An mRNA vaccine has received approval from the U.S. Food and Drug Administration (FDA) in the past week for seasonal influenza. mFlusiva is a single-dose vaccine that uses the same technology used to create COVID-19 vaccines. After the Phase 3 trial that involved over 40,000 participants in 11 countries, mFlusiva has demonstrated it is substantially more effective than existing flu shots. A single 0.38-millilitre intramuscular injection, when given to adults 65 years or older, proved to produce a 27.4% greater immune response. Common side effects included pain at the injection site and in muscles and bones, fatigue, headaches, chills, in some cases fevers, and in other cases nausea and vomiting. In other words, all the common side effects that almost every medication reports as contraindications.
Moderna and Pfizer are the two pharmaceutical companies that went all in on mRNA technology to develop COVID-19 vaccines. Their vaccines proved effective in preventing millions of deaths during the multi-year pandemic crisis. Since then, mRNA research has continued with vaccines produced to address new COVID variants and RSV, or respiratory syncytial virus, the latter a contagious virus that can be dangerous to the young and those over the age of 60 or suffering from complex medical conditions.
How mRNA Vaccines Differ
Since 2012, I have written about the promise of using mRNA to fight diseases and cancer. mRNA is DNA’s letter carrier. DNA writes instructions to cells to manufacture proteins and other essential chemicals necessary for cell survival. mRNA delivers the letters within the cell, which then opens them and carries out what DNA has written. Since the early 2000s, researchers have been experimenting with this natural mechanism of cellular biology to see if it could be “weaponized” to attack diseases. The COVID-19 vaccines developed by Moderna and Pfizer were the first successes. Where traditional vaccines could take between 18 months and three years to develop, the urgency of the spreading COVID-19 pandemic made mRNA an attractive option.
Just how fast can mRNA solutions be developed when compared to conventional vaccines? Influenza vaccine development and production today is state-of-the-art. Fastest to market, influenza vaccines get produced in six months.
What’s involved? Chicken eggs play a big part. Living influenza virus strains are injected into fertilized eggs to produce the product. If the wrong virus strains are selected, it can produce an ineffective vaccine for the coming flu season.
In comparison, mRNA vaccines are produced by synthesizing mRNA coding instructions contained within lipid nanoparticles, which are then injected to deliver instructions to cells responsible for our natural immune response system to recognize the virus and produce antibodies to attack it. Instead of six months, mRNA vaccines can be produced in 6 to 8 weeks.
Moderna is first to market with mFlusiva.
Why an mRNA Vaccine for Influenza is Significant
The World Health Organization (WHO) reports that seasonal influenza infections affect more than 1 billion annually. Of these, a small percentage are severely infected, requiring hospitalization, approximately 3 to5 million. Of these, up to 700,000 die from respiratory and cardiovascular complications.
In 2022, 194 WHO member states reported large-scale administration of 450 million influenza vaccinations. In 2023, of these countries, only 33 saw vaccine uptake of 15.9 per 100 people, showing the general lack of enthusiasm on the part of the general public to get jabbed. Yet flu vaccines are very effective in protecting the public from infections.
Egg-based vaccines, when the right virus strains get picked, can reduce the likelihood of getting the flu by 40 to 60%, and reduce hospitalizations from complications even more dramatically.
mRNA Research in the U.S. Threatened
When Robert F. Kennedy Jr. made the decision in 2025 to stop investing in mRNA research, it had negative implications for Americans and the health of the rest of us. Eliminating the US$ 500 million for almost all mRNA research meant abandoning a validated technology that had proven itself in combatting COVID-19. Twenty-two mRNA research projects were cut.
This happened despite a U.S. Centers for Disease Control study of the pandemic response that concluded mRNA vaccines reduced the potential for American hospitalizations and deaths from the virus by 90%.
RFK Jr’s decision was based on his anti-vaccine prejudices. He exploited the imperfect results being reported about mRNA vaccines, such as identified side effects:
- Rare reports of myocarditis and pericarditis, rare inflammations of the heart muscle and pericardial sack.
- Rare reports of febrile seizures occurring in young children.
- More common contraindications, including pain, fatigue, headaches, chills, fever, local swelling at the vaccination site, and occasional swelling in lymph nodes.
- Rare reporting of anaphylaxis (acute allergic reactions).
How different were these contraindications from what gets reported for most vaccines? Only a few.
RFK Jr. also noted that mRNA COVID-19 vaccines provided only short-duration immunization protection. Why was this? With new strains of COVID-19 cropping up, the latest mRNA vaccines became less potent over time. This led to a race between the virus and pharmaceutical companies to formulate mRNA vaccines to combat new variations.
For a time early in the pandemic, it meant revaccination often every six months. Today, COVID-19 has become endemic, meaning it continues to circulate.
New mRNA vaccine boosters, however, are more often being administered annually, in a similar fashion to the annual seasonal flu shot.
mRNA Research Defunding Consequences
Fortunately, the defunding decision did not stop all mRNA research in the U.S. mRNA vaccine research has continued to provide treatment for other pathogens, including virus-associated cancers. Nor has the funding cancellation affected mRNA vaccine production in the U.S.
It did cause the abandonment of several university and biotechnology-based research projects. In some cases, research and manufacturing of mRNA vaccines moved offshore. For example, Moderna established new facilities in Quebec and Ontario.
Fortunately, the new mFlusiva influenza vaccine is being produced in Massachusetts. mFlusiva is currently being reviewed by Health Canada, the European Union and Australia. It likely will be produced in the company’s Canadian facilities once a notice of compliance is issued for the upcoming seasonal vaccination period.
