It spreads much faster, does not seem to cause more serious forms ... but is it resistant to vaccines?
Since the Omicron variant was presented to the world less than two weeks ago, this is the question scientists around the world have been trying to answer.
Tuesday evening, the World Health Organization had estimated that there was "no reason to doubt" the effectiveness of the vaccines.
The first results were published by three teams of researchers (in South Africa, Sweden and Germany), between Tuesday evening and Wednesday morning.
Either in record time.
"Given the circumstances, we think it is essential to publish the data immediately and to explain what are the warnings to keep in mind at the moment", justified Ben Murrell, of the Karolinska Institute, in Sweden.
Major NB: this is preliminary data.
Given the circumstances, however, we feel it critical to release data right away, and explain current caveats that we can later iron out and investigate.
Link here: https://t.co/ddYwqw5QR5 (2 / n).
- Ben Murrell (@BenjMurrell) December 7, 2021
These very preliminary studies focus on the levels of neutralizing antibodies, one of the weapons of our immune system.
And their results converge on the fact that these rates seem to drop quite significantly.
"Immune erosion"
According to work carried out by researchers at the Africa Health Research Institute, involving only 12 people, the potency of these neutralizing antibodies in people doubly vaccinated with Pfizer would be 40 times less against Omicron than against the original virus.
"It's not great, but not a disaster either," commented British epidemiologist Meaghan Kall, member of the UK Health Security Agency, recalling that Delta had already caused a drop in the potency of the immune response. .
Many researchers prefer to speak of "erosion" rather than "escape" immune, so as not to suggest that vaccines become totally ineffective.
Read also Omicron more contagious but less virulent?
Why this hypothetical scenario might be good news
The team from the Karolinska Institute, for its part, found a factor of 7 for the reduction in the neutralizing power of antibodies against Omicron.
"Which certainly makes it worse than Delta, but not as much as we feared," one of its members, Ben Murrell, said on Twitter.
These two studies "are rather positive with certainly a significant drop in protection, but still the presence of some residual protection", comments virologist Yannick Simonin to Le Parisien.
Frankfurt-based scientist Sandra Ciesek tweeted similar lab results: strong reduction in antibody potency, but no total immune escape.
“Worse than Delta, but not as much as we feared”?
What about a booster dose?
The first study mentioned, that of the Africa Health Research Institute, suggests that people who have been infected in the past in addition to having been vaccinated with Pfizer retain good protection.
The administration of a booster dose has not been examined, but it can be assumed that the same phenomenon would be observed with fairly robust vaccine efficacy.
The work relayed by the German scientist is less optimistic about the power of three doses of vaccine against Omicron.
“While the protection remains much stronger with than without the booster, it seems to remain relatively low.
But these are partial studies, on few samples and not yet complete, ”insists Yannick Simonin.
unsere ersten Daten zur
Neutralization von Omicron versus Delta sind fertig: 2x Biontech, 2x Moderna, 1xAZ / 1x Biontech nach 6 Monaten 0% Neutralization bei Omicron, auch 3x Biontech 3 Monate nach Booster nur 25% NT versus 95% bei Delta.
Bis zu 37fache Reduktion Delta vs.
Omicron pic.twitter.com/w0gHww26sg
- Sandra Ciesek (@CiesekSandra) December 8, 2021
Anyway, it should be kept in mind that neutralizing antibodies are only one facet of our immune system.
Other elements, such as T lymphocytes, can also be protective, especially against severe forms.
“In summary, the vaccine loses its effectiveness on its antibody side, but the booster probably at least partially compensates for this drop.
We will have to wait for results on the cellular response (but it is much longer), and especially those from real life in South Africa, ”says Yannick Simonin.
Like other scientists, he expects that a new version of the vaccines will be needed to bring their effectiveness back to a very high level.
