Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Public Health Guidance for Potential COVID-19 Exposure Associated with Travel

Public Health Guidance for Potential COVID-19 Exposure Associated with Travel
Updated Dec. 2, 2021

CDC recommends getting fully vaccinated before traveling within the United States or internationally. International travel may pose additional risks, and even fully vaccinated travelers may be at increased risk for getting and spreading some variants of SARS-CoV-2, the virus that causes COVID-19.

CDC has separate guidance for exposures in healthcare personnel and critical infrastructure workers, and for quarantine of contacts of persons with COVID-19.

Cruise ships in U.S. waters or intending to return to U.S. waters must continue to follow CDC’s Temporary Extension and Modification of the Conditional Sailing Order  and the Technical Instructions for Mitigation of COVID-19 Among Cruise Ship Crew.

Summary of Recent Changes

View Previous Updates


Individuals who travel may be at risk for exposure to SARS-CoV-2, the virus that causes COVID-19, before, during, or after travel. This could result in travelers spreading the virus to others at their destinations or upon returning home.

As part of a broader strategy aimed to limit continued new introduction of SARS-CoV-2 and the emergence of new SARS-CoV-2 variants in U.S. communities, all travelers should remain vigilant for signs and symptoms of COVID-19. Travelers should also take recommended precautions to limit community spread after traveling from one location to another. CDC has issued requirements and recommendations to prevent travel-associated exposure to and transmission of SARS-CoV-2.

As vaccination efforts continue across the United States and internationally, the proportion of travelers who are fully vaccinated will continue to increase. Travel-associated transmission risk substantially reduced among those fully vaccinated. However, global circulation of SARS-CoV-2 variants of concern, variants being monitored, vaccine performance against emerging variants, and global vaccination coverage remain concerns.

For the purpose of this guidance, “fully vaccinated against COVID-19” is defined as in Technical Instructions for Implementing Presidential Proclamation Advancing Safe Resumption of Global Travel During the COVID-19 Pandemic and CDC’s Order.

Audience and Purpose

This page provides U.S. public health officials with an overview of CDC’s requirements, recommendations, and considerations for management of vaccinated and unvaccinated domestic and international travelers.

Requirements, Recommendations, and Considerations

CDC’s requirements and recommendations for public health management of international and domestic travelers are provided below. Health departments have the authority to take actions that exceed CDC recommendations in their jurisdictions. Travelers should additionally follow guidance and requirements of destination countries for international travel, or state, tribal, local, and territorial authorities when arriving in a U.S. jurisdiction after international or domestic travel.

Mask Requirement

As of February 2, 2021, CDC requires wearing masks on planes, buses, trains, and other forms of public transportation traveling into, within, or out of the United States and while indoors at U.S. transportation hubs such as airports and stations. Travelers are not required to wear a mask in outdoor areas of a conveyance (like a ferry or top deck of a bus). See more information about this requirement.

Predeparture Testing Requirement for International Air Passengers Traveling to the United States

CDC issued an Order (amended December 2, 2021) that requires all air passengers aged two years or older, including U.S. citizens and those who are fully vaccinated, to present a negative COVID-19 test result from a nucleic acid amplification test (NAAT) or antigen test (“viral test”) before boarding a flight to the United States from a foreign country. This test must be conducted no more than 1 day before their flight’s departure. Passengers who have had a positive viral test in the past 90 days and have met the criteria to discontinue isolation may travel with documentation of recovery from COVID-19. This documentation of recovery must include their positive viral test result from a specimen collected in the 90 days before the flight, and a letter from a licensed healthcare provider or a public health official that states the individual is cleared for travel. More information about this requirement is available in the Frequently Asked Questions for air passengers arriving in the United States.

Vaccine Requirement

On October 25, 2021, the President issued a Proclamationexternal icon titled “Advancing the Safe Resumption of Global Travel During the COVID-19 Pandemic” to suspend and restrict the entry of noncitizen nonimmigrants who are not fully vaccinated against COVID-19 and seeking to enter the United States by air travel. The Proclamation directs the CDC Director to implement the Proclamation as it applies to public health in accordance with appropriate public health protocols. CDC’s Order and accompanying Technical Instructions implement the President’s direction. As a condition of entering the United States by air, noncitizen nonimmigrants must present proof of being fully vaccinated against COVID-19 before boarding a flight to the United States. The Proclamation excepts certain categories of noncitizen nonimmigrants who are not fully vaccinated. These individuals must obtain a viral test for COVID-19 after arrival and self-quarantine or self-isolate; some must also become fully vaccinated after arrival. For more information about these requirements, see the Frequently Asked Questions.

