Guidance for Cruise Ships on Management of Acute Respiratory Illness (ARI) due to Viral Infection

Outbreaks of influenza, COVID-19, respiratory syncytial virus (RSV), and other viral respiratory infections can occur at any time of the year among cruise ship passengers and crew members. Many cruise ship travelers are older adults or have underlying medical conditions that put them at increased risk of complications from these respiratory virus infections. Early detection, prevention, and control of such acute viral respiratory infections are important, not only to protect the health of passengers and crew members on cruise ships, but also to avoid spread of these viruses into communities.

Purpose

This document provides guidance for cruise ships originating from or stopping in the United States to help prevent, diagnose, and medically manage acute respiratory illness (ARI) caused by SARS-CoV-2 (the virus that causes COVID-19), influenza virus, or RSV. This guidance to cruise ship clinics will be updated as needed. CDC recognizes that cruise ships travel worldwide, necessitating awareness of, and responsiveness to, local jurisdictional requirements. Cruise ship management and medical staff need to be flexible in identifying and caring for people with ARI. The healthcare provider’s assessment of a patient’s clinical presentation and underlying risk factors is always an essential part of decisions about the need for further medical evaluation, testing, and treatment.

This document also provides guidance for preventing spread of ARI during and after a voyage, including personal protective measures for passengers and crew members and control of outbreaks.

Describing and Defining Passengers and Crew with Acute Viral Respiratory Illness (ARI)

Signs and symptoms of ARIs can include acute onset of some or all of the following:

• fever or feeling feverish
• cough
• runny nose
• nasal congestion
• sore throat
• shortness of breath
• difficulty breathing
• rigors
• chills
• muscle or body aches
• headache
• fatigue (tiredness)
• loss of taste or smell
• diarrhea
• vomiting

For cruise ship surveillance purposes, CDC defines ARI as an illness of presumed viral etiology with at least two of the following symptoms: fever/feverishness, cough, runny nose, nasal congestion, or sore throat and excluding:

• Confirmed acute respiratory infection diagnoses other than COVID-19 ^[1], influenza ^[2], or RSV ^[3] (e.g., Streptococcal pharyngitis, Epstein-Barr virus infection),*
• Diagnoses of bacterial pneumonia: either clinical or test-positive (e.g., by urine Legionella antigen, urine Streptococcus pneumoniae antigen), and
• Non-infectious conditions as determined by the ship’s physician (e.g., allergies)

Fever (a temperature of 100°F [37.8°C] or higher) will not always be present in people with influenza, COVID-19, or RSV. Cruise ship medical personnel should consider someone as having a fever if the sick person feels warm to the touch, gives a history of feeling feverish, or has an actual measured temperature of 100°F (37.8°C) or higher.

*Other respiratory viruses—for which point-of-care diagnostic tests are not available—may also cause ARI (e.g., rhinovirus, adenovirus, enterovirus, human parainfluenza viruses, human metapneumoviruses).

[1] Confirmed COVID-19 means laboratory confirmation for SARS-CoV-2, the virus that causes COVID-19, by viral test.

[2] Confirmed influenza means laboratory confirmation for influenza A or B by viral test.

[3] Confirmed RSV means laboratory confirmation for RSV by viral test.

Reducing the Spread of Viral Respiratory Infections

Commercial maritime travel is characterized by the movement of large numbers of people in enclosed and semi-enclosed settings. Like other close-contact environments, these settings can facilitate the transmission of respiratory viruses from person to person through droplets and small particles or potentially through contact with contaminated surfaces.

CDC recommends that efforts to reduce the spread of respiratory viruses on cruise ships focus on encouraging crew members and passengers:

• 6 months and older to get vaccinated annually for influenza
• 6 months and older to stay up to date with their COVID-19 vaccines
• who are 60 years and above to discuss and consider RSV vaccination with their healthcare provider
• To follow recommendations for babies and young children and if applicable, to receive monoclonal antibody products to prevent severe RSV
• To avoid contact with ill people prior to scheduled cruising
• To postpone travel if sick with an acute respiratory illness (passengers)
• To take steps to protect themselves and others while traveling
• To consider wearing a mask in crowded or poorly ventilated indoor areas.

