What about long term side effects?

“Would you like to receive the coronavirus vaccine as soon as it arrives?” The question is on the menu of the day in any conference in Argentina. Some of those who respond that they prefer to wait a bit claim that “We don’t know what effect they can have in the long term” vaccines against covid19. However, from what he was able to find Bugle By interviewing experts and looking at historical data, while it’s true that new vaccines leave some room for uncertainty, a lot is known about possible long-term adverse effects of vaccines.

Among the vaccines for various diseases approved by regulatory bodies, late adverse events, that is, those that might appear some time after the start of mass vaccine application, They are rare. And if they do appear, they usually affect a very small number of the vaccinated population.

For Daniela Hozbor, a doctor of biochemistry who works at the Institute of Biotechnology and Molecular Biology (Conicet, University of La Plata), it is understandable that questions arise about what the covid-19 vaccine might do in the organism in the medium or long term. Because we are faced with vaccine approvals as part of a health emergency, which involves shorter deadlines.

However, she points out that at each of the stages that vaccines go through in their development (from phase 1 to 3), the number of individuals in which they are tested increases, and at each stage the safety of the compounds is analyzed. . In phase 3, in particular vaccines are tested in a very diverse population. “I think this is the most important thing when evaluating potential side effects,” says Hozbor.

The expert explains that in vaccine trials, the first checks on possible adverse effects are carried out immediately after immunization and up to 72 hours after the second immunization. However, people who participate in the trials are going on with their normal lives and could experience an adverse reaction, due to an unexpected combination of factors. This, on the whole, has not been seen with the COVID-19 vaccine candidates, Hozbor says. And adds that, anyway, vaccine surveillance continues when they were already introduced into the “real population”. This is where the immunizing substance comes into contact with all human diversity in terms of ethnicity, environmental factors and possible pathologies.

When asked quickly about the possibility of late onset side effects, Hozbor said: “Rarely do they appear.”

To graphically represent what we are talking about when we talk about the rarity of side effects, Hozbor uses what is happening with existing and long used vaccines. Some of them present risks of serious side effects in proportions which, depending on the vaccine, range from 0.2 to 4 cases per million vaccinated.

In the same vein, Daniel Stecher, head of the infectology department at Clínicas hospital, dependent on the UBA, previously said Bugle that with certain vaccines, when used on a massive scale, certain events have been observed which had not been detected in previous studies. But in general, these are specific cases, which did not affect the vaccination program and that they did not occur with a significant frequency, so that they could be detected and controlled.

Stecher opens the spotlight and places COVID-19 vaccines in a larger context. Any drug, any drug, any vaccine will have an adverse effect, he says. “It is even said that a drug that has no adverse effects is likely to also do not have beneficial effectsHe says. And it goes on: What comes up about vaccines can be questioned about all the vaccines we use so far. Vaccines have a ‘very very low’ level of adverse events, serious and when we weighs them against the ability of vaccines to prevent disease and save lives, [se tiene que a] vaccines you have to use them“, continues Stecher.

Kathryn Stephenson is the Director of the Clinical Trials Unit at the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, and works on trials of several COVID-19 vaccines. When asked how he would reassure people who are asked to be vaccinated, Stephenson said, quoted by the US network CBS: “The first thing I would say is that it is very unusual for a vaccine to have a long-term side effect. Most of the side effects associated with vaccines are related to the onset. Something like an allergic reaction. And this is true for all vaccines. “

Hozbor raises another issue for consideration: several of the formulations used in the development of coronavirus vaccines have been used in other vaccines, and they have not shown any indication that they may generate a particular adverse reaction.

Among the possible side effects of anticovid-19 vaccines, an article in the British BBC channel mentions “the potentiation of antibody-dependent infection” (ADE, its acronym in English). It is a reaction in which, upon contracting the infection, the vaccinated person suffers from an increase in symptoms. The mechanisms of ADE, which are very rare, are poorly understood. Hozbor says that since the start of the pandemic, this question has circulated in scientific fields and is kept in mind in trials. However for now there is no known evidence that covid-19 vaccines cause RDW.

An article published by the California Health Care Foundation (CHCF), an organization that works for equitable access to health, recalls that in 1976, a mass vaccination program against swine flu was stopped when cases of Guillain-Barré syndrome (GBS, its acronym in English ) have started to be detected. ) in vaccinated people. At the time, the text notes, no one knew how common GBS was, so it was unclear whether or not the episodes were related to the vaccine. “Ultimately, the scientists found that the vaccine increased the risk of the disease by one more case per 100,000 vaccinated patients,” the CHCF note said.

And the text continues: “A typical seasonal influenza vaccination increases the risk of contracting GBS by about one more case per million people. It is very, very difficult to determine whether a rare event was caused by a vaccine, said William Schaffner, infectious disease specialist at Vanderbilt University School of Medicine: “ How do you attribute an increased risk of something that happens in a person in a million? ‘”.

LGP