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Moderna wins FDA approval for RSV vaccine

The Food and Drug Administration on Friday approved a third vaccine for respiratory syncytial virus, clearing a shot from biotechnology company Moderna one year after granting a green light to vaccines from GSK and Pfizer.

The vaccine, dubbed mResvia, is for the prevention of disease caused by respiratory syncytial virus, or RSV, in adults 60 years of age and older. Experts from the Centers for Disease Control and Prevention are expected to meet next month to provide recommendations on the shot’s use. Moderna had said it expects the vaccine to be available in time for the fall immunization season in the U.S.

RSV can cause severe disease in infants, the elderly and immunocompromised individuals, in some cases leading to death. The virus typically circulates during the fall and winter in the Northern Hemisphere, similar to the seasonal pattern for influenza and COVID-19.

“RSV is finally being appreciated as an adult disease with a considerable morbidity, mortality, and impact on hospital capacity,” said Amesh Adalja, an assistant professor at the Johns Hopkins Bloomberg School of Public Health and an infectious disease physician, in a May interview. “The virus is finally being taken seriously, hopefully, more vaccine options will increase uptake.”

Scientists for decades struggled to develop a safe and effective vaccine for RSV. Their efforts were unsuccessful until a breakthrough in 2013 paved the way for development of the current crop of vaccines that are now reaching the market.

British drugmaker GSK was the first to gain approval in the U.S. with its vaccine Arexvy cleared for use in older adults last year. Pfizer followed weeks after with its shot Abrysvo. Later last summer, the FDA granted Abrysvo an additional approval for maternal use

Demand has been high. In the first year it was approved, Arexvy brought in 1.2 billion pounds, or about $1.5 billion, for GSK, growing the company’s vaccine business. Pfizer’s shot has also done well, although sales haven’t been as strong as GSK’s. The company reported $515 million in Abrysvo sales in 2023.

Moderna plans to compete. It will have to, as declining sales of its popular COVID vaccine have put pressure on the company to deliver growth from other products.

Like its COVID shot, mResvia is built around messenger RNA. It trains the body to recognize the “prefusion” F protein of RSV, similar to Pfizer’s and GSK’s vaccines.

Moderna points to mResvia’s preparation and delivery as advantages versus the competition. On a recent earnings call, Moderna CEO Stéphane Bancel said the shot could ease “personnel burden on pharmacies” with a prefilled syringe formulation versus its competitors’ more-complex-to-administer shots.

“Our pre-filled syringe presentation is ready to use straight out of the box,” said Bancel on the May 2 call.

The CDC meeting in June will be important, as contracts with pharmacies are likely to be finalized after the agency’s recommendations. Due to RSV’s seasonal pattern, the late summer-to-fall period is when immunization campaigns are prepared.

This was borne out in the first quarter this year, as Arexvy and Abrysvo sales declined from the three months between October and December.

“It very much appears like the RSV vaccination market is following a seasonal trend, so you expect the dynamics in Q4 versus Q1 to be different,” said Pfizer’s Chief U.S. Commercial Officer Aamir Malik on a first quarter earnings call.

Moderna expects the total RSV vaccine market to grow to between $6 billion and $8 billion in annual sales. There is “debate” on how much market share Moderna could gain considering it’s third to market, Jefferies analyst Michael Yee wrote in a recent note to clients

“I think [Moderna] may be a victim of the fact that it is later to the market than its competitors, as well as the fact that there is an irrational opposition to mRNA vaccines,” said Adalja.

Dan Barouch, an immunologist and professor of medicine at Harvard Medical School, has the opposite view. He thinks Moderna’s shot will perform well given the demand seen with other RSV vaccines, and doesn’t expect skepticism over COVID shots to affect uptake.

Moderna said it expects net sales of about $4 billion in 2024 between its COVID and RSV vaccines, but did not give specific guidance for mResvia.

“If its efficacy or durability is shown or suggested to be better than Pfizer and GSK’s versions, it may have an opening,” Adalja said.

In testing, Moderna’s shot proved about 84% effective against RSV-related disease with two or more symptoms, comparable to GSK’s shot. Pfizer’s Abrysvo appeared slightly less effective in its studies, but the results are not directly comparable.

When measured throughout a second RSV season, efficacy for each of the three shots wanes with time. mRESVIA’s effectiveness fell to about 63% after 8.6 months, raising questions over the durability of the vaccine’s protection versus its two rivals.

In testing, all three RSV vaccines proved to be generally safe, most commonly causing side effects like fatigue, headache and injection site pain.

Recently, CDC experts have examined data suggesting a possible association between the shots and Guillain-Barré syndrome, an autoimmune disorder that in rare cases can lead to paralysis. One case of GBS was reported by GSK in clinical testing, while Pfizer reported two. Moderna has not disclosed any cases from its trials.

At a March meeting, the advisers concluded Arexvy’s and Abrysvo’s benefits outweighed any risk and, while they noted data suggesting a slight increase in GBS risk, couldn’t confirm a direct link.

Although the initial focus of vaccination has been on older adults, RSV vaccine companies are working to determine who else may be eligible for immunization. Moderna is running other trials evaluating mResvia in high-risk adults 18 and older, while Pfizer recently read out results from a similar test of its own shot. GSK, meanwhile, is awaiting regulatory approval of Arexvy for adults between the ages of 50 and 59.