Moderna stock tumbled Wednesday after the company said its newly approved RSV vaccine was only about 50% effective after 18 months — paling in comparison to rivals from Pfizer and GSK.
Respiratory syncytial virus, or RSV, causes coldlike symptoms in most people. But it can be serious or deadly in newborns and older adults.
After 18 months, Moderna's RSV vaccine proved 49.9% to 50.3% effective against multiple symptoms of lower respiratory tract disease. In comparison, GSK said its vaccine, Arexvy, was 78.6% effective against severe RSV after two years. Similarly, Pfizer's Abrysvo was 77.8% effective midway through a second season on the market.
Moderna stock toppled 11% to 122.45 on today's stock market. Pfizer stock also fell more than 2% to 27.42, while GSK stock skidded 3.6% to 38.87.
Moderna Stock: Blockbuster Predictions
All three companies sell RSV vaccines for people age 60 and older.
Pfizer and GSK use older technology in their vaccines, while Moderna's is based on the same mRNA technology behind its Covid vaccine, Spikevax. Pfizer's Abrysvo is also approved for pregnant women, while GSK's Arexvy can be used in people age 50 to 59 who are at high risk of severe RSV.
Though Moderna is coming from behind, the company says mResvia could be a strong competitor. The RSV vaccine comes in a pre-filled syringe, which makes the process of vaccinating people easier. It will hit the market this fall, in timing with the second season for Arexvy and Abrysvo.
Last year, GSK's Arexvy brought in nearly $1.58 billion in sales, leading $890 million from Pfizer's Abrysvo. This year, they are expected to generate a respective $1.95 billion and $1.29 billion.
Moderna stock analysts predict $397 million in mResvia sales this year. In 2026, the RSV vaccine could become a blockbuster with $1.48 billion in sales, according to FactSet.
Waning Effectiveness
Notably, a Moderna spokeswoman said all three RSV vaccines lose effectiveness over time.
"As you know, immunity from RSV is not lifelong, and as with all currently licensed RSV vaccines, mResvia demonstrates waning (effectiveness) over time," she said in an email to Investor's Business Daily. "MResvia's strong clinical and safety profile will offer important protection to eligible populations who are at high risk for severe outcomes from RSV-related disease."
Moderna stock has a strong Relative Strength Rating of 92, according to IBD Digital. This puts the biotech stock in the top 8% of all stocks when it comes to 12-month performance. Shares fell below their 200-day moving average on Wednesday, MarketSurge shows.
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