Two Studies Assess Pfizer’s Effectiveness Against Omicron

The Omicron variant substantially reduced antibody levels generated by the Pfizer-BioNTech COVID-19 vaccine, according to preliminary results from a South African study that’s still awaiting peer review. These are the first laboratory results to see how a COVID-19 vaccine holds up to Omicron. A team of researchers led by Africa Health Research Institute‘s Alex Sigal tested 14 blood samples from 12 people against a live sample of the Omicron variant. All 12 people were vaccinated, and six were previously infected.

Overall, the scientists found a roughly 40-fold reduction in the levels of neutralizing antibodies, the virus-fighting proteins that play a key role in our immune response, compared with the original version of the virus. Omicron did not evade vaccine protection completely, Sigal wrote on Twitter, meaning there’s still benefit to being vaccinated against this new variant. But the marked reduction in antibodies raises questions of how durable vaccine protection will be against Omicron – namely, whether booster shots will sufficiently ward off disease or if new vaccines may eventually be required. Sigal called it a “very large drop in neutralization of Omicron.”

A good booster probably would decrease your chance of infection, especially severe infection leading to more severe disease,” Sigal said in an online presentation of his results on Tuesday, according to Bloomberg. “People who haven’t had a booster should get one, and people who have been previously infected should be vaccinated.”

Shortly after Sigal announced his team’s results, another group of researchers at Sweden‘s Karolinska Institutet disclosed their own findings that suggested a substantial but less dramatic decline in antibody levels. The Karolinska team found a seven-fold reduction across 17 blood samples. They noted the impact of Omicron varied greatly between samples, and they used a version of Omicron that was artificially made in a lab instead of the live virus. A lead researcher for that group said the findings make Omicron “certainly worse than Delta, but, again, not as extreme as we expected.” The results are not finalized and have not been published in a medical journal. Sigal cautioned on Twitter that the findings “are likely to be adjusted as we do more experiments.”

Source: https://www.sciencealert.com/

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