Travelers Prohibited from Entry to the United States

With specific exceptions, noncitizens who have been in certain countries during the past 14 days may not enter the United States, either as immigrants or nonimmigrants. For more information, visit Travelers Prohibited from Entry to the United States.

U.S. Post-arrival Testing and Management Recommendations

The following are CDC’s recommendations for travelers arriving in a U.S. jurisdiction based on vaccination status.

Fully vaccinated travelers

Domestic travel (within the United States or to a U.S. territory):

  • Fully vaccinated travelers are not recommended to get a SARS-CoV-2 viral test after domestic travel, unless they are symptomatic or testing is required by local, state, or territorial health authorities.
  • Fully vaccinated travelers do not need to self-quarantine following domestic travel.

International travel:

  • Fully vaccinated international travelers arriving in the United States are recommended to get a SARS-CoV-2 viral test 3-5 days after travel.
  • Fully vaccinated travelers do not need to self-quarantine in the United States following international travel.

Travelers of any age who are not fully vaccinated and have not recovered  from COVID-19 (tested positive for SARS-CoV-2 and met criteria to discontinue isolation) in the past 90 days (domestic and international)


  • These travelers are recommended to have a post-arrival test 3-5 days after arrival at destination, combined with self-monitoring and a 7-day period of staying home (or in a comparable location such as a hotel room) or otherwise self-quarantining.
    • The 7-day period should be completed even if the test is negative.
    • In the absence of testing, this period should be extended to 10 days.


  • These travelers are recommended to have a post-arrival test 3-5 days after arrival at destination, combined with self-monitoring and a 7-day period of staying home (or in a comparable location such as a hotel room) or otherwise self-quarantining.
    • The 7-day period should be completed even if the test is negative.
    • In the absence of testing, this period should be extended to 10 days.
    • Travelers should self-isolate if the viral test is positive or they develop symptoms of COVID-19.
  • However, under CDC’s Order implementing the Presidential Proclamation, excepted noncitizen nonimmigrants arriving as air passengers who are not fully vaccinated against COVID-19 are required to:
    • Have a post-arrival viral test 3-5 days after arrival at their U.S. destination, unless they have documentation of having recovered from COVID-19 in the past 90 days;
    • Self-quarantine for 7 days, even if the test is negative, unless they have documentation of having recovered from COVID-19 in the past 90 days;
    • Self-isolate if the viral test is positive or they develop symptoms of COVID-19; and
    • If they intend to stay in the United States longer than 60 days, become fully vaccinated against COVID-19 within 60 days of arriving in the United States, or as soon as thereafter as is medically appropriate, unless they are ineligible because of age or have a medical contraindication to receiving a COVID-19 vaccine.

Travelers who recovered from COVID-19 in the past 90 days

  • Travelers who tested positive for SARS-CoV-2 in the past 90 days and have met criteria to discontinue isolation do not need to get a SARS-CoV-2 viral test or self-quarantine after travel.

Those who develop COVID-19 symptoms should self-isolate and consult with a healthcare provider for testing recommendations.

Rationale and Evidence for Travel-associated Public Health Recommendations for Fully Vaccinated Travelers

Public health decisions regarding travel-related recommendations and requirements for those who are fully vaccinated and those who are not fully vaccinated take into account all available evidence, including vaccine effectiveness for preventing SARS-CoV-2 infection and transmission. Individual and societal factors are also important when evaluating the benefits and potential harms of prevention measures among vaccinated travelers.

COVID-19 vaccines approved or authorized in the United States offer substantial protection against severe illness, hospitalization, and death from COVID-19, including from the Delta variant. However, breakthrough infections can occur in fully vaccinated people. Data suggest lower effectiveness against confirmed infection and symptomatic disease caused by Delta variant. However, fully vaccinated persons are less likely than unvaccinated persons to acquire SARS-CoV-2, and infections in fully vaccinated persons are associated with less severe clinical outcomes. A growing body of evidence also suggests that COVID-19 vaccines also reduce asymptomatic infection and transmission.

