The four tactics of vaccines to train the immune system
22 June, 2020
Epidemiologist Martín Moreno: "It is indisputable that Spain arrived late"
22 June, 2020
Having a vaccine to prevent covid-19 will be the turning point in controlling the pandemic. More than a hundred projects design the key to herd immunity.
When they work, vaccines don't make news. Because, without making noise, they protect. Some of the diseases they prevent have almost disappeared and we do not perceive any risk around. That makes them almost invisible. Why get the polio vaccine if there is no polio?
"Except for water purification, no other health action has saved and continues to save more lives than vaccines," says Wenceslao Varona López, a doctor specializing in Preventive Medicine and Public Health at the Royo Villanova Hospital in Zaragoza. And he puts figures to his statement: "Vaccination against diphtheria, tetanus, whooping cough and measles saves two to three million lives every year and many more from suffering from these diseases; it is estimated that if these vaccines reached "All those who would benefit from receiving them, the people saved each year would be one and a half million more; in total, 3,5-4,5 million lives, equivalent to those of the inhabitants of Madrid."
"Imagine not having had vaccines against polio, measles, rubella, meningitis..., we simply could not live in society!"
But in recent months, we have rediscovered what it means to not have a vaccine. Covid-19 is very visible. Without prevention against an unknown virus, we have had to paralyze the world to stop its advance. Carlos Martín, head of the Mycobacteria Genetics group at the University of Zaragoza, highlights that "we are witnessing the effects of not having an effective vaccine against a single infectious disease, caused by a virus, SARS-CoV-2, and "The economic and social impact is being devastating. Imagine not having had vaccines against polio, measles, rubella, meningitis..., we simply would not be able to live in society!"
Although it is still early to understand the specific immunological mechanisms that Covid-19 triggers, "it does not seem that the pandemic is going to disappear on its own," predicts Jesús Gonzalo, a researcher from this same group, so a preventive strategy, such as vaccination , would contribute enormously to the protection of the population, especially those most vulnerable." And it would be the key to something more similar to the longed-for old normality.
Data from the seroprevalence study indicate that approximately 5% of Spaniards have developed antibodies against SARS-CoV-2, but the real herd immunity could be higher. The reason is that, in addition to the antibodies that these tests measure, "there are other components of the immune system that are important in the control of covid-19," says Gonzalo. For example, adds Martín, "cross-cellular immunity against other coronaviruses could play a certain role in group immunity," that is, colds caused by other coronaviruses could generate protection.
Herd immunity is precisely what vaccines provide, a public therapy that helps an entire population, not just an individual, stay healthy. And that is what we are missing today.
Race against time
That is why the covid-19 vaccine is news. Because we don't have it yet and the race to get it as soon as possible brings together government agencies, pharmaceutical and biotechnology companies and even independent organizations all over the world, embarking on numerous research projects.
"There will surely be more than one candidate who arrives first, which does not mean that he is the best," says Jesús Gonzalo. "The vaccines in the current vaccination schedule have a long clinical history, which has allowed us to know them very well, adjust their dose, avoid interference with other vaccines or select the best age group for vaccination. Due to the urgency, this is not "if possible with the vaccine against covid-19". There is a wide range of vaccines in experimentation and "it is possible that some of them require several doses, while with others one immunization is sufficient."
In the opinion of Carlos Martín, "the first to be vaccinated should be personnel considered at risk, such as healthcare personnel and nursing home workers, and the most susceptible people, such as those over 60 years of age."
"In the face of infectious diseases, solidarity is essential. If I do not protect myself, I also fail to protect those who come into contact with me. And that is not fair"
But not everyone would be first in line to receive the vaccine. Some researchers warn of reluctance on the part of the population, led by anti-vaccines. For Varona, "in the face of infectious diseases, solidarity is essential. If I do not protect myself, I also fail to protect those who come into contact with me. And that is not fair." The eternal debate arises about how far individual rights go.
Gonzalo adds that "unfortunately, Covid-19 affects older people, surely if it affected babies and infants, there would be fewer objections to the search for a vaccine against SARS-CoV-2."
"The absence of immunity against a new disease is the best example of what can happen when there are no vaccines," he adds. "Evidently, vaccines contribute to conferring group immunity that will indirectly protect individuals who have not been vaccinated. "If the percentage of unvaccinated individuals is high, herd immunity does not occur and outbreaks of the disease may occur, making it difficult to control. This is what is happening, for example, with measles." According to the WHO, reluctance to prevent has caused cases to increase by 30% in the world.
For those who distrust the safety of a quickly developed vaccine, Nacho Aguiló, coordinator of the immunity team of the new Unizar tuberculosis vaccine (MTBVAC), clarifies that "no matter how much we are in a hurry to find a vaccine for covid- 19, safety remains paramount. Let us consider that if we aim to ideally vaccinate the entire population worldwide, there are almost 8.000 billion people. If there were a serious problem, for example in one in every 10.000 individuals, this would mean. "many millions of people affected, which would probably be unaffordable even if the remaining 9.999 were protected." Likewise, remember that it is not the companies that develop clinical trials that decide whether or not a vaccine reaches the population, but rather it is the governments of each country, through their respective drug agencies, that decide, based on safety and efficacy data." In the particular case of vaccines "they tend to be extremely cautious, due to the fact that they are administered to a healthy population."
