Reacción a "Reaction to early laboratory data on how antibodies respond to the omicron variant"

Preliminary data published to date suggest a greater antigenic impact of the omicron variant compared to other variants of concern that have been selected as a result of the evolution of the virus (beta, delta).

There is some discrepancy, to some extent understandable, as to the magnitude of this antigenic impact.

This may be due to the different vaccination schedules tested, but also to the methodology used in the different studies. Both natural isolates and pseudovirus systems have been used which, although previous studies to date have shown similar trends, do not always reflect the same degree of neutralisation.

In addition, neutralisations are performed in different cell lines, some of them specifically modified to increase their susceptibility to SARS-CoV-2 infection. These cell lines generally overexpress the ACE2 cellular receptor and this can lead to a bias in the degree of neutralisation that is appreciable between variants whose receptor binding regions (RBD) show very different properties.

Given the high number of mutations detected in the omicron RBD, it is expected that its ACE2 binding properties are substantially modified compared to other variants.

It is important to note that these studies only refer to the impact of omicron on the antibody response induced after infection or vaccination. Based on the analysis of the omicron sequence, the T-cell response should not be so severely compromised. Therefore, it is expected that the vaccines administered will maintain a significant level of efficacy in preventing serious infections, not so much in reducing the level of infections and reinfections.