Will the UK have a 3rd wave of COVID?

In the UK, Covid-19 cases are now very low, helping to unlock the next step on our lockdown-easing roadmap; many of the adult population celebrated the return of former freedoms at newly-reopened pubs, raising a glass in the process to the fact that 32 million people, more than half the population, have so received a dose of vaccine: one of the highest rates in the world. Meanwhile, cases continue to surge across Europe, and in South America and India, in what many are calling "the third wave". Since early in the pandemic, Kings College London's Tim Spector has been following the course of the outbreak and monitoring its trajectory with the Covid ZOE app he helped to develop and which has generated large amounts of data and insights into the activity of the new coronavirus around the country. So does he think we're in for a third wave as we open up?

Tim - No, not this summer and probably not this year. I think we might have a ripple at the end of the year, as the immunity wanes and we get cold weather again, but I'm not seeing what we would now consider a third wave, in my estimation.

Chris - Why are you at odds with what a lot of people - a lot of eminent people - have been saying is the likely outcome from our present situation? And also with an eye on what's going on in Europe - of course they're experiencing what they're dubbing the 'third wave'.

Tim - Well, the 'third wavers' have been relying on modelling, which is always based on a number of assumptions. The data we're seeing from the ZOE app is much more reassuring than a lot of those assumptions, in terms of: the efficacy of the vaccine, in certainly preventing cases, is much higher than was predicted in a lot of those models. And so that's the reason, I think, we have got our case levels so low; this week they're down below 2000 cases a day where we were back in July last year. It's that detail about the vaccine, that we're seeing... even after one shot we're getting 50% less cases, and after two shots we're getting 15 times less cases. That's the thing that heartens me, that we are progressively moving towards herd immunity. That's why I don't think variants - whether they come from abroad or inside - are going to be able to take hold this year.

Chris - Last week, University College London put out a paper suggesting we were about to cross that magic threshold, that had been proposed as a target to achieve some semblance of herd immunity: in other words, the number of people as a proportion of the population that are immune. Do we actually know, though, what fraction of the population need to be immune to stop this thing spreading?

Tim - Estimates seem to be somewhere between 50-75%. So the fact we're at 60% vaccinations, and there's probably another 10% of people that have got antibodies, suggests that we're pretty close to that.

Chris - I wonder why the Prime Minister earlier this week, then, was at pains to say: this is the effect of the lockdown - don't read too much into the vaccines yet. Is that just really to stop people going off on a bender because the pubs are open again?

Tim - His comment doesn't really make sense to me, looking at the data, because when lockdown came, we'd already seen the peak in most of the country. I believe that the lockdowns have helped - social distancing and reducing mobility absolutely helps - but there's no doubt that the vaccine has been really much more effective than people thought it would be in real life. And we've got a paper coming out in a week or so to show that. It's broken the cycle of infections in hospitals, and in care homes, that plagued this last year. I think it's made a real difference this time. And so outbreaks really can't gain hold because there just aren't enough susceptible people.

Chris - What about the issue of variants though? Because we saw the dramatic impact of the appearance of the Kent variant, when it first popped up on our radar screens back in September, and then eclipsed everything in the country by Christmas. What about the possibility of a new variant coming in - either from one of the other countries being ravaged by coronavirus at the moment, or just popping up spontaneously within the circulating viruses we already have in the country?

Tim - Well, I think we definitely will see new variants. I think everyone's agreed on that. The question is: is that variant going to be dominant enough over the other strains to take over? And if it has fought off the other strains, does it have the ability to fight off previous immunity or the vaccines? Really, there's no hard data to say that any of these strains do anything more than slightly reduce the efficacy of the current vaccine. So given there are so many 'ifs', there's no reason that we should stop all our plans to come out of lockdown, because I think they're getting increasingly remote.

Chris - Is that true though? Because if one looks at Brazil, as one example, people are suggesting that if you look at, say, the P1 variant that popped up in Manaus: in that part of the country last year, the number of people hit by coronavirus initially was at least 70-80% of the population. That same area is being hit again by this new variant, which appears to be bypassing the immunity those people naturally had, having been infected previously. So does this not argue that actually, if a new variant - including the Brazil variant - pops up here, we are potentially in trouble and back to square one?

Tim - If that is entirely true, then I think there would be cause for concern. But I think whether that is the actual case, and whether the data in Brazil about what happened previously is really good enough, I'm not so sure. The likelihood that a new strain would come in and take over a complete, currently-immune or previously exposed population to such an extent that it caused a major third wave, I just see as still very unlikely.

Chris - Is it not a serious concern though, that if we do send our population off on holidays to countries where there's a partially vaccinated population, this is the ideal breeding ground for the kinds of mutants that could infect vaccinated people, so therefore the only coronavirus people are going to come back with is one that can bypass immunity from the vaccinations, and then we'll spawn new outbreaks here?

Tim - I think that's a possibility, but it's a question of weighing up the bigger picture - the economic picture, and the psychological picture - of whether we want to lock down as an island for several years like New Zealand. That's the alternative. One of the key questions here is: do fully vaccinated people really transmit the virus in enough numbers to be a worry and bring it back? And I think that's the killer question. And depending on that, then vaccinated people are more or less free to travel as they want.