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

In recent days, a number of studies have been published that attempt to measure the efficacy of covid-19 vaccines against the omicron variant. The number of these studies is very limited and, above all, the number of patients studied is very limited. This can be considered their first weakness.

What can be measured at the moment is the capacity of the antibodies generated by the vaccines, by the booster dose given to individuals who have been infected and by the third dose given to vulnerable people. A priori, each of the mutations in the spicule protein has a possible action that has an impact on the ability to infect, and not only on the binding of neutralising antibodies. The process is much more complicated because the whole set of these mutations and their possible interactions, hitherto unknown, must be taken into account.

The studies that are currently appearing measure whether or not the antibody titre decreases against the new variant, but the effectiveness of the vaccine cannot be assessed on this basis alone. The system for measuring these variations in antibody titres is not linear. A 40-fold difference, for example, does not mean that there is a 40-fold reduction compared to other variants.

Finally, the use of different technologies can vary the results. The value of neutralising antibody titres generated against the infectious omicron virus is not the same as those generated against a pseudovirus.

We cannot evaluate in the same way the values shown in the different articles that are appearing because the numbers can mean very different concepts, biological activity, viral escape, etc. Obviously it is also not possible to evaluate the effectiveness of vaccines and draw conclusions about how well, or how poorly, they will work in real conditions.

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