Adenovirus-Based Vaccine Boosted Antibody Levels Against Omicron

England-based AstraZeneca announced a real-world study of the Vaxzevria vaccine significantly boosted levels of antibodies against the Omicron SARS-CoV-2 variant following a third dose booster.

According to new data from this laboratory study led by various researchers published on December 23, 2021, neutralization titers for Omicron were boosted following a third dose with Vaxzevria compared to titers after a second dose.

And the levels seen after the third dose booster were higher than the neutralizing antibodies found in individuals who had been previously infected with and recovered naturally from COVID-19 (Alpha, Beta, Delta variants, and original strain).

The study analyzed blood samples from 41 individuals infected with COVID-19; those vaccinated with a two-dose schedule and a third-dose booster who had reported a previous infection from other COVID-19 variants of concern.

Professor Sir John Bell, Regius Professor of Medicine, University of Oxford, UK, and one of the study investigators, said in a press statement issued on December 23, 2021, "It is very encouraging to see that current vaccines have the potential to protect against Omicron following a third dose booster."

"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."

Data from another laboratory study support Vaxzevria's effect against Omicron, with individuals vaccinated with two doses of Vaxzevria retaining neutralizing activity against Omicron. However, a decrease was seen compared to the original strain.

In other studies, Vaxzevria has been shown to generate a diverse and durable T-cell response to multiple variants resulting in a broader response than antibodies alone, which could protect against COVID-19.

AstraZeneca is also analyzing blood samples from participants in the Company's Phase II/III trial to evaluate neutralizing activity when given as a third dose booster against Omicron for both Vaxzevria and its investigational next-generation COVID-19 vaccine, AZD2816. Data from these studies are expected in 2022.

In summary, 'available data against variants of concern, excluding Omicron, support the use of the third booster with Vaxzevria as part of a homologous or heterologous schedule,' stated AstraZeneca.

Vaxzevria (ChAdOx1-S [Recombinant], formerly AZD1222) was co-invented by the University of Oxford and Vaccitech.

It uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein.

After vaccination, the surface spike protein is produced, priming the immune system to attack the SARS-CoV-2 virus if it later infects the body.

The Vaxzevria vaccine has been granted conditional marketing authorization or emergency use in more than 90 countries. It also has Emergency Use Listing from the World Health Organization, which accelerates the pathway to access in up to 142 countries.

Under a sub-license agreement with AstraZeneca, the vaccine is manufactured and supplied by the Serum Institute of India under the name COVISHIELD.

The study was performed independently by investigators at the University of Oxford. No industry conflicts were identified. The corresponding authors are ren@strubi.ox.ac.uk, dave@strubi.ox.ac.uk, jmongkol@well.ox.ac.uk, gavin.screaton@medsci.ox.ac.uk, gideon.schreiber@weizmann.ac.il.

AstraZeneca is a global, science-led biopharmaceutical company.