Leo González Pérez
12/18/2020 6:00 AM
Clarín.com
Society
Updated 12/18/2020 9:42 AM
"Would you get the coronavirus vaccine as soon as it arrives?"
The question is on the menu of the day in any talk in Argentina.
Some of those who responded that they would prefer to wait a while argue that
"it is not known what effect they may have in the long term
.
"
However, from what
Clarín was
able to find out by
asking experts and reviewing historical data, although it is true that the new vaccines leave some room for uncertainty, a lot is known about the possible long-term adverse effects of vaccines.
Among the vaccines for different diseases approved by the regulatory bodies, late-onset adverse events, that is, those that could appear some time after the vaccine began to be applied in bulk,
are rare
.
And if they do appear, they usually affect a really very small number of the vaccinated population.
For Daniela Hozbor, a doctor in 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 vaccine against covid-19 could do in the body in the medium or long term term.
Because we are facing approvals of vaccines in the context of a health emergency, which implies
shorter deadlines
.
However, she highlights that in 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 grows, and at each stage the safety of the compounds is analyzed .
In phase 3, especially, vaccines
are tested in a very diverse population
.
"I think that's the most important thing when evaluating potential adverse reactions," says Hozbor.
The expert explains that in vaccine trials the first controls on possible adverse effects are carried out immediately after immunization and up to 72 hours after the second dose.
However, the individuals who participate in the trials continue with their normal lives, and in it they could face an adverse reaction, due to an unexpected combination of factors.
That, in general, was not seen with the candidates for vaccines against COVID-19, says Hozbor.
And he adds that, anyway,
surveillance on vaccines continues
when they have already been introduced into the "real population."
It is there where the immunizing substance comes into contact with all human diversity in terms of ethnicity, environmental factors and possible pathologies.
The vaccine candidate from the University of Oxford and AstraZeneca and the Russian vaccine Sputnik V. Photo AFP.
When asked promptly about the possibility of late-onset adverse effects, Hozbor says:
"They are rare."
To graph what is being talked about when it comes to the rarity of adverse effects, Hozbor uses what happens with vaccines that already exist and have been in use for a long time.
Some of them present risks of serious adverse effects in proportions that, depending on the vaccine, go from
0.2 to 4 cases per million vaccinated
.
In the same sense, Daniel Stecher, head of Infectology at the Hospital de Clínicas, dependent on the UBA, told
Clarín
that with some vaccines, when used in a massive way, some events have been observed that had not been detected in previous studies.
But in general these are specific cases, which
have not affected the vaccination program
and which have not occurred in a significant frequency, so that they could be detected and controlled.
Stecher opens the spotlight and puts COVID-19 vaccines in a broader context.
Any drug, any drug, any vaccine is going to have an adverse event, he points out.
"It is even said that a drug that does not have adverse events is likely to
have no beneficial effects either
," he says.
And it continues: what is being raised in relation to vaccines can be asked about all the vaccines we use so far.
Vaccines have a "very very low" level of adverse events.
"There are very few severe adverse events, and when you balance them against the ability of vaccines to prevent disease and save lives, [you have to]
use
vaccines
," summarizes Stecher.
Kathryn Stephenson is director of the Clinical Trials Unit at the Virology and Vaccine Research Center at Beth Israel Deaconess Medical Center in Boston, and is working on trials of several COVID-19 vaccines.
When asked how he would reassure people who are asked to get vaccinated, Stephenson said, as quoted by 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 have to do with the beginning. Something like an allergic reaction. And that's true for all vaccines. "
Facilities of the Catalan pharmaceutical company Reig Jofre, which agreed with Janssen Pharmaceutical to produce its vaccine against the coronavirus.
Photo EFE.
Hozbor raises another issue to take into account: several of the formulations that are being used in the development of vaccines against the coronavirus
have already been used in other vaccines
, and they have not presented indications that they could generate an adverse reaction in particular.
Among the possible adverse effects of the anticovid-19 vaccines, an article from the British channel BBC 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 increased symptoms.
The mechanisms of ADE, which is very rare, are poorly understood.
Hozbor says that since the pandemic began, this issue has circulated in scientific fields and that it 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 massive vaccination program against swine flu was stopped when cases of Guillain syndrome began to be detected -Barré (GBS, its acronym in English) in people who had been vaccinated.
At the time, the text notes, no one knew how common GBS was, so it was difficult to know whether or not the episodes were related to the vaccine.
"Ultimately, scientists found that the vaccine increased the risk of the disorder by one additional case per 100,000 vaccinated patients," says the CHCF note.
And the text continues: "The typical vaccination against seasonal influenza increases the risk of contracting GBS by about
one additional case per million people
. It is very, very difficult to determine if 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 occurs to one person in a million?'
LGP
Look also
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