The relative introduction risk reduction, or the expected reduction in the risk of SARS-CoV-2 introduction to a destination population from an infected traveler, was modeled based on different estimates of infectiousness and mitigation measures (i.e., pre-travel testing, post-travel testing, and post-travel quarantine) using methods in Johansson et al (2021)1. Briefly, the model inputs for infection components include: the relative infectiousness over the course of infection, the proportion of infections resulting in symptoms, the timing of symptom onset for those who have symptoms, and the probability of testing positive over the course of infection. The model inputs for intervention components include: test type, test sensitivity, test timing, vaccination effectiveness (against infection and transmission), and vaccine coverage. The model output is relative introduction risk reduction.

Impact of prevention measures for travelers in the context of vaccination

To assess the feasibility of eliminating post-travel testing and self-quarantine recommendations for vaccinated travelers, data from studies that evaluated vaccine effectiveness for infection prevention (regardless of symptoms) were reviewed.2 To estimate the impact of vaccination combined with other measures, a range of vaccine effectiveness was used in models previously developed to assess testing and quarantine prevention measures.1 There are currently several vaccines available globally with varying effectiveness rates and limited data regarding effectiveness, including against circulating variants; estimates were based solely on data available from the three vaccines currently authorized or approved in the United States.

Fully vaccinated travelers may be less likely to be infected (VEI: infection) and to transmit to others if infected (VET: transmission) because vaccinated people appear to spread the virus for a shorter time.3 Early estimates of VEI for the Pfizer-BioNTech vaccine are on the order of 60–92%. Therefore, a range of combined VEI and VET estimates from 60–90% for vaccinated travelers was assessed. For example, with a VE(I+T) of 60% referred to as a combined VE, a traveler, who if unvaccinated would be infected and infectious 100% of the time, was assumed to be infected and infectious 40% of the time. With a combined VE of 90%, the traveler was assumed to be infected and infectious 10% of the time. In all scenarios, it was assumed that travelers were tested by real time reverse transcription polymerase chain reaction (RT-PCR) or antigen test 1–3 days before departure. Because of the value of testing close to the time of travel, a lower sensitivity test with faster results can be more effective operationally despite decreased sensitivity.1 Symptom monitoring was not included in any scenario and, when included in the model, all travelers were assumed to adhere to a post-travel self-quarantine for 7 days. In some scenarios, a post-arrival test at day 3–5 was added.

Population-level vaccination coverage and travel

Risk of infection at the origin location of the traveler and risk of transmission at the destination are influenced by local vaccination coverage rates. With increasing vaccination coverage in populations at origins and destinations, the relative introduction risks for the traveler would be reduced (Figure 1). Additional risk reductions for both vaccinated and unvaccinated travelers would be proportional to vaccine coverage and effectiveness.

There are many factors that are unknown for international travel such as effectiveness of some non–FDA-authorized vaccines, vaccination coverage in populations at origins and destinations, emerging SARS-CoV-2 variants, and vaccine effectiveness (VE) against these variants. Therefore, pre- and post-travel testing provides an additional layer of risk reduction for fully vaccinated international travelers without the additional burden of self-quarantine.

Figure 1: Modeled impact of origin and destination vaccine coverage and vaccine effectiveness (combined effectiveness against infection and transmission) of 60% and 90% on introduction risk reduction

image of Impact of origin and destination vaccine coverage and vaccine efficacy

With 60% combined VE (against infection and transmission), 100% of people in the origin location vaccinated, and 0% in the destination location, there is an estimated 60% reduction in the relative risk of introduction of SARS-COV-2 to the destination by an exposed traveler, compared to if there were no vaccination in either population. However, if 50% of the destination population were also vaccinated, that reduction would increase to an estimated 72%. If both populations have full vaccination coverage, the relative risk reduction would be an estimated 84%. With 90% combined VE against infection and transmission, substantial reductions would occur at lower vaccination coverage proportions.

