How to interpret the coming data on Omicron and Covid immunity - STAT

At some point in the next few weeks, scientists will start releasing data from lab experiments that can help illuminate just how much of a threat the Omicron variant poses to existing Covid-19 vaccines and our immunity.

Together, these lab studies, combined with the clinical outcomes of patients infected with the variant, will help experts form a broader understanding of Omicron’s impact — and whether, if it takes off globally, we might need to adapt our vaccines.

Key results will come from studies that involve testing how well antibodies in the blood of people who’ve been vaccinated or recovered from Covid-19 stand up against Omicron.

Soon, research teams will report findings such as a drop in neutralizing activity against the variant — it could be, say, a fivefold or 50-fold drop — or some percentage decline in the levels, or titer, of neutralizing antibodies.

But these studies measure how well just one component of the immune system — neutralizing antibodies — recognizes the variant in question.

Indeed, experience with past variants suggests people can lose a decent amount of neutralizing activity and still be well-protected against more serious outcomes.

A fourfold or fivefold drop is not much to worry about, Thackray said; even a 50-fold drop could be OK if the starting point for the neutralization levels was really high.

But if it’s a, say, 100-fold drop or more, “then you’re really relying on T cell immune responses” and other parts of the immune system that can pick up the new variant, Thackray said.

(Scientists have lamented that one consequence of the travel restrictions imposed on South Africa — where some of the first Omicron cases were detected — is that they could delay the sharing of the variant virus with researchers around the world.).

There will be results on antibodies from prior Covid-19 infections, from the different vaccines, and potentially from people who have received boosters.

If more breakthrough infections are leading to hospitalizations or deaths, researchers will try to track which vaccines those people received and when, to understand if one shot is more affected by Omicron than others or is showing worrisome waning.

These studies will take time, both because it takes weeks for hospitalizations and deaths to occur after infections, and because there have only been a few hundred cases of Omicron documented globally so far.

Even if Omicron is able to evade immunity to concerning levels, regulators and vaccine makers wouldn’t adapt the shots to better match the variant unless it also became dominant globally

Experts will want to see whether Omicron takes off in other countries to get a better sense of any advantage over Delta

Experts will also be keeping a close eye on the neutralizing activity against Omicron after a booster dose

If that holds true, and booster doses enable people to withstand even a variant as mutated as Omicron, it could indicate that vaccines don’t need to be tweaked