Cruise ship management should include:

• Encouraging good respiratory hygiene and cough etiquette
• Early identification and isolation of crew members and passengers with ARI
• Use of antiviral medications for treatment of people with suspected or confirmed influenza or COVID-19 with severe or complicated illness, or at increased risk of severe illness or complications
• Use of antiviral chemoprophylaxis for post-exposure prophylaxis (PEP) or during influenza outbreaks, if indicated, for people at increased risk of complications

Vaccination of Crew and Passengers

All passengers and crew are also recommended to be up to date with all routine vaccines.

Influenza: CDC recommends that all people 6 months of age and older be vaccinated each year with the influenza vaccine. Crew members should be vaccinated yearly. Vaccination of passengers, especially those at high risk for influenza complications, is recommended at least 2 weeks before cruise ship travel, if influenza vaccine is available and the person has not already been vaccinated with the current year’s vaccine. For more information on influenza vaccine recommendations, see Seasonal Influenza Vaccination Resources for Health Professionals.

COVID-19: CDC recommends that all people 6 months of age and older be up to date with their COVID-19 vaccines. In addition to the protection COVID-19 vaccines provide to individual travelers in preventing severe illness or death from COVID-19, having a high proportion of travelers on board who are up to date with COVID-19 vaccines reduces the likelihood that cruise ships’ medical centers will be overwhelmed by cases of COVID-19. For more information on COVID-19 vaccine recommendations, see COVID-19 Vaccination Clinical and Professional Resources.

RSV: CDC recommends adult travelers ages 60 years and older discuss RSV vaccination with their healthcare provider prior to cruise travel. These new vaccines—which are the first ones licensed in the U.S. to protect against RSV—have been available since the fall of 2023. Babies and young children should follow recommendations and if applicable, receive monoclonal antibody products to prevent severe RSV. For more information, see For Healthcare Professionals: RSV (Respiratory Syncytial Virus).

Pre-embarkation COVID-19 Testing

To reduce the likelihood of onboard transmission of SARS-CoV-2, pre-embarkation testing is recommended for all passengers, including those on back-to-back sailings ^[4]. Completion of testing closer to the time of embarkation (within 1 to 2 days) maximizes the benefit of preventing introduction of infectious persons onboard. Ships that choose to use COVID-19 antigen tests should follow FDA guidance.

[4] Back-to-back sailing refers to passengers who stay on board for two or more voyages.

Viral ARI Screening Procedures for Embarking Passengers

Cruise ship operators should consider screening embarking passengers for viral ARI symptoms, a history of a positive COVID-19 viral test within the 10 days before embarkation, and a history of exposure to a person with COVID-19 within the 10 days before embarkation.

Cruise ship operators should consider performing viral testing (e.g., COVID-19, influenza, RSV) for passengers with ARI before they embark. Ships that choose to use COVID-19 antigen tests should follow FDA guidance.

Cruise ship operators should consider denying boarding for passengers who test positive for infectious viral etiologies during pre-embarkation screening, as well as those who tested positive for COVID-19 within 10 days before embarkation. If boarding is permitted, see guidance for isolation and other measures provided below.

If the cruise ship operator chooses to test for other infectious etiologies and testing identifies an alternate etiology (e.g., Legionella, Epstein-Barr virus, Streptococcal pharyngitis) through laboratory testing, routine infection control precautions specific to the diagnosis should be followed.

For asymptomatic passengers who have a known COVID-19 close-contact exposure within the 10 days before embarkation, considerations for allowing boarding can include:

• being up to date with COVID-19 vaccines,
• having a negative result on a COVID-19 viral test conducted on the day of boarding, or
• having documentation of recent recovery ^[5] from COVID-19

People who are up to date with COVID-19 vaccines are less likely to have severe outcomes if they develop COVID-19 after boarding. Testing is generally not recommended for asymptomatic people who recovered from COVID-19 in the past 30 days. If exposed passengers are allowed to board, see information below regarding recommendations for management onboard.

[5] Documentation of recent recovery from COVID-19 can include the following:

• Paper or electronic copies (including documentation of at-home antigen results) of their previous positive viral test result dated no less than 10 days and no more than 30 days before date of embarkation
• A positive test result dated less than 10 days before embarkation accompanied by a signed letter from a licensed healthcare provider indicating symptom onset more than 10 days before the voyage

Managing Cruise Travelers with ARI and Contacts while on Board

Travelers with ARI who board, as well as those who become sick with ARI onboard, should be identified and tested as soon as possible to minimize transmission of respiratory viruses. The table below provides disease-specific recommendations for persons on board with COVID-19, influenza, or RSV and those exposed (i.e., contacts).

