Pfizer vaccine may be less effective against omicron, says small study

WHAT YOU NEED TO KNOW:

• The Pfizer-BioNTech Covid-19 vaccine may be less effective against the new omicron variant, according to a small study.
• Researchers said people who have recovered from Covid-19 and received a booster shot will likely have more protection from severe disease.
• The small study tested 14 plasma samples from 12 vaccinated people, 6 of whom had Covid-19.

The Pfizer-BioNTech Covid-19 vaccine appears to be less effective against the heavily mutated omicron variant of the coronavirus, according to early data from South Africa posted Tuesday.

Researchers from the Africa Health Research Institute found that there was about a fortyfold reduction in vaccine-induced antibodies that could neutralize the new variant, which has been detected in several countries and in at least 19 states.

The omicron variant appeared to be even more skilled at evading the antibodies generated by the Pfizer vaccine than the beta variant, which was also first identified in South Africa, the researchers said. The beta variant has demonstrated a threefold reduction in neutralization, they wrote.

There are limits to the South African lab study, which was posted online to a preprint server and has not been peer-reviewed. The research is based on blood samples from 12 patients who were vaccinated with the Pfizer vaccine but had not received booster shots. The drop in neutralizing antibodies found in blood samples may not reflect how the variant may behave in a real-world setting.

The lead author on the study, Alex Sigal, a South Africa-based virologist, wrote Tuesday on Twitter that the results could change as researchers conduct more experiments.

The World Health Organization and other top scientists had warned that the new variant, which has 50 mutations, could evade the protection provided by vaccination or natural infection.

Vaccine makers have said they are developing omicron-specific shots if needed. Pfizer-BioNTech has said it could develop a variant-specific vaccine within six weeks and ship initial batches within 100 days, while Moderna has said it can advance a new candidate to trials within 90 days. Johnson & Johnson said it is pursuing a modified vaccine and will progress it as needed.

In the document posted online, the researchers wrote that the antibodies generated from a combination of natural infection and vaccination might be enough to protect against the worst outcomes from the new strain.

“Previous infection, followed by vaccination or booster is likely to increase the neutralization level and likely confer protection from severe disease in Omicron infection,” they said.

Before the data were posted Tuesday, Dr. Anthony Fauci, the White House’s chief medical adviser, said it was too early to know whether the variant causes more severe disease, although early reports suggest it might cause milder illness.

Source: NBC News