Preliminary Results Support Feasibility, Immunogenicity of Influenza-COVID-19 Combo Vaccine

Initial phase 1/2 clinical trial results for a combined COVID-19-influenza (CIC) vaccine demonstrate the investigational double immunization is feasible, well tolerated, and produces and immunologic response. Data from the trial were reported April 20, 2022, by manufacturer Novavax at the World Vaccine Congress (WVC) in Washington, DC.

The investigational vaccine combines the company’s COVID-19 vaccine, NVX-CoV2373, and its quadrivalent influenza vaccine candidate, according to a Novavax statement.

The preliminary findings showed that a variety of CIC vaccine formulations induced immune responses in study participants that investigators described in the company statement as “comparable to reference stand-alone flu (for H1N1, H3N2, B-Victoria HA) and stand-alone COVID-19 (for SARS-CoV-2rS antigens) vaccine formulations.”

Phase 1/2 trial participants at 10 sites in Australia (n=642) were healthy adults aged 50 to 70 years who had either been previously infected with SARS-CoV-2 or vaccinated with an initial series of an authorized COVID-19 vaccine at least 8 weeks prior to study enrollment. All participants were randomized to cohorts to evaluate multiple formulations of the 2 vaccines.

The trial’s objective, according to the company statement, was to identify an optimal dose of the combined formulation prompting researchers to use a modeling-based design that would allow more robust fine-tuning (vs traditional approaches) of dose selection for both vaccines.

The modeling results indicate the potential for a combination vaccine to reduce total antigen amount by as much as 50% overall, which would facilitate both product production and delivery.

"We continue to evaluate the dynamic public health landscape and believe there may be a need for recurrent boosters to fight both COVID-19 and seasonal influenza," said Gregory M. Glenn, MD, Novavax president of research and development, in the statement.

"We're encouraged by these data and the potential path forward for a combination COVID-19-influenza vaccine as well as stand-alone vaccines for influenza and COVID-19."

The company's quadrivalent influenza vaccine candidate met primary immunogenicity endpoints in a phase 3 trial published earlier this year in the Lancet and presented at WVC. Novaxax applied in Januaray 2022 for US Food and Drug Admnisitration Emergency Use Authorization for its COVID-19 NVX-CoV2373 vaccine but has yet to receive a response.

Novavax reports that safety and tolerability of the combined formulation was consistent with the individual vaccine reference formulations in the trial. Serious adverse events were rare and judged to be unrelated to the vaccine or its components.

A phase 2 confirmation trial for the CIC is expected to begin by the end of 2022, the statement concludes.