Building on the success of messenger RNA (mRNA) technology used to develop a vaccine against the COVID-19 virus, a novel quadrivalent mRNA-1010 vaccine for influenza was developed. The vaccine appears promising according to early results from the phase 1 study, according to a press release from the vaccine’s manufacturer. 

The quadrivalent mRNA-1010 vaccine boosted hemagglutination inhibition assay genomic mean titers against all four of the targeted influenza strains 29 days after vaccination. During the study, the vaccine was evaluated in three doses, ranging from 50 µg to 200 µg in adults between 18 and 49 and those older than 50. 

At day 29, younger patients given the 50 µg dose had geometric mean titers (GMT) against influenza A of 583 for H1N1 and 530 for H3N2. The GMT against influenza B strains were 467 for B/Yamagata and 261 for B/Victoria. The geometric mean fold-rises (GMFR) above baseline for influenza A strains were 10-fold for H1N1 and 8-fold for H3N2. For Influenza B strains, the GMFR was 3-fold for B/Yamagata and 2-fold for B/Victoria, with the researchers observing minimal dose response between the three dose levels. These findings could mean the possibility of lower doses in the future.

For the patients aged 50 and older, the 50 µg dose resulted in a GMT against influenza A strains of 310 for H1N1 and 263 for H3N2. The GMT against influenza B strains were 305 for B/Yamagata and 215 for B/Victoria. The GMFR for influenza A strains were around 6-fold for H1N1 and H3N2. For influenza B strains, the GMFR was around 3-fold for B/Yamagata and 2-fold for B/Victoria. Like the younger patients, a minimal dose response was observed between the three doses. 

Stéphane Bancel, chief executive officer of Moderna, said in the release that the goal of the program is to protect patients from the potentially dangerous effects of the flu “with an annual pan-respiratory single-dose booster vaccine that is adapted to the circulating strains of SARS-CoV-2, seasonal influenza, and [respiratory syncytial virus].”

“The positive interim results from our phase 1 quadrivalent flu vaccine candidate, mRNA-1010, are an important milestone toward achieving that goal,” Bancel said in the release. “It is encouraging to see that participants in the study who received the 50 µg dose, including older adults, achieving robust increases in geometric mean antibody titers against H1N1 and H3N2, the strains responsible for the vast majority of morbidity and mortality in this age group.” 

The phase 1 trial showed no significant safety risks through day 29. However, the release noted adverse events were more common in younger adults and those given higher doses. The most common adverse reactions included pain and axillary swelling/tenderness. The most common systemic adverse reactions included fatigue, arthralgia, myalgia, and headache. 

A phase 2 trial is also fully enrolled, with work underway for a phase 3 study. The phase 2 study includes a lower 25 µg dose in addition to 50 µg and 100 µg doses. An already-approved vaccine will serve as the comparator arm.An interim analysis of the trial is expected early next year.