Moderna’s Single-Dose COVID-19 and Flu Vaccine Shows Promise

Although we might hope COVID-19 is behind us, the virus persists. Health experts continue to recommend annual vaccinations for both COVID-19 and influenza. High hospitalization rates for COVID-19 in the recent winter served as a reminder of SARS-CoV-2’s potential to cause serious illness.

However, a single shot might soon address this need. Moderna announced on June 10th that its combined COVID-19/influenza shot produced stronger immune responses to SARS-CoV-2 and influenza compared to existing, separate vaccines.

Both components of the shot are currently in the experimental stage. The COVID-19 part utilizes a slightly modified form of SARS-CoV-2’s spike protein compared to the existing vaccine. It incorporates two key sections of the spike protein, allowing for a smaller dose. This streamlined approach proves beneficial for a combined vaccine and potentially extends its shelf life. The influenza component leverages the same mRNA technology as the existing COVID-19 vaccine but targets influenza proteins in the three dominant strains from the past season: H1N1 and H3N2 from the influenza A group, and an influenza B strain.

A study involving over 8,000 adults aged 50 and older saw approximately half receive the combination vaccine. The other half, serving as a control group, received separate shots: Moderna’s vaccine targeting the , and a flu shot (either Fluarix for those 50 to 64 years old, or Fluzone HD for those 65 and older).

In the younger cohort, the combined vaccine generated roughly 20% to 40% higher antibody levels against the influenza strains and 30% higher levels against XBB.1.5 compared to the control group. Among older participants, antibody levels were 6% to 15% higher against the flu strains and 64% higher against XBB.1.5 compared to the older control group.

“The primary benefit of a single shot is that individuals only require one injection,” explains Dr. Jacqueline Miller, senior vice president and head of development in infectious diseases at Moderna. She highlights a public health advantage as well, noting that U.S. vaccination rates for both diseases are relatively low. “By administering both vaccines together, we might see an increase in vaccination compliance rates, particularly among high-risk populations.”

Moderna is continuing to investigate both the COVID-19 vaccine and the flu shot utilized in the combined shot as separate vaccines. This data will support the U.S. Food and Drug Administration (FDA) in its review of the company’s application for approval of the combination shot, potentially arriving by the end of the year. The specific strains targeted in the shot will be tailored to the circulating viral strains at the time. (The company also submitted a request to the FDA on June 7th to update its COVID-19 vaccine to target the JN.1 variant.)

The combined vaccine is likely to be unavailable in time for this fall’s flu and COVID-19 season. However, in future years, a two-in-one vaccine could potentially boost vaccination rates, leading to reduced hospitalization rates for both diseases.