Booster Dose of AstraZeneca COVID-19 Vaccine Significantly Increases Levels of Antibodies Against Omicron Variant

The study analyzed blood samples taken from individuals infected with COVID-19, those who had been vaccinated with a 2-dose schedule and a third booster dose, and those who had reported previous infection from other COVID-19 variants of concern.

ChAdOx1-S (Vaxzevria, AstraZeneca) significantly increased levels of antibodies against the omicron SARS-CoV-2 variant following a third dose booster, according to an AstraZeneca press release.

The study analyzed blood samples taken from individuals infected with COVID-19, those who had been vaccinated with a 2-dose schedule and a third booster dose, and those who had reported previous infection from other COVID-19 variants of concern. Samples from 41 individuals who had received 3 doses of ChAdOx1-S were included.

“It is very encouraging to see that current vaccines have the potential to protect against Omicron following a third dose booster,” said study investigator, Sir John Bell, Regius Professor of Medicine, University of Oxford, UK, in the press release. “These results support the use of third dose boosters as part of national vaccine strategies, especially to limit the spread of variants of concern, including omicron.”

Additionally, data from another laboratory study support ChAdOx1-S’s effect against omicron, with individuals vaccinated with 2 doses of ChAdOx1-S retaining neutralizing activity against the variant, although a decrease was seen compared to the original strain, according to AstraZeneca. ChAdOx1-S has also shown a durable T-cell response to multiple variants resulting in a broader response than antibodies alone, which could contribute to protection against COVID-19, according to the study.

In a sub analysis from the COV001 and COV002 trials, a third dose of ChAdOx1-S given at least 6 months after a second dose showed a boost in antibody levels and maintained T-cell response. Further, a third dose resulted in higher neutralizing activity against the alpha, beta, and delta variants compared with a 2-dose regimen, according to the study.

REFERENCE

Vaxzevria significantly boosted antibody levels against Omicron. AstraZeneca. December 23, 2021. Accessed January 4, 2022. https://www.astrazeneca.com/media-centre/press-releases/2021/vaxzevria-significantly-boosted-antibody-levels-against-omicron.html