Pull to refresh
Logo
Moderna's norovirus vaccine misses an early-success mark in Phase 3

Moderna's norovirus vaccine misses an early-success mark in Phase 3

New Capabilities

The mRNA maker's stomach-bug shot fell short of an interim bar and will add patients rather than stop the trial.

Today: Vaccine misses the interim success bar

Overview

Norovirus makes about 20 million Americans sick each year, and no vaccine has ever been approved to stop it. Moderna's shot is the furthest along. On July 31, 2026, the company said that shot fell short of the bar for early success in its big trial.

Moderna is not quitting. It will enroll another group of patients and keep the study going. The result delays, but does not kill, the chance at a first-of-its-kind vaccine against the stomach bug.

Why it matters

No vaccine exists for norovirus, the top cause of stomach flu. Moderna's shot is furthest along, and this stumble delays the first one.

Questions about this story

No questions yet — be the first to ask.

Key Indicators

0
Approved norovirus vaccines
No shot against norovirus has ever been licensed anywhere.
~38,000
Trial participants enrolled
The NOVA 301 Phase 3 study stays blinded as Moderna adds a cohort.
~900
US norovirus deaths per year
Most are adults over 65, the group the trial targets most.
$145M
Q2 2026 revenue
Beat the roughly $103 million analysts expected, on COVID sales.
~6%
Share drop on the news
The vaccine miss outweighed the revenue beat for investors.

Voices

Curated perspectives — historical figures and your fellow readers.

Ever wondered what historical figures would say about today's headlines?

Sign up to generate historical perspectives on this story.

Play

Exploring all sides of a story is often best achieved with Play.

Log in to play. Track your picks, climb the leaderboards. Log in Sign Up
Predict 4 ways this could play out. Contrarian picks score more — points lock when the scenario resolves. Log in to play
Higher or Lower Two numbers from this story. Guess which is bigger. 5 rounds to set a streak. Log in to play
Timeline Five events from this story — drag them oldest to newest. Log in to play
Connections Sixteen names from the news. Find the four hidden groups of four. Log in to play

People Involved

Organizations Involved

Timeline

August 2024 July 2026

6 events Latest: Today
Tap a bar to jump to that date
  1. Vaccine misses the interim success bar

    Today Clinical Trial

    In its Q2 report, Moderna said mRNA-1403 fell short of the statistical threshold for early success. It will add a patient group and continue rather than stop.

  2. Trial adds a second northern winter

    Clinical Trial

    Unable to catch enough natural infections, Moderna extended the study to a second Northern Hemisphere season to gather more cases.

  3. FDA lifts the hold

    Regulatory

    After review, the agency cleared the trial to resume enrollment and dosing.

  4. FDA pauses the trial over a nerve-disorder case

    Regulatory

    The FDA placed the study on clinical hold after one participant reported Guillain-Barré syndrome, a rare condition affecting the nerves.

  5. Moderna doses first patient in Phase 3

    Clinical Trial

    Moderna began its pivotal NOVA 301 study of mRNA-1403, aiming to enroll roughly 25,000 people, most of them over 60.

  6. Rival HilleVax drops its norovirus program

    Industry

    HilleVax cut 40% of staff after its infant vaccine showed just 5% efficacy in a mid-stage trial. Its exit thinned the field chasing a first norovirus shot.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

August 2024

HilleVax abandons its norovirus vaccine (2024)

HilleVax's infant norovirus vaccine, HIL-214, showed just 5% efficacy in a trial of more than 2,800 babies. The company cut about 40% of staff and dropped the program. Its shares fell sharply.

Then

HilleVax pivoted away from its lead product and the infant norovirus effort ended.

Now

The failure narrowed the field and raised doubts about how easily norovirus immunity can be induced.

Why this matters now

It shows norovirus is a graveyard for vaccine candidates. Moderna's miss fits a pattern, not a one-off.

May 2023

RSV vaccines finally approved (2023)

After roughly 60 years of failures, including a 1960s trial that made children sicker, GSK and Pfizer won FDA approval for the first RSV vaccines for older adults. The breakthrough came once scientists learned to lock the virus protein into the right shape.

Then

Millions of older adults gained access to a shot against a common respiratory virus.

Now

It proved a decades-elusive vaccine can be cracked with the right science and persistence.

Why this matters now

RSV shows long-stalled vaccine targets do eventually fall. Moderna is betting norovirus is next, not hopeless.

December 2020

Moderna's COVID-19 vaccine authorized (2020)

Moderna's mRNA COVID-19 vaccine won emergency use authorization about 11 months after the virus was sequenced, with roughly 94% efficacy in its pivotal trial. It made Moderna a major vaccine maker overnight.

Then

The vaccine drove billions in sales and validated the mRNA platform at scale.

Now

It set expectations Moderna is now trying to meet in harder diseases with weaker or shorter immunity.

Why this matters now

COVID showed mRNA can move fast. Norovirus shows the platform still meets targets where immunity is short-lived and strains vary.

Sources

(7)