed only at contacts of cases - to decide on whether they need to isolate or not - rather than detection of new cases. This will not control school transmission 10/N

The govt has repeatedly said it's prioritising education, while it's policies have directly led us to a point where schools now need to be shut down because we have done little to curb transmission in this setting & have also not invested in remote teaching in schools. 11/N

Along with reduction in school transmission, we also need we need rapid vaccine-roll-out and high uptake. However, currently we are behind the target of 2 million/wk of vaccination - as @IndependentSage suggests, this needs much greater investment in local authorities.

The fact is that we are now at a point where we are almost saturated in terms of measures we can take to contain COVID-19. Lockdowns that would have had a greater impact before have much lower impact now. We need much higher vaccine coverage & we may not achieve control then

Zero COVID could have been achieved, as many countries did earlier on. High levels of transmission favour viral adaptation, which we knew about in Feb. We not only squandered the opportunity for elimination then, we're also responsible for exporting the current strain globally.

Global spread of this variant will scupper pandemic control worldwide & cause hundreds of thousands more deaths.

Really worth reading this thread by @AdamJKucharski that shows the impact of a more transmissible on fatality due to exponential rise. https://twitter.com/AdamJKucharski/status/1343567425107881986?s=20

We have a very narrow window to contain this in the UK, & globally. We need to seriously act to eliminate. Suppression with continuing transmission is not an option- for the UK or globally. We must act collectively to stamp this out.

If we don't, there is little hope of containing this in the future. It's very likely that we will see more adaptations of the virus if transmission continues (give we have already seen this happen, it is likely to happen again). We can't afford this.

We have little capacity to increase our response to the virus, given the high level of transmissibility that makes lockdowns less effective, and raises our herd immunity threshold substantially. This is our last chance. We must grab it with both hands, and act aggressively.

And school transmission is key. Models largely look at opening & closing schools, as if these are the only options that are available. Let's act to curb transmission in schools now, by making them as safe as possible. This is the only way forward. Anything less is negligence.

And 'hang on until vaccination' is a deeply negligent strategy. Our hospitals are at capacity *now*. We are seeing >40K confirmed COVID-19 cases/day. We can't afford to wait. And let's remember that vaccination will not necessarily bring an end to this.

Given the high levels of uptake needed, and the fact vaccines aren't even licensed in children yet, and we don't know the efficacy on reducing transmission, we cannot count on vaccines alone. We need a multi-pronged approach to eliminate.

And high levels of transmission in a population that's being vaccinated will also increase the probability of escape mutations emerging from selection pressure due to vaccination. There are so many reasons to eliminate this. Vaccination is not the end. It's only a part of this.