^§ The day of last exposure to a case is counted as day 0. Additional testing prior to day 6 can identify new cases earlier. Cruise ship operators may consider this strategy in situations where exposures may have occurred in crowded settings, if unsure of the date of exposure, or if there is difficulty identifying index cases, as often occurs in the cruise ship environment.

^{^} Individual should properly wear a respirator or well-fitting mask at all times when outside of cabin indoors until 10 days after the last close contact with someone with COVID-19 (the date of last exposure to a case is considered day 0). During this time, these individuals should have in-cabin dining (with food trays placed and collected outside of cabins) and also wear a respirator or well-fitting mask inside their cabin if any other person (such as a crew cleaning staff) enters the cabin.

^† Contacts with high risk of influenza complications should be identified in order to offer post-exposure prophylaxis (PEP)

Crew members with ARI, even if mild, should take the following additional steps—regardless of their COVID-19, influenza, or RSV vaccination status:

• Notify their supervisors.
• Report to the medical center for evaluation and testing, if indicated, according to shipboard protocols.
• Continue to practice respiratory hygiene, cough etiquette, and hand hygiene after returning to work, because respiratory viruses may be shed after the isolation period ends.

Managing Passengers or Crew with ARI upon Disembarkation

Disembarking cruise ship passengers or crew members who have ARI should continue to take recommended precautions after disembarkation. If a passenger or crew member with viral ARI is taken to a healthcare facility off the ship, the facility should be informed before arrival. Medical transport providers should also be notified in advance.

Medical Evaluation and Management

Medical centers on cruise ships can vary widely depending on ship size, itinerary, length of cruise, and passenger demographics.

• Cruise ship medical centers are recommended to follow the operational guidelines published by the American College of Emergency Physicians (ACEP) as well as disease-specific clinical guidelines (see links provided at the bottom of this section).
• To reduce the spread and severity of ARI, cruise ship medical centers should carry a sufficient quantity of personal protective equipment (PPE), medical, and laboratory supplies:
  • PPE should include surgical masks and NIOSH Approved® N95® filtering facepiece respirators or higher, eye protection such as goggles or disposable face shields that cover the front and sides of the face, and disposable medical gloves and gowns.
  • Antiviral agents and other therapeutics for COVID-19, influenza, and RSV (if commercially available), and other antimicrobial medications
  • Antipyretics (e.g., acetaminophen and ibuprofen), oral and intravenous steroids, supplemental oxygen
  • Onboard capacity to conduct viral tests for SARS-CoV-2 and influenza, and RSV, as well as other infections that may be in the differential diagnosis (e.g., group A Streptococcus, Streptococcus pneumoniae, Legionella)
• Medical center staff should adhere to standard and transmission-based precautions when healthcare personnel are caring for patients with suspected or confirmed COVID-19, influenza, RSV, or other communicable diseases.

For more information, read updated resources for clinicians and guidance on the medical evaluation and management of people with COVID-19, influenza, or RSV are available on CDC’s websites.

Diagnostic Tests for Acute Viral Respiratory Illness (ARI)

Respiratory specimens for ARI testing should be collected immediately upon illness onset, with the understanding that repeat testing may be indicated based on the viral etiology or state of the COVID-19 pandemic. In general, molecular tests are recommended over antigen tests because of their greater sensitivity; multiplex assays are available that can detect SARS-CoV-2, influenza A and B, and RSV.

Healthcare providers should understand the advantages and limitations of rapid diagnostic tests, and proper interpretation of negative results of any antigen diagnostic tests. Rapid antigen diagnostic tests have a lower sensitivity compared with RT-PCR, and false negative results can occur frequently. In symptomatic persons, negative rapid antigen diagnostic test results do not exclude a diagnosis of COVID-19, influenza, or RSV; clinical diagnosis of these illnesses should be considered; however, positive test results are useful to establish a viral etiology and to provide evidence of infection in passengers and crew members aboard ships.

Respiratory and Hand Hygiene

People with ARI should be advised of the importance of covering coughs and sneezes and keeping hands clean because respiratory viruses may be shed after the isolation period ends.

Cruise operators should ensure passengers and crew have access to well-stocked hygiene stations with soap and water and/or hand sanitizer, tissues, paper towels, and trash receptacles.

Respirators or well-fitting masks should be readily available and symptomatic passengers and crew should be encouraged to use them if they have to be outside their cabins.

Passengers and crew members should be reminded to wash their hands often with soap and water, especially after coughing or sneezing. If soap and water are not available, they can use an alcohol-based hand sanitizer that contains at least 60% alcohol.

