What does “puncture vaccines” mean? And what do we know about Omicron? – time.news

by time news
from Silvia Turin

Everything revolves around the term “efficacy” of vaccines: a term that can be used with at least two very different meanings: we need explanations, contextualization (and, in the case of Omicron, still patience: of course, we know very little)

While it turns out that the Omicron variant has reached all inhabited continents (with the news of the first cases in Brazil, Australia and Japan), statements about its dangerousness and its impact on vaccines used.

The statement (reported Tuesday 30 November from Financial Times) of the CEO of Moderna, Stephane Bancel, who predicted a “substantial decline” in the efficacy of current vaccines against the Omicron variant. “I think in no way effectiveness may be the same as we had with the Delta. I don’t know how long because we have to wait for the data. But all the scientists I’ve talked to say it’s not going to be good, ”Bancel said.

From many sides, consequences deriving from the possibility or not of Omicron to “puncture vaccines”. This expression, widely used (also for the sake of brevity) in media headlines, is considered equivalent to “Weaken the effectiveness of vaccines”: an expression which however needs to be specified.

LIndeed, vaccine efficacy is measured on two levels distinct:
– how much they protect people from severe cases (and therefore hospitalizations) and deaths;
– how much they protect from the contagion.

Not all vaccines protect against infection, because they act on different parts of the virus and on different mechanisms of our immune system.
All preparations against Covid, in particular, they were designed to save lives: for this reason they have so far been very “effective” (also against the variants previously reported) in the data on the reduction of hospitalizations and deaths.

We then learned that thethe effectiveness of the same vaccines against coronavirus with respect to transmissibility, on the other hand, decays over time (at least after two doses). From three months onwards, but above all after six months, “Vaccine efficacy” drops: not in general, but with respect to the barrier offered by vaccines to contagion.

For example, Delta “Hole the vaccines” in the sense that, after about 6 months, even vaccinated people can become infected more easily, with a much lower probability than a non-vaccinated. Once infected, then, that a vaccinated can in turn infect others is another “story”: also in this case the possibility is there, but the probability of it happening drops a lot compared to the data of an unvaccinated.

The vaccine efficacy, therefore, is of two types: towards severe cases or towards infection. To further “complicate” the question is another fact: that effectiveness is not a fixed number nor is it established once and for all. It depends on the type of vaccines, it changes according to the studies carried out (laboratory or real world) and, if measured “in the field”, it changes according to the epidemiological situation of the country, the average age of the study participants, the measurement methods used by scientists.

They are all complex variables that eventually come synthesized in a number and an expression (“vaccine efficacy”) that simplify, but can confuse, if used without explanation and contextualization.

Having said that: what we know so far about Omicron compared to its ability to “puncture vaccines”?

Almost nothing: we can only make assumptions.

– Omicron weakens the ability of vaccines to
protect us from infection?

Possible: it is the first characteristic that the new variant seems to have and the one immediately reported by the World Health Organization (WHO). «WHO considers the Omicron variant to be high risk. We don’t know much but enough to be worried, ”said the President of the European Commission, Ursula von der Leyen. “The new Omicron variant is very contagious and requires urgent action,” the G7 health ministers wrote in a statement. This feature concerning the transmissibility, But, it’s not safe: it is mainly based on the rapid growth of cases in South Africa, where Omicron is advancing much faster than Delta did when it arrived in the country.

Using the analysis on molecular swabs without the S gene (which allows us to assume the presence of Omicron before carrying out the entire sequencing) it seems that Omicron is widespread (and rapidly advancing) even in provinces that are hundreds of kilometers away. on the other (see graphic above). However, the data is not enough to decree Omicron’s greater ability to infect than Delta, especially since infections are in young populations and the country has a very low vaccination rate (36%).

– Omicron weakens the ability of vaccines to
protect us from disease?

Compared to Omicron’s ability to reduce the vaccine efficacy it protects against hospitalizations and deaths there is a cautious optimism: so far no variant has questioned this result. Among the worst was Beta, which however did not have the same diffusion capacity as Delta and therefore remained limited. “That there is a very high probability of a drop in the ability of vaccines to protect against infection, as was the case with Delta, and perhaps a little higher, we have to assume. The problem is to see how much they will protect against the disease and we will know this only in a few weeks, ”said Sergio Abrignani, immunologist of the Technical Scientific Committee (CTS). “Even if there were a decrease – he continued -, it would not be 80% and, if it is more than a certain percentage (which will be established by the health agencies), it will be possible to use a new vaccine in a few months”.

However, also on the data “vaccine efficacy vs serious disease” there are no certainties. The mutations observed on Omicron do not bode well: some are known precisely for evade antibodies, but mutations sometimes work together to make a virus more fearsome, other times they can ‘cancel out’ each other. Not only that: if Omicron were more “bad”, but less contagious than Delta, it probably would not be able to undermine it, as happened to other variants.

What do they say real-world data on this?

Discordant elements come from South Africa: hospitalizations in Gauteng (the region most affected by Omicron) are growing strongly e triplicate in 2 settimane (see graphic above), ma the symptoms reported are judged to be “mild”. The virus spreads – as written – in a relatively young and poorly vaccinated population. Dr Angelique Coetzee, president of the South African Medical Association, said: “There was no need for oxygen. The variant is not causing prominent symptoms. ‘

Meanwhile the European Center for Disease Prevention and Control (ECDC) has written about European positives: «They were asymptomatic or mild. So far, no serious cases or deaths have been reported. ”

Also to understand the level of severity of the infection caused by Omicron – as well as for its contagiousness, and the ability to “puncture” the vaccines, both at the contagion level and at the disease level – will take more time.

December 1, 2021 (change December 1, 2021 | 15:39)

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