The vaccination campaign against covid-19 has been possible thanks to a gigantic scientific effort to develop several vaccines in record time, which must now continue with the global distribution and application of hundreds of millions of doses. However, it has also raised doubts in some people, who seem to be concerned that they may not have all the possible guarantees. They argue that this requires tests of safety and protective efficiency extended in several stages, over much longer periods of time.
The benefit, in terms of global health, of the wide application of vaccines is unquestionable. This, despite the reluctance of small population groups encouraged by messages with a dubious scientific basis that circulate on the internet. Those considered safest (influenza, triple virus) have an incidence of serious adverse effects of 1 or 2 cases per million inhabitants and this does not invalidate their protective character, widely demonstrated. It is true that they have been tested in real populations for decades.
In contrast, the new covid-19 vaccines have only had a chance to be tested in the thousands of people who have participated in clinical trials, in controlled settings. These are essential to draw conclusions about the validity of any treatment that is tried, and that they are not masked in the inevitable casuistic heterogeneity of the real world. It is the lack of its massive application, in the millions of individuals who represent much better the real structure of the population, which makes inevitable a certain uncertainty that can only be cleared after years of application and analysis.
The question is what is the balance between risk and benefit that can be considered acceptable under the current circumstances.
In medicine, the approach to start applying new treatments is based on approval by regulatory agencies. These should ensure that all studies and trials to assess safety and efficacy have been properly conducted. Once the treatment in question is approved and available in the clinical arsenal, doctors carefully assess this balance between risks and benefits with the maximum guarantee of “first of all, do no harm.”
However, in the current scenario, the elements of analysis are not complete if essential public health criteria are not invoked as well.
A global analysis for a global problem
When the probability of adverse effects in an individual is evaluated, the incidence on each of the people who follow a treatment, the balance between the risk of the procedure that is applied and the benefit that is intended to be avoided, is evaluated. In the case of the impact of covid-19, this also means taking into account the impact of not preventing the infection of the general population, represented in each of the individuals who are not vaccinated.
Each person who does not get vaccinated, even if their risk of contracting COVID-19 is low, puts the rest at risk. Not only the most vulnerable sector of the population (which could be protected if these people are vaccinated), but the entire population. This includes people who do not even know how vulnerable they are because we do not yet know many of the factors that make such huge differences in susceptibility to the most severe version of the disease.
The fundamental difference between covid-19 and other diseases also caused by infectious agents is that we do not yet have basal defenses against a new virus. The result is being seen: an unbridled spread of the infection to the entire world population, which adds additional risks that increase with each day that we go without vaccination.
The probability that variations and mutations will appear in strains that could escape the immunity provided by vaccines is increasing. It is the law of large numbers, as microbiologists well know. In addition, the viral loads and the population incidence of the SARS-CoV-2 virus currently have nothing to do with that of the agents that cause influenza or other diseases with which we have been living for a long time.
Our world, moreover, is today completely interconnected on a universal scale. This allows it to be extended, in a short period of time, to any viral variant that escapes natural or vaccination-induced immunity. This is fundamentally the responsibility of epidemiology and public health, and it is very important to explain well the arguments along these lines so that people value population arguments, not just personal medicine.
Understandably, people prioritize their personal risk / benefit over collective benefit. For this reason, it is crucial to reinforce this collective aspect in communicating the importance of vaccines.
A single health
Another argument in favor of mass vaccination comes from biology. In a recently published work it has been determined that there are more than 1 000 species of coronavirus similar to SARS-CoV-2 in bats. Each of them is susceptible to unleashing another pandemic if it crosses the threshold between species and certain conditions are met.
If we swap bats for other species, much less is known about coronaviruses or other viruses that could use them as hosts. For example, the pet population is comparable to human in size, but it is not studied at the same level because its interest is secondary compared to human health. With a human population that supports such a massive number of viruses as the current one, the probability that any of these viruses from animals will recombine with SARS-CoV-2 and end up generating a new species or strain is increased.
This would be well explained by geneticists and microbial ecologists. Hence the idea of One Health, which this health crisis is bringing to the table more than ever. Human, animal and environmental health are the same thing.
This is the fundamental reason why it is urgent to act to reduce the spread of SARS-CoV-2 infection throughout the world, also in those countries without means. This may be even more urgent than vaccination in our developed countries, well protected by enviable basic sanitary conditions. Where might these cross-species appear most likely? You can imagine if you think about the images that have been seen coming from those markets in which people and animals coexist without interruption.
The evaluations must, therefore, also incorporate sociological and political factors. Nor would it be amiss to listen to philosophers and their approach to issues that must be taken into account, related to ethics and morals when prioritizing political actions relevant to the field in question.
There is also a much more public defense of the value of the guarantee provided by drug regulatory agencies. The urgency and shortening of deadlines in the development of vaccines have not been applied at the cost of skipping the protocols that we have endowed for the development of safe drugs. The directives emanating from these agencies are safe (it is better for us) from purely economic spurious interests.
Clearing the uncertainty
There is a certain level of uncertainty that will only be cleared as the vaccination process progresses, as has happened with all vaccines from their creation to their consolidation. But the procedures that have now made it possible to develop vaccines in record time are more powerful, efficient and safe than ever. Especially in contexts like the current one, in which an unprecedented resource effort has been applied.
Today’s science and research has nothing to do with what there was twenty years ago. Penicillin would not have been approved in its day if the strict protocols that today define whether a drug or treatment is safe or not had been applied. We are talking about acting on a global scale with the maximum security that current conditions can allow. The urgency of stopping the progress of the pandemic, its consequences and cost in lives demands it.
When opinion polls reveal the enormous doubts of the population, it is crucial that our media become fully involved in explaining the collective and epidemiological concept that is at stake in vaccination against the coronavirus. It is not about simply offering a flood of information to people, so that the indigestion of not being able to assimilate it makes them refractory to everything that is not what it is convenient for them to believe, in a blind denial of the magnitude of the problem.
Jesús Pérez Gil, University Professor, Department of Biochemistry and Molecular Biology, Faculty of Biological Sciences, Complutense University of Madrid, Complutense University of Madrid
This article was originally published on The Conversation. Read the original.
