Updated results from an ongoing Phase 3 clinical trial in the US have shown Moderna's COVID-19 vaccine to be 90 per cent effective against all cases of the disease, and greater than 95 per cent against severe cases.

While the updated cases show continued strong efficacy of the vaccine, the efficacy represents a marginal drop from an earlier figure of 94.1 per cent published in The New England Journal of Medicine in December. The ongoing study involves more than 30,000 people across the US. The new results are based on 900 adjudicated cases of COVID-19 as of April 9. The previous study was based on 185 cases. The US-based biotechnology company also said that results from a preclinical study of its COVID-19 variant-specific vaccine candidates showed that the variant-specific booster vaccine candidates (mRNA-1273.351 and mRNA-1273.211) increase neutralising titers against SARS-CoV-2 variants of concern.

"The Moderna team continues to make important progress with our COVID-19 vaccine. We are looking forward to having the clinical data from our variant-specific booster candidates, as well as clinical data from the Phase 2/3 study of our COVID-19 Vaccine in adolescents", Stephane Bancel, Chief Executive Officer of Moderna, said in a statement. "The new preclinical data on our variant-specific vaccine candidates gives us confidence that we can proactively address emerging variants. Moderna will make as many updates to our COVID-19 vaccine as necessary until the pandemic is under control". Moderna has so far delivered approximately 132 million doses of its COVID-19 vaccine globally.

New preclinical data on the company's variant-specific booster vaccine candidates have been submitted as a preprint to bioRxiv and will be submitted for peer-reviewed publication, Moderna said. These variant-specific vaccine candidates include mRNA-1273.351, which is more specifically targeted against the SARS-CoV-2 variant known as B.1.351 first identified in South Africa, and a multivalent booster candidate, mRNA-1273.211, which combines mRNA-1273 (Moderna's authorised vaccine against ancestral strains) and mRNA-1273.351 in a single vaccine.