The flu statistics from Moderna provide a clear lesson: mRNA isn't magical.

Moderna announced ambitions to leverage its newly proven mRNA platform to successfully revolutionize how the world prevents humanity's most persistent viral adversaries last autumn, when their Covid-19 vaccine reached the finish line.

In addition to their current vaccination efforts, officials revealed new ones for flu, where vaccines have consistently failed, and HIV, which has defied every vaccine effort for over four decades. In the case of flu, the other mRNA vaccine businesses — BioNTech (with Pfizer), Translate Bio (with Sanofi), and CureVac (with GSK) — all had similar goals, aiming for doses that were as effective as 80%.

Those high aspirations, however, were dashed on Friday morning. Moderna was the first business to make data on an mRNA flu candidate public, and it looked good.

The business demonstrated that the vaccine may successfully produce antibodies against the four flu virus families that are currently targeted by killed virus and protein-based vaccines. Experts say there was no evidence in the early data that it was any better in inducing such antibodies.

In effect, the corporation re-created the same old photo in a new outfit.

"It's exactly as excellent as what we have currently," said Peter Palese of the Icahn School of Medicine, who researches flu and flu vaccinations. "However, I don't believe anything we've seen thus far is breaking new ground or introducing a wholly new technology."

"mRNA is not a silver bullet," as his colleague Florian Krammer put it on Twitter.

An mRNA version of the present flu injections might still be effective and offer a few benefits, but they also have their own set of flaws that are typically overlooked. The shot's reactogenicity, or potential to induce substantial headaches, fever, and other unpleasant side effects in the days following inoculation, is one of them.

According to Moderna's statistics, its flu shot produced more adverse responses than protein-based or live viral vaccines, just like its Covid-19 vaccine. Analysts on a conference call noted that this might stymie Moderna's larger goal of developing a single seasonal injection that mixes flu, RSV, and Covid-19 vaccines — a vision that can only be realized with mRNA.

SVB Leerink's Mani Foroohar wondered how reactogenic the flu and coronavirus shots would be coupled if they both caused such adverse effects on their own.

However, a single mRNA flu injection, according to Palese, might raise safety concerns. The adjuvant function of the lipid nanoparticles that deliver mRNA to cells is to stimulate the innate immune system. This improves people's safety, but if done yearly, it might have long-term consequences.

The flu vaccinations given to the majority of patients nowadays are not adjuvanted. Only people over the age of 65 are usually given an adjuvanted flu vaccination like Fluzone.

"I believe there has been a preliminary reluctance to use adjuvants for influenza vaccinations since one does not want to administer an adjuvant every year, for the rest of one's life," he added.

Moderna executives warned against drawing broad comparisons between vaccinations before the findings of a head-to-head study were available. They also mentioned several additional places where scientists believe mRNA may be beneficial.

mRNA, for example, may be produced more quickly than traditional egg or cell-grown flu vaccines. In theory, this would allow Moderna and other mRNA firms more time to ensure that the flu strains in the vaccine match the flu viruses circulating in the autumn, reducing an issue that may reduce the seasonal shot's effectiveness to as little as 19 percent in certain years.

How much they chip away will be determined by Moderna's ability to make the shot quickly. Palese believed the benefit would be considerable, but Moderna president Stephen Hoge stated that the business is already planning to produce an Omicron-specific model in 100 days. In February, officials, on the other hand, must choose strains.