Comparative effectiveness of four COVID-19 vaccines, BNT162b2 mRNA, mRNA-1273, ChAdOx1 nCov-19 and NVX-CoV2373 against SARS-CoV-2 B.1.1.529 (Omicron) infection.

Background: There is limited data directly comparing the effectiveness of different COVID-19 vaccines.

Methods: We compared rates of SARS-CoV-2 Omicron BA.1/2 infection during March to May 2022 in Australian adults who had received one of four COVID-19 vaccines in the last 14-63 days as either a primary course or a booster dose using Cox proportional hazards models adjusting for age and other characteristics.

Results: As a primary course, over 2318 person-years and 1033 infections, compared to recipients of BNT162b2 mRNA vaccine, adjusted hazard ratios for SARS-CoV-2 infection were 1.03 (95%CI 0.82-1.30), 1.19 (0.95-1.49), 1.70 (1.46-1.97) for respectively mRNA-1273, ChAdOx-1 nCov-19 and NVX-CoV2373. For the booster dose, over 154,984 person-years and 93,580 infections the respective adjusted hazard ratios compared to BNT162b2 mRNA vaccine were 1.02 (95%CI 1.00-1.04), 1.20 (1.10-1.32), 1.39 (1.20-1.60).

Conclusions: Our findings suggest relatively higher effectiveness of ancestral strain mRNA vaccines against SARS-CoV-2 Omicron infection than viral vector and protein subunit vaccines and provide clinical confirmation of immunological data on differences in COVID-19 vaccine performance.