A norovirus outbreak affected 102 passengers and 23 crew members aboard the Ruby Princess cruise ship before it docked at Pier 35S in San Francisco on Thursday morning, July 2, 2026.
The Centers for Disease Control and Prevention (CDC) reported that the illness struck nearly 5% of the 3,032 passengers and 1,144 crew members on board.
Outbreak Details
The vessel was concluding a 20-day round-trip journey to Canada and Alaska, which began on June 12. Representatives first reported the outbreak on June 28.
According to the CDC Vessel Sanitation Program, an outbreak is defined when 3% or more of passengers report symptoms.
This incident marks the third norovirus outbreak to affect a Princess Cruises watercraft this year, among six other recorded outbreaks across the cruise industry in 2026.
The highly contagious gastrointestinal virus causes vomiting and diarrhea, spreading through contaminated food, water, surfaces, or hand-to-mouth contact.
Health officials noted that wastewater data from mid-June showed high levels of norovirus circulating in Bay Area cities like Palo Alto and San Jose, though San Francisco is currently experiencing low levels.
Sanitation Response
The vessel implemented enhanced sanitation protocols during the voyage to isolate the sickened individuals and reduce active cases.
Port officials confirmed that the ship underwent comprehensive disinfecting before boarding new passengers for its next scheduled departure to Ketchikan, Alaska.
A spokesperson for Princess Cruises said that a limited number of guests reported mild gastrointestinal illness during the Ruby Princess voyage that left San Francisco on June 12.
The cruise line added that its crew implemented enhanced sanitation protocols and that cases have since decreased before the ship docked for further cleaning.
The spokesperson wrote that the ship was undergoing comprehensive cleaning and disinfection prior to departing in the afternoon at 4 p.
m.
Local authorities monitored the response at the terminal to ensure compliance with federal public health guidelines.
Port of San Francisco spokesperson Eric Young wrote that as the landlord for cruise terminal facilities, the Port’s role is to ensure that tenants follow required notification procedures with the appropriate public health authorities.
He verified that the deep-cleaning procedures were executed in alignment with standard sanitation guidelines.
