5% of Cruise Ship Passengers Diagnosed with Norovirus

The U.S. Centers for Disease Control and Prevention's (CDC) Vessel Sanitation Program (VSP) reports on various norovirus outbreaks onboard cruise ships.

According to the CDC's recent report, the Serenade of the Seas's current voyage (September 19, 2025–October 2, 2025), about 5% of passengers (94 of 1,874) experienced diarrhea and vomiting related to norovirus infections while traveling from San Diego to Miami.

The CDC reported on September 30, 2025, that, in response to the outbreak, Royal Caribbean International and the ship's crew implemented several measures, including enhanced cleaning and disinfection procedures, as outlined in their outbreak prevention and response plan.

The CDC wrote that norovirus is often a cause of GI illness outbreaks on cruise ships, but we don't always know the cause of the outbreak when we begin an investigation. Identifying the agent that caused an outbreak can take time.

So far in 2025, the VSP has identified approximately 19 cruise ship outbreaks, 15 of which were caused by norovirus.

The VSP reported 15 norovirus outbreaks aboard cruise ships in 2024.

While there are no approved norovirus vaccines available in 2025, a recent study showed that an oral vaccine candidate triggers antibodies that can neutralise a wide range of norovirus strains. It may also reduce the amount of virus that infected people shed, raising hopes that a broadly protective vaccine may be within reach.