They identify the missing variable to determine when the body is protected from Covid

If we start this note by informing that researchers linked to the Oxford-AstraZeneca vaccine have confirmed that the greater the presence of neutralizing antibodies in the body, the body is more likely to escape the coronavirus symptomatic, several indignant readers will say “But wasn’t it obvious?” Not really.

Although the efficacy of a drug is tested in a series of clinical trials (the preclinical phase; then phases 1, 2 and 3, until pharmacovigilance or phase 4 is reached), as and when as knowledge of a certain pathogen progresses, it becomes clearer to scientists what bookmarks (O biomarkers) indicate that the body is able to fight this agent.

It’s hard to believe, but this data did not exist during all these pandemic months.

Everyone knows (because they say so, and they say it because it is suspected) that antibodies play an important role in the fight against SARS-CoV-2. In addition, vaccines generate antibodies, as does the post-infection recovery stage.

And we know that there is a dual dimension of immunity: cellular (or immunological) and humoral memory, carried by different types of antibodies.

Now, How much of each thing does it take to avoid falling in hospital if you contract the Covid? We do not know, at least, not with the level of precision that we have for diseases such as influenza or hepatitis B.

In fact, it is common to hear from different infectologists and biochemists what two experts told this columnist on Thursday. The discussion revolved around some facts about the vaccine Sputnik V published in the latest Country Project report.

The report concluded that “sera from individuals recovering from or vaccinated with Sputnik V showed a decrease in the titers of neutralizing antibodies by at least three times, compared to the Gamma variant”(Ex Manaus), which represents 41% of Covid cases in Argentina.

Is “three times less” a lot or a little?

So many Ricardo Rüttimann, infectologist from Funcei and member of CoNaIn, as Gabriela Turkish, doctor of biology (UBA) dedicated to virology, researcher at INBIRS-Conicet and one of the signatories of this work of the Country Project, referred to the Difficulty translating this data into real life.

In other words, it is one thing that the antibodies neutralize three times less Gamma (compared to the more “classic” variants) and it is another to predict that, thereforeThis or that could happen to patients.

Turk, however, said the decrease should not be negative: “These antibodies can neutralize the virus. It’s not that it doesn’t protect you against Gamma, it’s not that they’ve been canceled or given zero ”.

The researcher stressed that, to understand how all of this would manifest in the population, “efficacy studies must be carried out in the fields of epidemiology”.

In other words, both Rüttimann and Turk claimed that “A correlate is missing”.

Here the work mentioned above becomes relevant, a preprint (which they hope to publish in the magazine Nature) in which experts from Oxford-AstraZenca ensure that neutralizing antibodies and certain so-called “binders” are the highly sought after biomarker.

AstraZeneca

The more vaccines there are in the world, the fewer people left able to participate in double-blind clinical trials, a problem for laboratories that bet on renewing their formulas to adapt to viral mutations.

For this reason, the work (“Correlates of protection against symptomatic and asymptomatic SARS-CoV-2 infection“) Indicates that” the data obtained are useful for extrapolating efficacy estimates for new vaccines when large-scale efficacy trials cannot be performed”.

The main conclusion they came to after studying 2,000 participants from the UK is that simple, higher titers of neutralizing antibodies in the body, less likely to manifest symptomatic Covid.

They opposed two groups: some received the Covid vaccine; the rest, a meningitis vaccine. In turn, some were infected and others were not.

But, instead of just counting them to derive efficacy data, they looked at qualitatively what was happening to them: how was the display of antibody titers and its relationship to symptomatic Covid, understood to involve the lower respiratory tract.

When it is common to know people infected with Covid after they have been vaccinated, it is important to note that no vaccine can say that “yes or yes” will generate such a level of antibodies, will offer efficacy. 60% or 90%. .

In this sense, the document specifies that “protection against symptomatic Covid-19 is not absolute with any vaccine, and the results presented show that there is no single threshold value for none of the trials studied which does not indicate sterilizing immunity ”.

In addition, although “the likelihood of infection decreases on average with higher immune responses, there is a significant variation between individuals”.

But all is not relative: the heart of the work is precisely the assertion that, once the body has developed high antibody titers (the article only gives quantitative guidance), the body will have, with certainty, more chances of bypass complicated Covid images.

Pfizer and Moderna

Another important article published this week (in the prestigious The New England Journal of Medicine) complements the above. Focus on vaccines Pfizer Yes Modern, the work is called “Prevention and mitigation of Covid-19 with BNT162b2 and mRNA-1273 vaccines”.

They followed 4000 health workers and they saw if they had Covid. And in case they were infected, they assessed, once again qualitatively, what happened to them.

The results were promising: the virus was detected in 204 participants (5%): 5 were fully vaccinated, 11 had a dose, and 156 had had none.

Discovery? Among the infected, the the average viral RNA load was 40% lower in those who had received one or two doses.

“In addition, the the risk of febrile symptoms was reduced by 58% and the duration of the illness was shorter, with 2.3 less sick days in bed, ”says the newspaper, whose intention is to understand (now outside the laboratory) the interaction of Covid and vaccines in the real world.

PS