Long-term safety and efficacy of COVE study open-label and booster phases (preprint)

Vaccination with two injections of mRNA-1273 (100-μg) was shown to be safe and efficacious at preventing coronavirus disease 2019 (COVID-19) in the Coronavirus Efficacy (COVE) trial at completion of the blinded part of the study. We present the final report of the longer-term safety and efficacy data of the primary vaccination series plus a 50-μg booster dose administered in Fall 2021. The booster safety profile was consistent with that of the primary series. Incidences of COVID-19 and severe COVID-19 were higher during the Omicron BA.1 than Delta variant waves and boosting versus non-boosting was associated with significant reductions for both. In an exploratory Cox regression model adjusted for time-varying covariates, a longer interval between primary vaccination and boosting was associated with a significantly lower incidence of COVID-19 during the Omicron BA.1 wave. Boosting elicited greater immune responses against ancestral SARS-CoV-2 than the primary series, irrespective of prior SARS-CoV-2 infection.  ClinicalTrials.gov: NCT04470427

Bivalent and Monovalent SARS-CoV-2 Variant Vaccine Boosters Improve coverage of the known Antigenic Landscape: Results of the COVID-19 Variant Immunologic Landscape (COVAIL) Trial (preprint)

Vaccine protection against COVID-19 wanes over time and has been impacted by the emergence of new variants with increasing escape of neutralization. The COVID-19 Variant Immunologic Landscape (COVAIL) randomized clinical trial (clinicaltrials.gov NCT 05289037) compares the breadth, magnitude and durability of antibody responses induced by a second COVID-19 vaccine boost with mRNA (Moderna mRNA-1273 and Pfizer-BioNTech BNT162b2), or adjuvanted recombinant protein (Sanofi CoV2 preS DTM-AS03) monovalent or bivalent vaccine candidates targeting ancestral and variant SARS-CoV-2 spike antigens (Beta, Delta and Omicron BA.1). We found that boosting with a variant strain is not associated with loss in neutralization against the ancestral strain. However, while variant vaccines compared to the prototype/wildtype vaccines demonstrated higher neutralizing activity against Omicron BA.1 and BA.4/5 subvariants for up to 3 months after vaccination, neutralizing activity was lower for more recent Omicron subvariants. Our study, incorporating both antigenic distances and serologic landscapes, can provide a framework for objectively guiding decisions for future vaccine updates.