Novavax has reported that its recombinant nanoparticle protein-based Covid-19 vaccine, NVX-CoV2373, met the primary immunogenicity endpoint in the paediatric expansion of its Phase III PREVENT-19 trial.

According to the findings, the vaccine showed an overall efficacy of 80% when the Delta variant of the SARS-CoV-2 virus was predominant in the US. 

The vaccine’s efficacy was similar across age groups of adolescents and adults.

Furthermore, NVX-CoV2373 had an efficacy of 82% against the Delta variant. 

The randomised, placebo-controlled, observer-blinded trial analysed the safety, immunogenicity and efficacy of NVX-CoV2373 versus placebo.

It enrolled 2,247 adolescent subjects of the age 12 to 17 years at 73 locations in the US.

Post hoc analyses data showed that adolescents who received two doses of the vaccine had strong immune responses, including IgG responses against spike proteins of various SARS-CoV-2 variants, and were two- to three-fold greater than in adults.

Initial safety results showed that the vaccine was well-tolerated in paediatric subjects without any safety signals reported.

The neutralising antibody responses in paediatric subjects were found to be non-inferior to those seen in young adults of the age 18 to 26 years in the PREVENT-19 trial. 

Neutralising antibody responses to wild-type of the virus were nearly 1.5-fold greater in adolescents compared to young adults, thereby meeting Food and Drug Administration-defined criteria.

Novavax chief medical officer Filip Dubovsky said: “We believe the Novavax vaccine offers a differentiated technology and option for this younger population given its established protein-based technology already used in other vaccines, and the positive responses demonstrated against variants.”

The company anticipates making submissions to regulatory agencies worldwide for a paediatric indication in adolescents of the age 12 to 17 years during the first quarter of this year. 

Novavax also plans to commence further studies analysing younger individuals across the globe during the second quarter.

In December last year, Novavax reported that two doses of NVX-CoV2373 demonstrated cross-reactive immune responses against Omicron and other variants.