Richard North, 08/04/2021  

Given that prime minister Johnson is a congenital liar, it doesn't strike me as particularly helpful for him to make a public declaration that the AstraZeneca vaccine is "safe".

Even if Johnson had an unsullied record for telling the truth, however, one would still have to question him, or anybody else, who made assertions as to the safety of a vaccine, in absolute terms.

Only for children is safety an absolute – for adults, safety is a relative term, assessed either intuitively, based on experience, or as a precise quantum, reflecting the likelihood of an adverse event occurring.

Clearly, vaccination involves risk but, the probability of being harmed appears to be very low – which would suggest that there should be little concern about exposing oneself to the risk.

However, there is another element to take into account: the risk-benefit ratio. To taker one extreme. If the benefit is very great – such as saving the subject from certain death, then one can tolerate quite a high level of risk, even if the adverse even might be serious.

Needless to say, though, things are rarely that simple. For the vaccines on offer, even the AstraZeneca product, in global terms, the benefits are high and the risks are very low. For instance, the UK reports a mere 79 blood clot cases from the AZ vaccine out of 20 million vaccinations, of whom 19 died.

That, of course, doesn't make the AZ vaccine "safe". Rather, it can be deemed safe enough for general use. But then, there is another factor to consider. The risk-benefit ratio is not the same for all ages. The chances of suffering a fatal blood clot a higher in the younger age groups. In particular, 18-29 year-olds have been cited – and it is this group which has a low risk of suffering serious harm from Covid-19.

On that basis, the question of safety, per se is actually an irrelevance. Clearly, the product is not "safe" in absolute terms. But what matters is the risk-benefit ratio. And, for the particular group, although the risk of harm is relatively low, it is not insignificant. On the other hand, for that group, the specific benefits are also relatively low.

Perversely, that suggest a relatively slender risk-benefit ratio for the group in question. The Guardian is suggesting that people within the 20-29 age group (with low exposure risk) have a risk of 0.8 per 100,000 of being admitted to an ICU compared with a 1.1 per 100,000 of suffering harm from an AZ vaccine.

Clearly, on the basis of those figures, the balance of advantage is in not being vaccinated. On the face of it, any individual within that age group might not be unreasonable in questioning whether they should have the AZ vaccine.

To add layers of complexity, there is yet another factor. One might have to assess whether individuals in that group who accept the vaccine might be conferring a benefit not on themselves, but on other age groups – one that, for the moment, can't even be statistically calculated.

That then, is asking individuals within the group potentially to sacrifice themselves for others, taking a known, albeit small risk for an unknown benefit to person or persons unknown.

All this makes Johnson's blather particularly inappropriate. He is cited as saying that the current (updated) advice on vaccination "should allow people of all ages to continue to have full confidence in vaccines, helping us save lives and cautiously return towards normality".

But only slightly more than a week ago, when Germany was making moves which would have the effect of all but banning the AZ vaccine, many British media sources, not least the Express, were lambasting Angela Merkel for "over-reacting".

Later, as Germany was joined by France and Spain, in scaling down the use of the AZ vaccine, The Times was ponderously reporting that the EU's medical regulator has said there was "no evidence" to support their decisions by to stop using the AZ vaccine on younger adults because of concerns about a rare blood disease.

Much mileage was made in certain quarters about the risk-adverse Europeans who were apparently failing to understand the concept of risk benefit. Even the New Statesman was moved to question whether Europe was misapplying the "precautionary principle".

International correspondent for the magazine, Ido Vock, suggested that the reason these timorous continentals were suspending use of the AZ vaccine what that "some governments still don't know how to calculate risk during a pandemic".

"Most of the governments that have halted the use of AstraZeneca", he wrote, "have cited the 'precautionary principle', a concept in some EU policy which states that precaution should prevent potentially harmful actions being taken 'even before a causal link has been established by absolutely clear scientific evidence'".

And yet, it would seem Vock and his ilk have not read the Commissions own instructions on the use of the precautionary principle. The principle, it says, should be considered within a structured approach to the analysis of risk which comprises three elements: risk assessment, risk management, risk communication.

The precautionary principle, the Commission counsels, is particularly relevant to the management of risk. Essentially used by decision-makers in the management of risk, it should not be confused with the element of caution that scientists apply in their assessment of scientific data.

Recourse to the principle presupposes that potentially dangerous effects deriving from a phenomenon, product or process have been identified, and that scientific evaluation does not allow the risk to be determined with sufficient certainty.

The implementation of an approach based on the precautionary principle should start with a scientific evaluation, as complete as possible, and where possible, identifying at each stage the degree of scientific uncertainty.

But, it says, decision-makers need to be aware of the degree of uncertainty attached to the results of the evaluation of the available scientific information. Judging what is an "acceptable" level of risk for society is an eminently political responsibility.

Decision-makers faced with an unacceptable risk, scientific uncertainty and public concerns have a duty to find answers. Therefore, all these factors have to be taken into consideration.

Having applied this principle myself in a professional capacity, I've come to the view that it is one of the clearest enunciations of the principle yet published, and infinitely preferable to Johnson's boosterism.

One recalls the days when that noted expert Rod Liddle was intoning that "If you ever needed a reason for Brexit, the EU's coronavirus vaccine stupidity is it".

Writing in The Sun, this "expert" told us that we might have read that "a bunch of European countries have suspended use of the AstraZeneca vaccine because some people who had them later developed clots. And some died from them". The number, says Liddle, is about 37 out of 17 million.

"This", he intoned, "proves to me a few things. First, that politicians just do not understand statistics and risk. Especially French and Slovenian politicians. Second, that the EU is still riven with a hatred and enormous envy of the UK right now".

Three weeks later, things look a little different with the UK's joint committee on vaccines and immunisation (JCVI) suggesting that healthy 18- to 29-year-olds should have the option of a different jab if one is available in their area, effectively sending the UK down the path already taken by the hate-ridden Europeans.

One suspects, though, that Rod Liddle and his fellow-travellers will not be revisiting their earlier copy. That would require them to admit error, something they could not possible do.

Also published on Turbulent Times.

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