The Pfizer-BioNTech and Moderna COVID-19 vaccines changed the game forever through their use of messenger RNA (mRNA), a molecule found in every cell in the human body. Researchers are exploring the potential of mRNA-based vaccines not only to fight the flu but also to prevent a swath of illnesses, from HIV to liver disease. “The development and implementation of the mRNA vaccines for COVID-19 is the culmination of 40 years of research from thousands of labs around the world; it’s one of the most impressive human endeavors ever,” says Jeff Coller, PhD, Bloomberg distinguished professor of RNA biology and therapeutics at the biochemistry, cellular, and molecular biology graduate program at the Johns Hopkins University School of Medicine in Baltimore. “Now that we have that technology — we know that the mRNA is safe and efficacious — it’s just going to start a whole new movement of mRNA-based vaccines and therapies,” Dr. Coller says. Researchers are studying ways that mRNA medicines could carry instructions to a patient’s cells to produce proteins to prevent, treat, or even cure a variety of diseases that we’ve never been able to tackle before, says Coller. Moderna is current developing 24 mRNA-based vaccines or therapies. The flu is an important target of these efforts. Current flu vaccines reduce the risk of illness by 40 to 60 percent during seasons when the shot is well matched to circulating flu viruses, according to the Centers for Disease Control and Prevention (CDC). Compare that to the Pfizer-BioNTech and Moderna mRNA COVID-19 vaccines, which were shown to be 95 percent and 94 percent effective at preventing symptomatic infection, respectively. (Though this data precedes the spread of mutations like the Delta variant). “What we’ve seen in the efficacy of the mRNAs for COVID-19 is outstanding,” says Coller. “If an mRNA-based flu vaccine elicits the same type of strong immune response, that on its own might give it a boost in efficacy over traditional vaccines.”
How mRNA Vaccines Work
The Pfizer and Moderna COVID-19 vaccines are the first mRNA immunizations authorized for use in humans. As the CDC explains, these mRNA vaccines give instructions to our cells to make a harmless piece of what is called a spike protein, which is a replica of the spike protein on the surface of the coronavirus that causes COVID-19. The body recognizes the spike protein as foreign, triggering an immune response and the creation of antibodies, the protective proteins that remain in the bloodstream ready to fight off the actual coronavirus should a person become infected. RELATED: 7 Biggest COVID-19 Vaccine Myths
An mRNA Flu Vaccine Could Have Several Advantages
One potential advantage of mRNA vaccines over the existing kinds is that they are a lot quicker to manufacture. The process of creating a traditional vaccine begins each year when the World Health Organization (WHO) determines which viruses will be included in the flu vaccine for the coming season, usually basing choices for the Northern Hemisphere on viruses that were circulating in the Southern Hemisphere earlier in the flu season. These viruses are sent to pharmaceutical companies, which use them to manufacture vaccines. “The production is quite difficult,” says Coller. The most common flu vaccine is egg-based, a process that has been used for more than 70 years. Scientists inject a live virus into a fertilized hen’s egg and let the virus replicate. The replicated viruses have to be collected, purified, and then killed (inactivated) before the production process can start. All told, creating a traditional flu vaccine can take five to seven months, according to a paper published in ACS Central Science journal. In contrast, “the beauty of the mRNA vaccines is they are really easy to make,” says Coller. Scientists don’t have to use live cells in a lab because mRNA vaccines are made synthetically using the sequence of the virus. “Once you have that sequence, you can make an mRNA vaccine to fight the virus in a couple weeks,” he adds. The ability to produce an mRNA flu vaccine in weeks rather than months would mean less time for the circulating flu virus to mutate. Flu viruses can mutate even in the replication phase of the egg-based vaccine manufacturing process, according to the ACS Central Science paper, which wouldn’t be a concern with mRNA vaccines. Virus mutations, however they happen, reduce the overall effectiveness of the flu shot. RELATED: 7 Flu Shot Myths You Should Stop Believing
Rescue Vaccines Mid-Flu Season May Be Possible With mRNA
Sometimes the WHO’s educated guess on what strains of the flu will be circulating misses the mark, which makes the vaccine less protective. The mRNA vaccines may have a work-around for that possibility, too. Because of the speed in which the vaccines can be sequenced and manufactured, it may be possible to create a rescue vaccine mid-flu season to fight an outbreak caused by a strain that wasn’t addressed in the original vaccine, according to a release by Pfizer.
Could a One-and-Done Shot Protect Us From COVID-19 and the Flu Someday?
“We already do that today,” Coller points out about the potential of a single injection that can protect against multiple diseases. “For example, kids get mumps, measles, and rubella vaccine all in one shot, and it works just fine. It wouldn’t surprise me if we see a cocktail of a coronavirus and influenza vaccine in one shot.” In an interview on April 14, Moderna CEO Stephane Bancel said that the company is developing a flu vaccine that it plans to combine with a COVID-19 vaccine “so that you only have to get one boost” a year to protect you from the circulating coronavirus and flu strains.
Trials Are Happening Now
An mRNA flu shot may be available sooner than you think, in part because Pfizer and Moderna were already working on a flu-based mRNA vaccine before the pandemic, says Coller. In 2018, Pfizer and BioNTech announced their partnership in developing an mRNA vaccine for the flu. On June 22, 2021, the pharmaceutical companies Sanofi and Translate Bio announced the start of a phase 1 clinical trial of an mRNA flu vaccine. They anticipate having interim data by the end of the year, making it highly unlikely that any resulting mRNA flu shot would be available this flu season. A few weeks later, on July 7, Moderna announced that the first participants were dosed in its phase 1/2 study of an mRNA flu vaccine.
