COVID-19 Vaccines Induce Lower Antibodies Against Omicron Variant: Study

A nurse prepares the Oxford-AstraZeneca COVID-19 vaccine in a file photo. Pedro Pardo/AFP via Getty Images

A lower level of antibodies against the Omicron virus variant is triggered by COVID-19 vaccines, researchers said in a new study.

Using blood samples from people who received two doses of the Oxford-AstraZeneca vaccine or the Pfizer-BioNTech jab, researchers with the University of Oxford found “a substantial fall” in neutralizing antibodies, with evidence of some people failing to have any.

“This will likely lead to increased breakthrough infections in previously infected or double vaccinated individuals, which could drive a further wave of infection,” the authors wrote in the preprint study.

Omicron is a variant of the CCP (Chinese Communist Party) virus, also known as SARS-CoV-2, which causes COVID-19. The variant was discovered by scientists in South Africa last month, and dates back to at least October, according to genomic sequencing of positive tests.

Early studies, including one from Pfizer and its partner, point to primary vaccination regimes having a dramatically lower effect in terms of preventing COVID-19 infections.

“Although different methodologies and types of selected sera have been used, these results consistently show a reduced neutralization capacity of sera from vaccine recipients and convalescent sera against the Omicron virus as compared to other SARS-CoV-2 variants,” the European Center for Disease Prevention and Control said in a recent brief.

Some research suggests a booster dose can restore some of the lost protection while others indicate natural immunity, or the defense bestowed from recovery, isn’t as good against Omicron infection, though the drop in protection has not been as pronounced.

Levels of antibodies are the primary measure of protection against infection.

Much more important, though, is protection against severe disease, since many COVID-19 cases are detected with no or mild symptoms.

The University of Oxford said their study did not show that Omicron has a higher potential to cause severe disease among the vaccinated.

“These data are important but are only one part of the picture. They only look at neutralizing antibodies after the second dose, but do not tell us about cellular immunity, and this will also be tested using stored samples once the assays are available,” Matthew Snape, a pediatrics and vaccinology professor at the university who co-authored the study, said in a statement.

Emerging data indicate that Omicron is more transmissible than earlier strains but that it does not cause more severe disease. The balance of the data out so far indicate it actually causes more mild cases on average than Delta, the dominant strain in the United States.

Still, experts say further study is needed to ascertain aspects of Omicron, and the first death linked to the variant was reported in the United Kingdom on Monday. It wasn’t clear whether the individual had been vaccinated or not.