Moderna Norovirus Vaccine Misses Phase 3 Interim: NOVA 301 Falls Short of Statistical Bar

Moderna’s norovirus vaccine candidate mRNA-1403 did not meet statistical criteria for early success at a Phase 3 interim analysis, the company disclosed in its Q2 2026 earnings report on July 31. The stock fell 5.4% to close at $54.82, down from $57.92 the prior session.

The Phase 3 NOVA 301 trial (NCT06592794) enrolled roughly 37,800 adults across 283 sites globally. It is an observer-blinded, placebo-controlled study testing mRNA-1403 against placebo for the prevention of moderate or severe acute gastroenteritis caused by norovirus. The trial remains blinded, and Moderna is preparing to enroll an additional cohort in an effort to accumulate more efficacy cases over a third winter season.

What went wrong

Moderna conducted the interim analysis after the trial’s second norovirus season. President Stephen Hoge told investors on a Friday morning call that the epidemiology of the primary endpoint cases came in slower than expected, partly because the first season saw an outbreak of different norovirus strains than the vaccine targets.

“We know we will need additional cases from a further cohort to strengthen that statistical analysis,” Hoge said, comparing the situation to seasonal flu vaccines that often require multi-season studies to accrue enough infections.

The company has not yet released the statistical analysis plan or specific efficacy numbers from the interim look. The trial is ongoing.

Why it matters

Norovirus is one of Moderna’s key pipeline programs beyond its COVID and flu franchises. There is no approved norovirus vaccine on the market, and the illness causes an estimated 200,000 deaths globally each year, mostly in developing countries and among older adults. A successful vaccine would have given Moderna a first-mover position in a new infectious disease category and diversified revenue away from its aging COVID franchise.

The miss adds pressure to a company already dealing with a difficult environment. Moderna has been scaling back vaccine investment amid growing anti-vaccine sentiment in the U.S. and at the Department of Health and Human Services. In Q2, the company also terminated an inhaled mRNA cystic fibrosis candidate (VX-522) developed with Vertex Pharmaceuticals due to tolerability issues.

The financial picture

Moderna reported Q2 revenue of $145 million, slightly above the $142 million from the same quarter in 2025, beating analyst consensus. Quarterly vaccine sales of $94 million topped the $74 million consensus estimate from William Blair, driven largely by international sales of Spikevax and mNexspike.

Net loss was $782 million, or $1.97 per share, an improvement from the $2.13 per share loss a year earlier. Cash and investments stood at $6.9 billion as of June 30, down from $7.5 billion at the end of March. The company lowered its 2026 R&D expense guidance to approximately $2.9 billion from $3.0 billion and improved its year-end cash projection to $4.7 to $5.2 billion.

Moderna reiterated its target of up to 10% revenue growth for 2026, counting on international vaccine contracts to offset declining U.S. sales.

What to watch next

The next near-term catalyst for Moderna is the August 5 PDUFA date for mFLUSIVA, its seasonal influenza vaccine candidate. An FDA advisory committee voted unanimously in favor of the vaccine in June. If approved, it would be Moderna’s fifth commercial product and the first mRNA flu shot on the U.S. market. Beyond flu, the company expects Phase 3 melanoma data for its personalized cancer vaccine intismeran (mRNA-4157, partnered with Merck) potentially in 2026, and registrational data for its propionic acidemia candidate mRNA-3927. For a deeper analysis of Moderna’s Q2 results and the mFLUSIVA thesis, see our full earnings analysis.