Used tissues should be disposed of immediately in a disposable container (e.g., plastic bag) or a washable trash can.

For more information on respiratory hygiene, see Coughing and Sneezing.

Outbreak Control

A combination of measures can be implemented to control ARI outbreaks, including isolation of infected people, increased infection prevention and control efforts, antiviral chemoprophylaxis of influenza-exposed people, crew member and passenger notifications, and active surveillance for new cases.

Recommendations when a voyage’s crew or passenger ARI attack rate reaches 2%^‡

• Provide all crew members with respirators or well-fitting masks and provide crew with information on how to properly wear, take off, and clean (if reusable)
• Minimize the number of crew members sharing a cabin or bathroom to the extent possible.
• Instruct crew members to remain in cabins as much as possible during non-working hours.
• Cancel nonessential face-to-face employee meetings as well as group events (such as employee trainings) and social gatherings.
• Close all crew bars, gyms, and other group settings.
• Close indoor crew smoking areas.
• Maximize the introduction of outdoor air and adjust HVAC systems to increase total airflow to occupied spaces. For additional information on ventilation, see Ventilation in Buildings
• Maximize air circulation in crew outdoor smoking areas.
• If a COVID-19 outbreak,
  • Expedite contact tracing (including the use of wearable technology, recall surveys, and the onboarding of additional public health staff).
  • Consider serial viral (antigen or NAAT) screening testing of crew every 3–5 days. The onboarding of additional laboratorians may be needed to facilitate the testing process.
• If an influenza outbreak, antiviral chemoprophylaxis can be considered for prevention of influenza in exposed people depending on their risk for complications, or could be given to all contacts on a cruise ship when the threshold is met or exceeded.

Recommendations when a voyage’s crew or passenger ARI attack rate reaches 3%^‡

• Provide all passengers with respirators or well-fitting masks and provide crew with information on how to properly wear, take off, and clean (if reusable)
• Position posters educating passengers on how to properly wear respirators or well-fitting masks in high traffic areas throughout the ship.
• Eliminate self-serve dining options at all crew and officer messes.
• Reduce the dining cohort size for crew, and shorten dining times to avoid crowding.
• Send written notification to passengers on the current, previous, and subsequent voyages informing them of the ARI conditions and measures being taken to reduce transmission on board.
• If a COVID-19 outbreak,
  • Cancel crew shore leave.
  • Implement a “working quarantine” policy for all crew (i.e., crew perform job duties then return to cabin).
  • Require use of respirators or well-fitting masks and provide crew with information on how to properly wear, take off, and clean (if reusable)
  • Test all passengers for COVID-19 prior to the end of the voyage, regardless of their vaccination status. Advise those who test positive or have known exposure to follow guidance following disembarkation.

‡ Sources of data should include medical center records and other established surveillance systems for passengers and crew (e.g., employee illness reports).

Considerations for Suspending Passenger Operations

In some circumstances, additional public health precautions, such as returning to port immediately or delaying the next voyage, may be considered to help ensure the health and safety of onboard travelers or newly arriving travelers.

A ship should consider suspending operations based on the following factors:

• Sustained transmission of ARI, defined as a voyage with:
  • 15% or more of the passengers have met ARI criteria; or
  • 15% or more of the crew have met ARI criteria; or
  • 15% or more of total travelers have met ARI criteria.^[6]
• Severe ARI among passengers or crew resulting in:
  • Shortages of supplemental oxygen or other medical supplies related to management of patients with ARI, or
  • 3 or more deaths due to ARI in passengers and/or crew during a voyage.
• Potential for ARI cases to overwhelm onboard medical center and/or public health resources, defined as the inability to maintain:
  • Adequate staff to:
    • Evaluate symptomatic travelers and their close contacts,
    • Conduct diagnostic and screening testing of travelers,
    • Conduct routine medical checks of travelers in isolation, or
    • Conduct contact tracing of close contacts, if applicable
  • Adequate supplies of:
    • PPE,
    • Testing equipment,
    • Antipyretics (fever-reducing medications such as acetaminophen and ibuprofen),
    • Antivirals and other therapeutics for COVID-19, influenza, and RSV (if commercially available),
    • Oral and intravenous steroids, or
    • Supplemental oxygen
  • Inadequate onboard capacity to fulfill minimum safe manning or minimal operational services, including but not limited to housekeeping and food and beverage services
  • A novel respiratory virus or SARS-CoV-2 variant of concern or a new or emerging SARS-CoV-2 variant with potential for increased severity or transmissibility identified among cases on board

[6] These thresholds are subject to change based on the characteristics of the dominant COVID-19 variant or a novel respiratory virus in the United States or elsewhere.

