From what we read and hear lately, it seems that a large part of the population considers vaccines to be more of a miracle than a medical-scientific product. In this regard, it has been reported that tens of thousands of people have not been vaccinated in recent days with the AstraZeneca vaccine, and although this is a somewhat logical reaction after the doubts and changes in criteria shown by the political decisions, it brings little consolation to such nonsense.
The fruits of religion are usually either absolutely good or absolutely bad, e.g. miracles in the first case, demons in the second, which often does not mean much either, given the rather imaginary and ungraspable character of the matters of religion.
Medical-scientific products are the fruit of human knowledge about the laws of nature, and follow the scientific method (a reasoned theoretical approach that must continually confront the experimental evidence). The process of scientific discovery is complex, difficult, full of nuances, of comings and goings, and therefore not prone to the Manichean simplification typical of religious questions. Our scientific understanding of life in general, and human life in particular, has improved considerably in the last century; and this is why medicines, once approved by the relevant agencies, tend to work reasonably well for their intended purpose. But, as scientific products, they are not absolutely good: they have contraindications and may produce undesirable effects. This is something that should be well known and is, on the other hand, easily verifiable: take the medicine at hand and look at its list of side effects and contraindications. But just because it has contraindications does not make it absolutely bad: the goodness of a medicine depends on whether it solves many more problems than it can create.
In this respect, the success of vaccines is unquestionable. Over the last century and a half, vaccines have brought about a dramatic improvement in the health of humankind. They have eradicated terrible diseases that have claimed the lives of hundreds of millions of human beings throughout history, and have prevented the deaths of hundreds of millions more from diseases that would still be killing people in droves were it not for vaccines. And they will continue to provide essential help in this current coronavirus pandemic: vaccines will be the ones to get us out of the huge health, economic and social mess that SARS-CoV-2 got us into a little over a year ago. But vaccines have some side effects and contraindications. Now, with the information we have today, a few simple calculations are enough to realise the tremendous folly of forgoing the benefit of vaccines for the sake of avoiding these minimal adverse effects.
Given over the scientific committees that advise governments on medicines (European Medicines Agency, US Food and Drug Administration, etc.), the political decisions of governments prevail, and given that vaccination is a matter of individual freedom (in almost all parts of the world) even if it ends up affecting society as a whole, citizens should be well informed so that they can evaluate both political and their own decisions on a matter as important as this vaccination, and of such transcendence for society as a whole.
For the calculations I will take the Janssen vaccine as an example. It emerged yesterday that the US FDA (and also the Centers for Disease Control and Prevention) has recommended temporarily suspending its administration. Almost the same calculations apply to the AstraZeneca vaccine, which is also being heavily questioned, although no drug agency has advised against its use.
Janssen’s vaccine (like all the others) has undergone an exhaustive study process before being authorised by the national drug agencies. On the one hand, it has had to prove that it is effective (at least under the controlled conditions of clinical testing) and that it does not produce statistically significant adverse effects. To do this, tens of thousands of tests have been carried out on volunteers, appropriately chosen to ensure that there is no statistical bias in the results. In the universe of these tens of thousands of volunteer trials, the vaccine has shown a relative efficacy of 66%, rising to 85% for preventing severe cases of Covid-19 (between the actual group of vaccinees in the trials and those who received a placebo). The vaccine has shown no statistically relevant adverse effects. This is not to say that there are no adverse effects, but that they are incomparably less than the damage that would be caused by the disease if the vaccine were not used.
Monitoring the effects of vaccines does not end with their approval. Rigorous monitoring continues as the vaccines are applied. It is then that their effectiveness in controlling disease under real-life conditions (outside the more controlled conditions of clinical trials) can be truly measured. In addition, more information will be available on what other adverse effects occur when large populations are vaccinated. Note that some adverse effects are so statistically insignificant that they may not appear in previous clinical trials (in the tens of thousands), and will only be detectable when administered to larger populations (hundreds of thousands, millions or even hundreds of millions or billions of people, as will be the case for Covid-19). This continuous review of data is an inherent part of the scientific method: one must continually check theoretical approaches against experimental fact, and make changes to the former if the experiments do not match the theory.
It was during this monitoring process that half a dozen of the seven million or so people vaccinated with Janssen in the US were found to have developed dangerous thrombi. One of those people has died and another is very seriously ill (as of this writing).
Although it has not yet been proven that there is a link between the vaccine and the thrombi, that dead person is irreplaceable, and the pain suffered by others is irreplaceable. But in statistical terms, these adverse effects are irrelevant (which does not preclude thorough investigation, which is what is being done right now and why vaccination with Janssen has been temporarily suspended in the US). One consideration before doing the simple calculations that will show why, despite these effects, it is necessary to continue to vaccinate. I have made this consideration on other occasions, but it bears repeating: it makes me a little uneasy to write about counting and estimating infected and deaths. I know that in the statistical treatment of diseases it is inevitable to compute deaths with numbers, but it is useful from time to time to remember that behind those numbers there are human beings, and that each number we now associate with a death used to count a life. No life is irrelevant, however irrelevant the statistic of one death in six million may be.
And now I come to the calculations. These are simplified estimates (which lose precision but gain clarity of exposition), so the important thing is not to look at the specific numbers but at their order of magnitude.
In Spain, 6 million people are expected to be vaccinated in the next quarter with the vaccine developed by Janssen (to put it in round numbers). Extrapolating from the episodes of thrombi that have occurred in the USA, we can expect between 5 and 6 episodes in Spain, of which 1 or 2 could end in death.
But what would happen if, in order to avoid these adverse events (terrible, no doubt, but statistically insignificant in a sample of six million people), we stopped giving the vaccine?
That would mean that it would be months before those six million people were vaccinated with another vaccine (all of which also have statistically insignificant adverse effects, let’s not forget). However, it is estimated that since the pandemic began in Spain in February-March 2020, each month has infected between 1% and 1.5% of the population on average. In other words, each month of delay in vaccinating these six million people would generate between 60,000 and 90,000 infected by the virus. Reliable estimates put the number of people who would become seriously ill enough to require hospitalisation at 5%: we can therefore conclude that by avoiding 5 or 6 episodes of thrombosis, we will have generated between 3,000 and 4,500 serious hospital admissions every month (on average; the figure will depend on the evolution of the epidemic at any given time). The situation is more serious when we look at the figures for deaths: if we take into account that 1% of those infected will die, we will have generated between 600 and 900 deaths each month (on average) by avoiding 1 or 2 deaths.
In the case of thrombi, there is also a terrible paradox. It is estimated that 25% of patients admitted to the ICU with coronavirus suffer thromboembolic episodes. Given that the six million unvaccinated people will generate between 300 and 450 admissions to the ICU per month, to avoid 5 or 6 episodes of thrombi (assuming they were caused by the vaccine), we would have between 75 and 113 episodes of thrombi each month among patients admitted to the ICU for Covid-19 (I do not count here the thrombi suffered by patients after overcoming Covid-19, statistically much more significant than those caused by the vaccine).
This is what has to be weighed in the balance: on the one hand the statistically irrelevant adverse effects supposedly to be expected from applying the Janssen vaccine to six million people (5 or 6 seriously ill due to thrombi and 1 or 2 deaths), on the other hand the effects produced by the disease by not acting against it using the vaccine (an average of between 3,000 and 4,500 people hospitalised, between 75 and 113 episodes of thrombi caused by Covid-19 in ICU patients, and between 600 and 900 deaths; this for every month that the vaccine is delayed).
Keep this in mind when you are called for vaccination.
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