Omicron Breakthrough Infection After Heterologous Prime-Boost Vaccination Induces a Vigorous Antibody Response

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• The SARS-CoV-2 Omicron variant typically causes mild or asymptomatic infections.
• Omicron's immunogenicity appears limited, especially in unvaccinated individuals.
• Understanding immune responses post-Omicron infection in vaccinated populations is crucial.

Purpose of the Study:

• To investigate the neutralizing antibody response in vaccinated individuals after Omicron breakthrough infection.
• To assess the immunogenicity of the SARS-CoV-2 Omicron variant in a healthcare worker cohort.

Main Methods:

• Study population: Healthcare workers vaccinated with Sputnik V (2 doses) and ChAdOx1 booster.
• Exposure: Breakthrough infection with the SARS-CoV-2 Omicron variant.
• Assessment: Measurement of neutralizing-antibody response.

Main Results:

• Vaccinated healthcare workers mounted a vigorous neutralizing-antibody response following Omicron breakthrough infection.
• The study observed a robust immune response despite the Omicron variant's generally lower immunogenicity.

Conclusions:

• Sputnik V and ChAdOx1 vaccination elicits a strong antibody response upon Omicron breakthrough infection.
• This suggests that existing vaccination protocols can induce protective immunity against Omicron variant infections.