Reporting

CDC requests that cruise ships submit a cumulative ARI report (even if no ARI cases have occurred) preferably within 24 hours before arrival in the U.S. ^[7], and sooner if a voyage’s crew or passenger ARI attack rate reaches 3% ^[8]. These reports are requested by completing the Cruise Ship Cumulative Acute Respiratory Illness (ARI) Reporting Form. Access to the online reporting form has been provided to cruise lines by CDC. Cruise lines that do not have access may contact CDC (email maritimeadmin@cdc.gov).

In addition, CDC emphasizes that any deaths—including those caused by or suspected to be associated with influenza, COVID-19, RSV, or ARI—that occur aboard a cruise ship destined for a US port must be reported to CDC immediately. Report ARI deaths by submitting an individual Maritime Conveyance Illness or Death Investigation Form [PDF – 4 pages] for each death.

Vessel captains may request assistance from CDC to evaluate or control ARI outbreaks as needed. If the ship will not be arriving imminently at a U.S. seaport, CDC maritime staff will provide guidance to cruise ship officials regarding management and isolation of infected people and recommendations for other passengers and crew members. CDC staff may also help with disease control and containment measures, passenger and crew notification, surveillance activities, communicating with local public health authorities, obtaining and testing laboratory specimens, and provide additional guidance as needed.

[7] For international voyages with >1 U.S. port (e.g., Canada to multiple Alaskan ports), please submit report to CDC within 24 hours before arrival in the final U.S. port.

[8] For international voyages with >15 days prior to arrival in the U.S., the time period for calculating this attack rate begins at day 15 prior to arrival at a U.S. port.

Infection Prevention and Control

Infection prevention and control (IPC) are critical to reducing the spread of ARI. Each cruise ship should maintain a written Infection Prevention and Control Plan (IPCP) that details standard procedures and policies to specifically address infection control and cleaning/disinfection procedures to reduce the spread of ARI.

To reduce the spread of ARI, cruise ship operators should include the following as part of a written IPCP:

• Duties and responsibilities of each department and their staff for all passenger and crew public areas
• A graduated approach for escalating infection prevention and control measures in response to ARI cluster or outbreaks during a voyage with action steps and criteria for implementation
• Procedures for informing passengers and crew members that a threshold of ARI has been met or exceeded, and of any recommended or required measures to prevent spread of infection
• Procedures to protect crew from occupational exposures to respiratory viruses, including crew responsible for cleaning potentially contaminated surfaces, laundry staff, and those entering cabins or other areas where people with confirmed or suspected respiratory virus infections are present.
  • Crew members entering cabins or other areas where people with confirmed or suspected COVID-19 are should be limited, and crew should wear an NIOSH Approved® N95® filtering facepiece respirator or higher in accordance with the Occupational Safety and Health Administration’s (OSHA) Respiratory Protection standard (29 CFR 1910.134)
• Disinfectant products or systems used, including the surfaces or items the disinfectants will be applied to, concentrations, and required contact times
• Procedures to protect passengers and crew from exposure to disinfectants, if not already included in the ship’s safety management system. At a minimum, this should include the following:
  • Safety data sheets (SDSs)
  • PPE recommendations for crew, which may include surgical masks or NIOSH Approved® N95® filtering facepiece respirators or higher, eye protection such as goggles or disposable face shields that cover the front and sides of the face, and disposable medical gloves and gowns in addition to those recommended by the disinfectant manufacturer in the SDS; for information on health hazards related to disinfectants used against viruses, see Hazard Communication for Disinfectants Used Against Viruses.
  • Health and safety procedures to minimize respiratory and dermal exposures to both passengers and crew, when recommended
• Graduated procedures for returning the vessel to normal operating conditions after a threshold of ARI has been met, including de-escalation of cleaning and disinfection protocols

Frequent, routine cleaning and disinfection of commonly touched surfaces with an Environmental Protection Agency (EPA)-registered disinfectant is recommended. For COVID-19, EPA-registered disinfectant effective against coronaviruses is strongly recommended.

Attribution Statement

N95 and NIOSH Approved are certification marks of the U.S. Department of Health and Human Services (HHS) registered in the United States and several international jurisdictions.