It was a routine checkup.
The doctor told the man that he better wait and get
vaccinated against Covid
in Europe, his vacation destination, because “the one they give is better.”
Indeed, the main laboratories are launching new doses against the coronavirus, not bivalent but now monovalent,
the monovalent XBB
.
The reason for the swerve?
A scientific challenge called
immunological imprinting
.
It should be noted that all those consulted for this note rejected the suggestion of the doctor cited above.
Jorge Geffner, renowned immunologist and Senior Conicet researcher at the Institute for Biomedical Research in Retroviruses and AIDS (INBIRS), pointed out that, “considering that airplanes are a possible source of contagion, the advice is that if the person gets a reinforcement,
get vaccinated before traveling
, whether the bivalent or the Covid vaccine that is available.”
The medical representatives of the two main vaccine laboratories against SARS-CoV-2 underlined the same.
Julia Spinardi, Medical and Scientific Affairs leader of Pfizer's Emerging Markets Covid Unit, emphasized that, “to have protection against serious illness, it is
never a good idea to wait
.”
And according to Paula Pertzov, medical manager at Raffo, the Moderna license laboratory in Argentina,
“waiting is not being vaccinated
. ”
The world is running behind the capricious changes of the pandemic virus.
The circle is vicious: hanging with reinforcements results in more hospitalizations.
Hospitalizations, with greater chances of the virus mutating and generating genomic changes that escape the immune response generated by vaccines, given that hospitalized patients with severe Covid are like large reservoirs or viral multiplication plants.
Although the recommendation is to respect the recommended vaccination schedule, it is true that the new immunological tools that are emerging in the northern hemisphere
arrive in these pampas with a delay of a few months
.
Thus, even though the bivalent ones protect against serious illness and even though in this wave of infections many feel they are “at the forefront” by receiving these enhanced doses, from the point of view of scientific-technological evolution,
the bivalent one, in reality , it was
already
A new monovalent vaccine against Covid
Compared to times in the northern hemisphere, the doses adapted to the changes of the SARS-CoV-2 virus arrive later in Argentina for two reasons.
The first is that, “being American,
it is necessary for the vaccine to be approved in the local market
, before requesting authorization from other regulatory agencies,” Spinardi explained from Pfizer.
Reinforcements in vaccination against Covid.
Photo EFE/Manuel Bruque
The other reason is that, in practice, the drug regulatory agencies of the United States and Europe (FDA and EMA, respectively) function as
“beacons” for their global peers
.
In the case of Argentina, from the ANMAT.
In other words, a medicine that comes with the green light from these organizations (whose reputation is, in several senses - although not all -, "unquestionable"), although it will pass through the demanding local sieve, will initially have several beans to favor.
It is worth remembering that, symbolically, the lack of these beans
was part of the questioning of the Russian Sputnik V vaccine
.
Pertzov, Moderna's medical representative, explained that modifying the vaccine to adapt it to the current circulating virus takes about 90 days: “As with the flu, the FDA looks at the new circulating strains and asks the laboratories to update the vaccines.
From now on, we will always be behind the virus, which
mutates permanently
.”
Spinardi agreed and explained that, in this case, “the process of adaptation to the Covid XBB variant was indicated by the World Health Organization and by the FDA and EMA.
Once it is determined which variant to target, the messenger RNA platform
allows the vaccine to be modified very quickly
, in about 100 days.
After that period, it will be completely ready from a production point of view.”
Both, Pfizer's monovalent XBB and Moderna's,
are today being reviewed by ANMAT
, an organization respected in the world but which, as is known, takes its time.
However, the representatives estimated that, if everything goes smoothly (ANMAT approves and the Argentine Health authorities recommend it),
the monovalent XBB should be available to people no later than winter
.
Even before.
Is this a reason not to get vaccinated now and wait for it?
Definitely not.
To understand this, it is worth explaining why laboratories are returning to
monovalent vaccines
.
Covid vaccines: from bivalent to monovalent XBB
The bivalent ones had been proposed as
surpassing the first generation of vaccines
, given that they were directed against two targets, and not just one.
The targets that were then proposed were, 1) to combat what everyone calls the “original variant”, or informally, “Wuhan”, and 2) to also focus on the genomic version of Covid that was widely considered “the” variant. which guaranteed the virus great contagiousness and less virulence.
We must not forget that to continue multiplying, SARS-CoV-2 needs us alive...
We are talking about
Omicron, with its thousand and one facets
(daughters and granddaughters of that variant) full of numbers and letters that are impossible to remember.
From XBB to JN.1, to name just a couple.
Vaccination against Covid at the beginning of 2023 in Avellaneda, province of Buenos Aires.
Photo Maxi Failla
However, now the laboratories decided to design a proposal that, they say again,
is superior
: monovalent vaccines (like the ones we used before the bivalent ones), but with the novelty that they do not target Wuhan but
only against Ómicron
.
The explanation for this change lies in the concept mentioned at the beginning of these lines: the so-called
immunological
imprinting
.
Covid, vaccines and immunological imprinting
In English, “
imprint
” means “to print,” but also “to leave a mark.”
“
Imprinting
”, in turn, means “imprint”, so that immunological
imprinting
means the persistence of a printed imprint that
directs immunity in a certain direction
.
This is how Geffner explained it: “In one way or another, whether through infection or vaccines, almost everyone came into contact with the original Wuhan variant.
What generates the phenomenon of
immunological
imprinting ?
That, even when you are vaccinated with a dose based on one derived from Ómicron, you continue to 'remember' the original variant.
The thing is that, even if the variant is another, it will share reasons with Wuhan because
both are, ultimately, SARS-CoV-2
.”
In orange, particles of the virus that causes Covid disease.
Photo NIAID/National Institutes of Health via AP
“We say that they share epitopes, in reality,” explained Geffner, alluding to the technicality by which certain portions of a molecule manage to be recognized by immunological memory.
The problem generated by
imprinting
is that if the immune system dominantly recognizes Wuhan, the protection with vaccine boosters will be reinforced in that direction, even when the vaccine contains a second target (in the case of the bivalent vaccines, Ómicron). .
So?
The laboratories decided to
remove the reference of the original variant from the new doses
to improve the bias of immunological
imprinting
.
Geffner believes it is a good plan, but stressed that, to date, there are no published studies that
demonstrate the superior effectiveness of these vaccines
(compared to previous ones) in avoiding hospitalizations.
“Everyone tries to twist immunological
imprinting
.
And not only in Covid.
This is a big problem also in influenza.
That is why flu vaccines have
an effectiveness that does not exceed 40% or 45%
”, He explained.
The laboratories point out that the new monovalents awaken
a higher antibody titer
, but Geffner clarified that "there is absolutely no published study that demonstrates that the new monovalents are superior in preventing severe infection."
Because, “even when different levels of neutralizing antibodies are seen, that does not imply greater immunogenicity, in addition to the fact that they are very subtle differences.”
“We always think of antibodies as the conclusive data, but protection for severe infection is not measured by antibodies as much as by the T lymphocyte response,” explained the scientist, and closed: “In this sense, the levels of effectiveness between some vaccines are not that different.
The indication continues to be to get vaccinated according to the recommended schedule with the doses that are available where one is.”