Estimated Effectiveness of a Primary Cycle of Protein Recombinant Vaccine NVX-CoV2373 Against COVID-19
Authors: Mateo-Urdiales Alberto , Sacco Chiara , Petrone Daniele , Bella Antonino , Riccardo Flavia , Del Manso Martina , Bressi Marco , Siddu Andrea , Brusaferro Silvio , Palamara Anna Teresa , Rezza Giovanni , Pezzotti Patrizio , Fabiani Massimo ,   Italian National COVID-19 Integrated Surveillance System and the Italian COVID-19 vaccines registry, Boros Stefano , D'Ancona Fortunato (Paolo) , Di Benedetto Corrado , Filia Antonietta , Rota Maria Cristina , Tallon Marco , Vescio Maria Fenicia , Petrucci Antonia , La Bianca Michele , Mignuoli Anna Domenica , Buono Pietro , Massimiliani Erika , Barbone Fabio , Vario Francesco , Sticchi Camilla , Cereda Danilo , Pompili Marco , Sforza Francesco , Bertoli Pierpaolo , Benetollo Pier Paolo , Pasqualini Chiara , Cisceglia Lucia , Palmas Maria Antonietta , Addario Sebastiano Pollina , Balocchini Emanuela , Tosti Anna , Ruffier Mauro , Da Re Filippo , Battilomo Serena , Proietti Valeria , Odio Camillo , Recine Michele , Ruberto Innocenza , Ascione Salvatore , Bisogno Massimo , Miserendino Gandolfo , Navacchia Massimiliano , Del Frate Beatrice , Cau Emanuela , Baiocchi Diego , Fusco Danilo , Gallo Domenico , Marchetti Maria Rosa , Conforti Diego , Trentini Carlo , Ruggeri Antonino , Ladalardo Concetta , Albano Nehludoff , Corona Marco , Lombardi Paolo , Iacono Massimo , Angori Paolo Bruno , Belardinelli Andrea , Solfiti Milena , Fioraso Stefano , Poma Chiara , Raccanello Nadia 
Published: October 2023

Importance

Protein recombinant vaccine NVX-CoV2373 (Novavax) against COVID-19 was authorized for its use in adults in late 2021, but evidence on its estimated effectiveness in a general population is lacking.

Objective

To estimate vaccine effectiveness of a primary cycle with NVX-CoV2373 against SARS-CoV-2 infection and symptomatic COVID-19.

Design, Setting, and Participants

Retrospective cohort study linking data from the national vaccination registry and the COVID-19 surveillance system in Italy during a period of Omicron predominance. All adults starting a primary vaccination with NVX-CoV2373 between February 28 and September 4, 2022, were included, with follow-up ending on September 25, 2022. Data were analyzed in February 2023.

Exposures

Partial (1 dose only) vaccination and full vaccination (2 doses) with NVX-CoV-2373.

Main Outcomes and Measures

Notified SARS-CoV-2 infection and symptomatic COVID-19. Poisson regression models were used to estimate effectiveness against both outcomes. Adjusted estimated vaccine effectiveness was calculated as (1 − incidence rate ratio) × 100.

Results

The study included 20 903 individuals who started the primary cycle during the study period. Median (IQR) age of participants was 52 (39-61) years, 10 794 (51.6%) were female, and 20 592 participants (98.5%) had no factors associated with risk for severe COVID-19. Adjusted estimated vaccine effectiveness against notified SARS-CoV-2 infection in those partially vaccinated with NVX-CoV2373 was 23% (95% CI, 13%-33%) and was 31% (95% CI, 22%-39%) in those fully vaccinated. Estimated vaccine effectiveness against symptomatic COVID-19 was 31% (95% CI, 16%-44%) in those partially vaccinated and 50% (95% CI, 40%-58%) in those fully vaccinated. Estimated effectiveness during the first 4 months after completion of the primary cycle decreased against SARS-CoV-2 infection but remained stable against symptomatic COVID-19.

Conclusions and Relevance

This cohort study found that, in an Omicron-dominant period, protein recombinant vaccine NVX-CoV2373 was associated with protection against SARS-CoV-2 infection and symptomatic COVID-19. The use of this vaccine could remain an important element in reducing the impact of the SARS-CoV-2 pandemic.