Adriana santagati
Dew magnani
04/04/2021 6:00
Clarín.com
Society
Updated 04/04/2021 6:00 AM
The president's positive for coronavirus, Alberto Fernández, repeated the repeated question of whether a vaccinated person can get Covid, and also updated doubts about how the vaccinated can also infect.
From the explanations of various referents in infectology and microbiology to
Clarín
, these are the answers to 10 of those questions.
1. How many other vaccinated have been infected so far?
The Ministry of Health of the Nation reported this Saturday that 0.15% of those who received the first dose (4,212 people) were reported as positive for Covid after at least 14 days of the application, and the same percentage was confirmed positive later of the 14 days of the second dose (1003).
Roberto Debbag, vice president of the Latin American Society of Pediatric Infectology, explains that there are more people with infection in the first 14 days because they have not yet had an immune response.
For the expert, these numbers are also relative because we do not know the total numerator of people who have received the first dose at different ages.
"They are
incomplete data
, such as a few weeks after Sputnik began to be administered, the Government reported that 1% of those vaccinated with Sputnik V had had adverse effects and it was not," he explained.
2. How is it controlled if a vaccinated person is infected?
With the vaccines already being applied, we are going through
phase IV of the clinical studies
, the pharmacovigilance process in which adverse effects are reported and also the efficacy of the vaccines.
According to Debbag, this surveillance should be active and not just passive as is being done now, vaccinated people who become infected, have a confirmed diagnosis by PCR and are loaded into the SISA system.
3. Why can a vaccinated person get it?
The vaccines are administered intramuscularly and from there "awaken" the immune response in the person.
They work by tricking the immune system
into attacking the virus once it has entered the body.
But they do not prevent its entry, what they do is help it not reproduce quickly.
Therefore, according to development, they prevent infection in a high percentage, which is between 70 to 90%.
4. Why are there people in whom the vaccine manages to prevent infection and in others it does not?
First of all, it weighs how the person develops their immune response, and in this case age is an important factor:
a greater immune response develops the younger one is
.
But the probability of contagion while being vaccinated will also depend on other variables, such as the number of immunized people in the community.
“As much as the herd effect has to be from 70%, the more vaccinated people there are, there is less probability of circulation.
In this period in which we do not have access to the vaccine, there is not a significant percentage of people who are vaccinated.
So, of those who are vaccinated, when faced with a situation of high circulation,
a small percentage can become infected
”, explains Debbag.
5. Do vaccines protect 100% against severe forms?
100% protection does not exist, but there is a high efficiency that is close to that number in preventing serious diseases.
“But that is in healthy general populations - warns Debbag - We do not know if a person who has a previous hematological, heart or lung disease if this occurs in 100%.
Possibly in these people
the probability of severe disease is highly reduced
, but the exact number is not known ”.
“Most of those vaccinated are not going to have serious illnesses.
They are going to be hospitalized, but they are not going to die
”, contributes Pablo Bonvehí, scientific director of Fundación Vacunar and member of the Committee of Experts that advises Alberto Fernández.
6. Sputnik is 91.6% effective overall in two doses.
Does that mean there is an 8.4% chance of getting the vaccine?
Infectologists dismiss this calculation out of hand.
"The medical sense is much more complex," clarifies Angela Gentile, head of the Epidemiology department of the Gutiérrez Hospital and a member of the National Commission for Vaccine Safety (Conaseva).
To measure the efficacy of a vaccine, a study is carried out in which one group is vaccinated and the other is given a placebo, and when a number of infections determined according to the sample size is reached, the numbers of cases are compared .
For Sputnik V, for example, there were 16 cases of Covid-19 in the vaccine group of 14,964 participants (0.1% of those vaccinated) and 62 in the placebo group of 4,902 participants (13%).
“But in addition, other
outcomes
or cut-off points
are extracted -
points out the pediatric infectologist -, which measure the efficacy for severe disease, for hospitalization in therapy or for mortality.
It is proven that these vaccines protect against serious forms, but not against the risk of suffering Covid, which means that Alberto Fernández can perfectly suffer from a mild or moderate condition, but he
has very good protection for everything that is serious
. "
7. Can the vaccinated still spread the disease?
As stated, vaccines do not prevent the virus from entering.
"Basically, vaccines are effective to prevent infection in some cases and, in others, to prevent serious forms, complications and reduce mortality from Covid," explains infectologist Florencia Cahn, president of the Argentine Society of Vaccination and Epidemiology (SAVE), and also a member of the advisory committee.
"It is more likely that (the vaccinated person) has mild or asymptomatic forms, but it can be infected and infect others," he added and warned that vaccinated people should continue with "absolutely all care", such as the use of the chinstrap, the distancing and ventilation: "They can have the virus and can transmit it to others, even without having symptoms."
8. Is there a vaccine that can prevent a vaccinated person from spreading it?
"There are some studies that are showing that in some vaccines, such as Pfizer's, a vaccinated person who is asymptomatically infected with Covid
may not infect,
" says Bonvehí.
However, he points out that it is necessary to be "cautious" because there is a lack of data to corroborate these first studies.
In fact, the Centers for Disease Control and Prevention (CDC) in the United States rectified comments made by its director, Rochelle Walensky, who had suggested that people who are vaccinated against the coronavirus do not transmit the virus to other people.
In addition, it is not possible to know who will make up the percentage of vaccinated who will be infected with symptoms.
9. Do the vaccinated transmit the virus in a milder way than those who have not been vaccinated?
The viral load that a person can transmit is apparently related to the
clinical form in which the
coronavirus
disease occurs
, says Gentile.
“A vaccinated person who makes an infection spreads to others.
What happens is that it is a manageable, moderate or mild clinical form, with which it may also be that their viral load is lower ”.
However, he points out that there are also unvaccinated people who have mild forms of the disease.
For example, an unvaccinated young adult with mild symptoms may have
a viral load similar to an infected vaccinate with mild symptoms
.
“For this reason, the greatest benefit that these vaccines give - Gentile continues - is to prevent the risk of hospitalization, entry to therapy and mortality.
That is why the urgency of vaccinating the vulnerable population first ”.
10. Efficacy and effectiveness are not the same.
How are these concepts applied today?
While efficacy arises from controlled work that laboratories do and then present to regulatory authorities, such as ANMAT, for vaccines to be approved, effectiveness is real-world evidence, that is, how much they protect outside of trials those vaccines.
"This is always measured through the epidemiology areas of the institutions," Gentile explains and exemplifies that if a doctor tests positive for Covid and has already received both doses of the vaccine, they report to ANLIS-Malbrán for the institute to make a genomic sequencing and rule out that it is not a new variant that responds less to the vaccine.
In Argentina, four variants of Covid-19 have already been identified: those detected for the first time in the United Kingdom, Manaus, Rio de Janeiro and California, but not the one that originated in South Africa.
ACE
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