No vaccine has been approved to prevent respiratory syncytial virus (RSV), but there are more than 30 different RSV vaccine candidates in clinical trials, according to PATH, a global health organization. Research from the Centers for Disease Control and Prevention (CDC) estimate that between 60,000 and 160,000 adults 65 and older are hospitalized each year with RSV, and 6,000 to 10,000 older adults die because of it.

RSV is very contagious, and for that reason most children have had the virus by their second birthday, according to the CDC. One to two out of every 100 children younger than 6 months of age with an RSV infection may need to be hospitalized. The virus is particularly dangerous to infants under 6 months and children under 2 with a heart condition or asthma.

The global market for RSV vaccines could be worth up to $10 billion by 2032, according to Bloomberg Intelligence. Three key pharmaceutical companies in the race to have the first Food and Drug Administration (FDA)-approved RSV vaccine include: Pfizer (PFE 0.66%), GSK (GSK -0.07%) and Moderna (MRNA 1.58%). The first two already are awaiting approval from the FDA for their vaccines after getting positive responses from FDA advisory panels.

Here's what getting an approved RSV vaccine would mean for each company.

Why it's important to Pfizer 

Pfzier's RSV vaccine, RSVpreF, got seven votes for and four against from the FDA advisory committee for both its vaccine's safety and effectiveness. The single-dose shot was shown to be 85.7% effective in preventing adults 60 and older from getting the virus, according to Pfizer. 

The company said it expects to hear the FDA's decision by the therapy's Prescription Drug User Fee Act (PDUFA) date in May.

The company could definitely use a shot in the arm from RSV revenue. Its shares are down more than 22% so far this year thanks to reduced 2023 guidance and looming patent cliffs for some of its top drugs, led by breast cancer blockbuster Ibrance, which brought in $5 billion last year but is expected to lose exclusivity in 2024 .

The potential loss of revenue from three key oncology drugs is a big reason why the company is spending $43 billion to purchase oncology company Seagen (NASDAQ: SGEN) and its deep pipeline.

The company had a strong 2022, with revenue of $100.3 billion, up 23%, and earnings per share (EPS) of $5.47, up 42%. However, those numbers were propped up a bit by sales of Pfizer's COVID-19 vaccine Comirnaty and its COVID-19 therapy Paxlovid. This year the company's guidance shows it expects revenue of $67 billion to $71 billion, down 33% to 29%, and adjusted EPS of $3.25 to $3.45, down 51% to 48%.

Why it's important to GSK

GSK's RSV vaccine candidate, RSVPreF3 OA, may be the early leader based on the FDA's advisory committee's vote, which was 10-2 for the vaccine's safety and a 12-0 vote on its effectiveness.

According to GSK, the vaccine was found to be 94.1% effective in preventing severe lower respiratory tract disease, 93.8% in patients 70-79, and 94.6% effective for adults with underlying conditions that could exacerbate RSV.

The company's financial picture is less reliant on its COVID-19 vaccine, Xevudy, than the other two companies are with theirs. In the fourth quarter GSK reported revenue of $11.6 billion, up 11% year over year, and yearly revenue of $36.3 billion, up 13%. The company's yearly EPS was $1.33, up 18%, and quarterly EPS was $0.43.

The company's pipeline includes 69 programs, with a focus on vaccines and specialty medicines. 

Why it is important to Moderna

Moderna is behind Pfizer and GSK in the race for an RSV vaccine, but not by much. The company, which used its mRNA technology to speedily develop its COVID-19 vaccine, has used the same technology to bring its RSV vaccine, mRNA-1345, from a Phase 1 trial to Phase 3 in 13 months.

The therapy received Breakthrough Therapy Designation from the FDA and, according to Moderna, was 83.7% effective in preventing RSV in older adults. The company said it plans to submit its Biologics License Application (BLA) for mRNA-1345 in the first half of the year. In the meantime, the company also has a pediatric Phase 1 trial for the therapy that is fully enrolled.

Moderna, like Pfizer, also had record revenue in 2022, but is facing the likelihood of lower revenue this year as sales from its COVID-19 vaccine Spikevax decline. The company reported 2022 revenue of $19.3 billion, up 4%, but its fourth-quarter numbers showed what's likely ahead with a drop of 29.4% year over year to $5.1 billion. Yearly EPS was $20.12, down from $28.29 in 2021, while quarterly EPS was $3.61, down from $11.29 in the same period last year.

Moderna's only commercial product is Spikevax, but its pipeline is booming with 48 programs, including four in Phase 3: the mRNA-1345, a COVID booster, flu vaccine mRNA-1010, and its Cytomegalovirus (CMV) vaccine mRNA-1647. 

Still, the company is more reliant than the other two on getting its RSV vaccine approved, as it has no other marketed therapy yet besides Spikevax.

Making a choice

Of the three stocks, GSK is in the strongest position, whether or not its RSV vaccine is approved. The company isn't facing big patent cliffs like Pfizer is, and it has a lot more balanced revenue coming in than Moderna. GSK's vaccine, currently in trials, appears to be the most effective of the three, but at this point there's been no determination of which vaccine will have the longest effectiveness, and that's important as well.