Having received both doses, performance against Covit-19 was undoubtedly reduced, but the most important protection: an update on what we know about the action of vaccines against the delta variant, the progress of which is of concern across the planet.
Come SITTLER / POOL / AFP
Reduced performance …
Many laboratory studies have shown that the delta variant (formerly known as the “Indian variant”) is more resistant to vaccines than other types (this is called “immune escape”).
One of these studies was carried out by British authorities and published in the medical journal The Lancet in early June. His results: In those vaccinated with two-dose Pfizer / Bioentech, the neutralization of antibodies was almost six times lower than in the presence of a historical strain of the virus in the presence of delta variation (which was used to develop vaccines).
In comparison, this reduction is 2.6 times that of the alpha variant (or “English variant”), and 4.9 times that of the beta variant (“South African”).
Another study conducted in France by the Institute Pastor concludes that neutralizing antibodies produced by vaccination with Pfizer / Bioentech are three to six times less effective against the delta variant than the alpha variant.
… but performance though
Although this is an important symptom, laboratory-measured antibody levels are not sufficient to determine the effectiveness of a vaccine. In fact, it does not take into account the cellular immunity (due to cells called lymphocytes) which is the other part of the immune response.
So the importance of seeing what happens in real life. The first results of the actual population are promising.
Vaccination with Pfizer / Bioendech and Astrogeneneka will help prevent hospitalization when it comes to the delta variant and the alpha variant, according to data released by British authorities on Monday.
Two doses of 96% (for Pfizer / Bioentec) and 92% (for AstraZeneca) prevent hospitalization due to delta variability, according to the study, with 14,000 participants.
Previous official English data contacted at the end of May reached comparable results for less severe forms of the disease.
Two weeks after the second dose, the Pfizer / Bioentech vaccine is 88% effective against the symptomatic form of covit caused by the delta variant, which is 93% when it comes to the alpha variant. For its part, AstraZeneca shows 60% and 66% efficacy against these types.
Similar information was released by Scottish authorities on Monday in The Lancet.
Finally, Russian vaccine Spotnik V designers on Tuesday promised on Twitter that it would be “more effective against delta variant” than any other vaccine at this point. However, they did not publish their data and were sent to a medical journal accordingly.
One dose is not enough
In the lab or in real life, studies converge at one point: getting a single dose of vaccine offers only limited protection against delta variation.
The variant, “After a single dose of Pfizer / Bioendech, 79% of people had a detectable antibody response to the original strain (virus), but this was at least 50% for the alpha variant and at least 32% and 25% beta for the delta variant” was published in The Lancet in early June. Completes laboratory study.
According to the Pastor Institute, a single dose of AstraZeneca may be “slight or ineffective” against the delta variant.
Confirmed trends in real life: According to British officials, one dose of the two vaccines is only 33% effective in preventing the symptomatic form of the disease caused by the delta variant (and 50% when it comes to the alpha variant).
On the other hand, the first dose of Pfizer / Bioentech already offers the highest protection (94%), avoiding hospitalization due to delta variation.
Of all the approved vaccines, Jansen can only be prescribed with a single dose. However, specific information on its effectiveness against the delta variant is not available.
The British government decided on Monday to reduce the gap between doses, fearing that people would not be adequately protected against delta variation if the vaccine was not completed. For people over 40, it can take anywhere from 12 to 8 weeks.
In France, this interval can now be reduced to 3 weeks (at least 5 weeks ago) for Pfizer / Bioentech and Modernna vaccines.
Then?
According to British officials, to protect against the onset of the delta variant, which is 60% more prevalent than alpha, scientists are emphasizing the importance of a complete vaccine, in both sizes.
According to Jean-Franசois Delphra்சi, president of the French Science Council, the creation of these “vaccinated individuals” has a second goal: to protect, only partially, or not, to prevent the emergence of other variations among the population.
Because beyond the alpha variant, what worries scientists is the emergence of future vaccines that will resist vaccines.
“Increasing the proportion of the population vaccinated by current vaccines is safe and effective, which is an important strategy to reduce the appearance of new strains and to end the Govt epidemic,” the journal Nature underlined in its June 10 issue.
However, epidemiologist Antoine Flaholt told AFP that “we should not base everything on the vaccine.”
He believes it is important to “keep the virus circulation to a minimum” through all other control measures (barrier gestures, identification of cases to break transmission chains, control measures where necessary …). This is because the more the virus spreads, the more likely it is to change, and therefore lead to other types.