Omicron Not Wholly Evading Pfizer COVID Vaccine in Study Gives Scientists Cause for Hope

A new preliminary study into how the Omicron variant responds to Pfizer vaccines has been released.

The study, undertaken by South Africa-based researcher Alex Sigal and colleagues, suggests that Omicron does not completely evade the protection offered by COVID vaccines.

However, as many scientists had previously suggested, the study also showed that the Pfizer vaccine was much less effective at neutralizing Omicron than an older version of the SARS-CoV-2 virus, showing a roughly 40-fold decline in neutralization activity.

The results of the study have not yet been peer-reviewed. They are due to be published online on the pre-print repository medRxiv in the coming days.

Scientists have reacted to the study's results, some with tentative optimism.

On Twitter, Sigal, a researcher at the Africa Health Research Institute and associate professor at the University of KwaZulu-Natal, wrote that the results were "better than I expected of Omicron" and said the fact that the variant does not completely escape vaccines "means it's a tractable problem with the tools we got."

However, the study does not suggest that Omicron is not a threat. "[Omicron] certainly escapes," Sigal told CNN. "It is certainly bad. But it looks to me like there are ways of dealing with it."

Muge Cevik, a clinical lecturer in infectious diseases and medical virology at the University of St Andrews in Scotland, echoed the point.

"We've been waiting for these results. I have to say it's better than I expected overall," she wrote on Twitter. "Yes, it means we will see more breakthrough infections with Omicron, but hybrid immunity holds pretty well and hopefully we will see similar data with boosted antisera."

A combination of immunity gained from infection and the vaccine is considered hybrid.

It's still not clear how the results of the early study translate to vaccines in the real world. In addition, the study was small, involving samples from 12 double-vaccinated people.

"For those who'd been previously infected with COVID-19 and who had also been vaccinated, considerable immune protection was retained," Dr. Dianne Sika-Paotonu, senior lecturer of pathology and molecular medicine at the University of Otago Wellington in New Zealand, told the Science Media Centre regarding the study.

But she added that more information was still needed about Omicron, including whether or not it causes more severe disease compared to Delta.

Florian Krammer is a professor at the department of microbiology at the Icahn School of Medicine at Mount Sinai. He said on Twitter that his opinion of Omicron has not changed following the results of the study, which he said showed that "little" neutralizing activity against Omicron was left in vaccinated people.

"However, people who were infected and then vaccinated did have residual neutralizing activity despite a drastic reduction," he added. "This certainly also bodes well for vaccinated individuals who received their booster dose."

Late in November, the Centers for Disease Control and Prevention (CDC) strengthened its booster dose recommendation after the appearance of the Omicron variant to state that everyone aged 18 and older should get one once they are six months past their second Pfizer or Moderna shot or two months past their Johnson & Johnson vaccine.

This week, White House COVID-19 response coordinator Jeff Zients said the daily rate at which people were getting booster doses in the country had reached its highest level.

COVID vaccine
A stock photo shows a health worker holding a vial labeled "COVID-19." Researchers are working to find out more about the Omicron variant. Wavebreakmedia/Getty