Bivalent mRNA vaccine targeting S-protein (CureVac)

On September 2, 2022, bivalent COVID‐19 mRNA vaccines, were recommended to address reduced effectiveness of COVID‐19 monovalent vaccines during SARS‐CoV‐2 Omicron variant predominance.

Using national pharmacy‐based SARS‐CoV‐2 testing program data from January 15 to September 11, 2023, this test‐negative, case–control design study assessed bivalent COVID‐19 vaccine effectiveness (VE) against symptomatic infection.

VE against symptomatic infection of a bivalent dose between 2 weeks and 1 month after bivalent vaccination ranged from 46% (95% CI: 38%–52%) for those aged ≥ 65 years to 61% (95% CI 41%–75%) for those aged 12–17 years.

Bivalent vaccines protected against symptomatic infection. However, effectiveness waned over time, emphasizing the need to stay up to date with COVID‐19 vaccination.

The effectiveness of booster bivalent vaccines against the Omicron variant, particularly amongst older patients, remains uncertain.

We sought to compare the relative effectiveness of a fourth dose of vaccine using bivalent messenger ribonucleic acid (mRNA), by comparing patients who had and had not received this dose.

We conducted a matched retrospective cohort study to assess the risk of COVID-19 infection, hospitalization and death of people aged >60 years with four doses as compared to those with only three doses. Cox proportional hazard regression models were used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs). We adjusted by age, sex, nursing-home, comorbidities, primary care setting and previous episodes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. We also investigated the impact of prior SARS-CoV-2 infection within each cohort, using the same methodology.

The administration of a fourth bivalent mRNA vaccine dose conferred significant additional protection against COVID-19 infection (HR: 0.479; 95% CI: 0.454–0.506), hospitalization (HR: 0.393; 95% CI: 0.348–0.443) and 30-day mortality (HR: 0.234; 95% CI: 0.171–0.318), as compared to individuals who had received only a third monovalent vaccine dose. In both cohorts, a prior history of COVID-19 infection involves lower risk of COVID-infection, hospitalization and death.

During the period of Omicron predominance, receiving a bivalent booster vaccine as a fourth dose, as compared to receiving only three doses of a monovalent mRNA vaccine, provides significant extra protection against COVID-19 infection, hospitalization and mortality. Antecedents of SARS-CoV-2 prior to vaccination involves a notable reduction in the above COVID-19 outcomes.