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Some momentous developments

A report came out recently suggesting that there is a large variability in the levels of antibodies to COVID-19 and that they tend to disappear in a matter of days and weeks. This has been reported in this preprint and that preprint so it has not gone through all checks. But it agrees with some other evidence, discussed here, that patients can indeed get the virus twice. There are now more studies pointing in that direction, and indeed, the similarity of SARS-CoV-2 virus to other coronaviruses would suggest that the immunity might not be long-lasting.

If this is true, it has some very serious consequences. It would mean that the whole idea of “herd immunity” is not valid in the long run. It would mean a collapse of the Swedish strategy which also – despite all contradictions – appears to be the British way of dealing with the virus. If indeed SARS-CoV-2 is more similar to a common cold than to flu, we do indeed need to learn to live with the virus for a long time.

On the positive side, a serology study which looked at both exposed and unexposed individuals found a large variety of immunological responses. If I understand this study correctly (and I am not an expert in immunology), many individuals who have never been exposed to SARS-CoV-2 are showing an immunological response. In fact, they claim 81% do.

Again, if this is true, it suggests three things. Firstly, the tests are likely to show a lot of false positives. In other words, if somebody is tested and gets a positive result, it does not mean this person was exposed to SARS-CoV-2.

Secondly, and related to my point about the short-lasting immunity, even if a person was indeed infected, there is no guarantee they are immune. Thus, any idea of “immunity passports” is irrelevant.

But thirdly, perhaps there is actually a high – although not as high as 80% – the general level of resistance to the virus. Perhaps the epidemic will indeed slow down soon and the virus will become a nuisance (like a common cold) rather than a deadly enemy.

In the light of these findings, I marvel about the complexity of creation – and about the peculiar beauty of viruses and the ways our bodies deal with them.

But also a word of warning. As I said in my article in The Conversation about the herd immunity, politicians often get fixated onto simple concepts – like “herd immunity” – which are in fact not simple at all.

24 weeks

I have been reminiscing about the pandemic today and looking at the calendar. Just over 24 weeks ago (31st January), the first UK case was detected, followed 4 weeks later by the first COVID-19 case in Scotland (1st March) – 20 weeks tomorrow.

My thoughts were drawn to this early days by the article in Financial Times, titled Inside Westminster’s coronavirus blame game, published on 16th June. It is a very interesting piece, not only from the political of view, but also because it discusses in great detail the thinking behind the decisions taken at that time. It talks primarily about the critical week of 16-23rd March, just before the lockdown, but when the UK government was apparently abandoning all testing and appearing to do very little.

But things were already getting out of the government hands. My last day an the uni was 10th March, as I was working at home on the 11th and attended a conference in Edinburgh on the 12th. University closed down on the 16th and the full lockdown started on the 23rd. There were nearly 13 thousand cases reported in the UK by then. Nearly 300 thousand have been reported since.

I noted that my first blog on coronavirus appeared on 12th March and included these lines:

You need to understand that a politician needs to carefully balance the pros and cons of any action they take, as the consequences might be massive. This means that they tend to either do nothing (President Trump before the 11th of March) or go into a full action (President Trump after the 11th of March). They will not want to be accused of needlessly spending money. Still, on the other hand, they do not want to see TV programmes about hundreds of people dying in hospitals. In fact, our own research shows that for people, there are two rational strategies, do nothing, or act with a full force. Economists call it a ‘bang-bang’ approach.  So, expect the governments to swing between different options as they face the biggest crisis since 2008.


With a bit of a Schadenfreude, I note that the next 20 weeks have illustrated very well the approach to coronavirus, not only of the UK government but also worldwide. Even now, the UK government is encouraging a full return to work, as if the virus has already gone having changed the strategy from a deep lockdown to a full “normality”.

Do I still think the early lockdown was the best thing to do in March? I probably still do think that the government should have acted sooner and stronger, and I regret not having spoken then, not having written to the MP, or to the press. It probably would not have made any difference (I am not part of SAGE, or any similar advisory body), but I would have had a satisfaction of having done something right.

What I certainly did not expect then was how well the UK population would obey the lockdown once it was announced. Google mobility data show that the UK had one of the deepest reductions in mobility, although there is some evidence that the local scale (village, street) mattered more than the country level. Perhaps an early lockdown could have arrested the disease spread better than the late one (as in New Zealand, or South Korea), would have lasted shorter and costed less.

Or, perhaps, the Swedish model, with a partial lockdown and reliance on the voluntary social distancing, but better done, with a much higher protection of the vulnerable population (elderly, care homes, immigrants), would have been a better solution.

Mathematical epidemiologists really need to have a serious discussion with economists, something that has not been done too well over the last months. This will allow not only evaluation of what could have been done, but – more importantly – how to deal with the ‘winter wave’ if or when it comes, or with the next big pandemic, when (not if) it comes.

The article in Financial Times makes it clear that one of the problems faced by the government and SAGE in March was that they were all expecting a different epidemic. The next time, we need to be better prepared.

Herd immunity

A new article on “herd immunity” is now available in The Conversation. It took me a couple of weeks plus quite a lot of research into history and different aspects of this concept. There is also a more technical article available on this blog. I am also hoping that at some point there will be an online tool to explore simple models of herd immunity; an extension of the model for the second wave.

I was particularly keen on getting the last section right. Herd immunity is a very powerful concept, but also one that is badly misunderstood and dangerously misapplied.

At the end of the day, it is about a potential conflict of interest between an individual and the “herd”; something that can possibly be resolved, but only in a very careful way. This is particularly important for vaccination and I understand where (at least some of) the opponents of the mass vaccination programmes come from. But this is probably a topic for another story, another day.