Everything known in the world about coronavirus vaccines and how to treat the Delta variant

Faced with the Delta variant of the coronavirus, the progression of which in the world is worrying, vaccines are less effective but protection against disease is still important as long as both doses are received.

Several laboratory studies show that the Delta variant (formerly called the “Indian variant”) seems to be more resistant to vacciness than other mutations. This is called “immune breakout”.

According to one of these reports, carried out by the British authorities and published in early June in The Lancet, in people vaccinated with the two doses of Pfizer / BioNTech, the level of neutralizing antibodies is almost six times lower in the presence of the Delta variant than with the original strain, which was used to develop the vaccines.

In comparison, this reduction is 2.6 times compared to the Alpha variant (“British”), and 4.9 times compared to the Beta variant (“South Africa”).

Another study, carried out by the Institut Pasteur in France, concludes that the neutralization of the antibodies after receiving the vial of Pfizer / BioNTech are three to six times less effective against the Delta variant than against the Alpha.

Antibody levels recorded in the laboratory are an essential indicator, but they are not sufficient to determine the effectiveness of a vaccine. The other facet of the immune response is not taken into account, cellular immunity.

Hence the importance of analyzing what happens in real life. Yes the results are rather reassuring.

The studies

According to data released Monday by British authorities, vaccination with Pfizer / BioNTech and AstraZeneca it’s just as effective to avoid hospitalization for Delta and Alpha variants.

Two doses allow 96% to avoid (for Pfizer / BioNTech) and 92% (for AstraZeneca) hospitalization due to the Delta variant, according to this study of 14,000 people.

Previous data from the UK authorities showed similar conclusions for less severe forms of the disease.

Two weeks after the second dose, the Pfizer / BioNTech vaccine eonly 88% effective against the symptomatic form of covid-19 due to the Delta variant, against 93% when it comes to the Alpha variant. For its part, AstraZeneca shows an effectiveness of 60% and 66% against these mutations.

The creators of the Russian vaccine Sputnik V claimed on Twitter on Tuesday that their drug was “more effective against the Delta variant” than anyone, but they haven’t released their data.

The studies converge on one point: a single dose provides limited protection against the Delta variant.

“After a single dose of Pfizer / BioNTech, 79% of people had a detectable antibody response against the original strain, but this fell to 50% for the Alpha variant, 32% for the Delta variant and 25%. for the Beta variant “, concludes the laboratory study published in June in The Lancet.

According to research by the Institut Pasteur, a single dose of AstraZeneca would be “little or not effective” against the Delta variant.

These trends are confirmed in real life: according to the British authorities, a single dose of either of the two vaccines has an efficiency of 33% to prevent the symptomatic form of the disease caused by Delta (and 50% for the Alpha variant).

Complete vaccination

Of all the authorized vaccines, only Janssen’s is a single-dose vaccine. Not now data is available on your protection against the Delta variant.

To stop the spread of this variant, 60% more transmissible than Alpha according to the British authorities, scientists insist on the importance of a complete vaccination, with two doses.

Create this “vaccinated block”, According to the words of the President of the French Scientific Council Jean-François Delfraissy, it has a second objective: to prevent other variants from emerging from the partially or not protected population.

The perspective that worries the most is the appearance of other mutations of the virus, more resistant to vaccines.

But, “You don’t have to base everything on vaccination”epidemiologist Antoine Flahault told AFP.

According to him, it is crucial “Keep the circulation of the virus very low”, by other control measures (barrier gestures, case detection, restriction measures, etc.), since the more the virus circulates, the more likely it is to mutate and create other variants.

Source: AFP

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