Herd immunity strikes back

With a bit of a shock and disbelief, I have read a new article in the Financial Times titled: UK scientists call for debate on allowing ‘big wave of infection’.

The article describes the idea that once all potentially vulnerable people are protected by the COVID-19 vaccine, we should allow the disease to run through the young population to achieve “natural” herd immunity. The title is a bit misleading as it is not scientists who are proposing this (at least not scientists mentioned in the article, like Mike Tildesley or Graham Medley, both of whom I highly respect), but politicians.

It is an interesting adaptation of the Great Barrington Declaration idea, only this time it uses the vaccination as the method to protect the “vulnerable”. There is a good discussion of the downsides of the GBD strategy on the COVID FAQ web site and the arguments there – particularly points 4-7 – stand whether the protection is achieved by locking down only the “vulnerable” parts of the society or by vaccinating them.

Whatever the arguments against this strategy, I am quite pessimistic about future developments. I suspect that unlike the original GBD proposal, the current one will gather a lot of support and – willingly or not – governments – and societies – will be tempted to go down that route.

Why is it so? I think that the societies in many countries including the UK and my native Poland are reaching a breaking point. The first lockdown was generally very successful in bringing down case numbers and it was generally broadly accepted and obeyed. I am still amazed at how rapidly and deeply the Google mobility data dropped back in March/April.

However, most countries (except Australia, New Zealand, Taiwan and similar) were not really focusing on zero-COVID approach. Fearing the economic meltdown and once the threat of health system collapse disappeared, the governments opened up. It all looked very rosy – the pandemic is (almost) under control.

We now know pretty well that Scotland almost eliminated the virus in summer 2020, only having it reintroduced later. The similar situation appeared in many other countries. The second and third waves came, with new, more infectious strains. But more importantly, the lockdowns came late, never really reached the depth of the first one, and were relaxed for Christmas and New Year.

While in most places the first lockdowns were painful, but simple and short, the second ones tended to be complex. Attempts to keep parts of economy going resulted in complicated rules. People stopped understanding why this part of the economy or social life is closed and the other is not. The economically vulnerable started feeling the pressure and essentially stopped obeying.

As the governments botched the response in mid-2020, they created a situation where more and more people, for different reasons, feel that the lockdowns do not work and should be abandoned. Trying – rightly – to convince more people about the merits of vaccination, we also created a conviction that vaccination will solve all problems. It will not, but it does not matter – the message is there.

So what are my expectations? The end to lockdowns followed by a large spring wave which – in contrast to the first one – will largely affect young people. Hopefully, there will not be too many hospitalisations and deaths but I doubt this will be the end of the virus.

Is this the best solution to the pandemic? Absolutely not; it is my firm belief that the optimal solution would have been an early, sharp, deep lockdown to bring the numbers down, followed by strict test-and-trace with extensive support for people who need to self-isolate, and strict border control requiring tests and quarantine.

On Astra Zeneca vaccine and statistical trials

I have just been reading an excellent blog on statistics with the most recent articles on statistical aspects of vaccine efficacy trials. I am not going to repeat the full analysis and invite you to read it if you are into statistics. It is very well written and explains difficult ideas very well.

If I follow the author’s argument, essentially the Astra Zeneca trial is an example of how not to carry out a highly sensitive vaccine efficacy trial.

While I do not think the author of the blog actually says that there is something wrong with the AZ vaccine, but he presents a very compelling story on why the AZ claims are not supported well by the evidence.

It would have deserved just a note in statistical textbooks, where it not for the fact that the consequences are important for our health. How much protection does the first shot give? Is it OK to delay the second shot? It might all be OK, but sloppy evidence undermines the message.

Great resources

Just a short note to bring to your attention some excellent resources:

  1. The Johns Hopkins University web site not only hosts one of the key data sets for COVID-19, but also a series of articles explaining different aspects of the pandemic.
  2. The Our World in Data website again not only hosts one of the “definite” data sets of the pandemic but also has an excellent front end showing very nicely presented graphs.
  3. A new website covers topics like The Great Barrington Declaration and similar claims.
  4. Another blog post, from The BMJ (formerly the British Medical Journal), responding to many conspiratory views about COVID-19.

Enjoy reading!