Table 1: Model results examining relative reduction in introduction risk compared with baseline where unvaccinated individual is exposed at origin with no pre-travel testing, quarantine, or post-travel testing

Table 1
Post-travel risk reduction
Vaccine effectiveness against infection Pre-travel testa 7-day quarantine Post-travel test day 3–5 Median Min Max
No vaccine 0% 0% 0%
No vaccine 13.6% 4.5% 35.5%
No vaccine 43.3% 19.7% 66.0%
No vaccine 92.4% 66.2% 94.7%
No vaccine 97.1% 85.8% 98.9%
60% 60.0% 60.0% 60.0%
60% 65.4% 61.8% 74.2%
60% 77.3% 67.9% 86.4%
60% 97.0% 86.5% 97.9%
60% 98.9% 94.3% 99.6%
70% 70.0% 70.0% 70.0%
70% 74.1% 71.4% 80.6%
70% 83.0% 75.9% 89.8%
70% 97.7% 89.9% 98.4%
70% 99.1% 95.7% 99.7%
80% 80.0% 80.0% 80.0%
80% 82.7% 80.9% 87.1%
80% 88.7% 83.9% 93.2%
80% 98.5% 93.2% 98.9%
80% 99.4% 97.2% 99.8%
90% 90.0% 90.0% 90.0%
90% 91.4% 90.5% 93.5%
90% 94.3% 92.0% 96.6%
90% 99.2% 96.6% 99.5%
90% 99.7% 98.6% 99.9%

a Model assumes pre-travel test 1–3 days before departure. It is assumed that if a pre- or post-travel test is positive, the traveler does not travel or isolates after arrival, respectively, until recovered.

Pre-travel test timing and risk reduction

For individuals not fully vaccinated, the timing of the pre-travel test is important to reduce the risk of introduction of COVID-19 to the destination.  CDC models show that for persons not fully vaccinated, getting a NAAT or antigen test one day before departure can reduce the risk of COVID-19 importation to the destination by 40%. When this window is expanded to two days before departure, this risk reduction is 26%, and for three days before departure, the risk reduction is only an estimated 14%. Among travelers fully vaccinated with a vaccine that has 60% effectiveness against SARS-CoV-2 infection, getting tested with a NAAT or antigen test 3 days before departure, the combination of vaccination and testing can reduce introduction risk by 66%. Decreasing this testing window to two days increases this risk reduction to 71%, and to 76% with testing one day before travel for fully vaccinated travelers. Therefore, there is limited advantage to shortening the time period for testing for fully vaccinated air travelers.± The combination of vaccination and pre-travel testing provides a greater level of protection than either measure alone and is consistent with a layered strategy (Table 2).

Table 2
Vaccination status Vaccine effectiveness against infection Pre-travel risk reduction by test day (%)

Median (min, max)a

72 hours 48 hours 24 hours
Not fully vaccinated NA 13.5 (6.5, 27.5) 25.5 (13.5, 42) 40 (23.5, 56)
Fully vaccinated 60 65.5 (62.5, 71) 70.5 (65.5, 77) 76 (69.5, 82.5)
Fully vaccinated 80 83 (81.5, 85.5) 85 (83, 88.5) 88 (84.5, 91.5)

a NAAT or antigen test

These findings indicate that any travel-associated transmission risk is substantially reduced among those fully vaccinated with an effective vaccine. However, the risks of SARS-CoV-2 infection in fully vaccinated travelers cannot be eliminated in the setting of continued widespread transmission. Global circulation of SARS-CoV-2 variants, vaccine performance against emerging variants, and the potential for waning immunity from vaccination over time are important considerations when evaluating the need for continued or new prevention measures in vaccinated people and will require continued monitoring. CDC continues to review available data and will update travel guidance and requirements accordingly.

The above models were based on data collected before the Omicron variant was identified and may not apply to the Omicron variant. As more data become available about the transmissibility of and the effectiveness of COVID-19 vaccines against Omicron, CDC will update these models.


  1. Johansson MA, Wolford H, Paul P, et al. Reducing travel-related SARS-CoV-2 transmission with layered mitigation measures: symptom monitoring, quarantine, and testing. BMC Med. 2021;19(1):94. doi:10.1186/s12916-021-01975-w
  2. Science Brief: COVID-19 Vaccines and Vaccination. Centers for Disease Control and Prevention. Published February 11, 2020. Accessed June 9, 2021.
  3. Chia PY, Ong SWX, Chiew CJ, et al. Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multi-center cohort study Preprint at medRxiv https://doi. org/10.1101/2021.07.28.21261295 Published online 2021..
  4. Marks M, Millat-Martinez P, Ouchi D, et al. Transmission of COVID-19 in 282 clusters in Catalonia, Spain: a cohort study. The Lancet Infectious Diseases. Published online 2021.

Considerations for Testing in Airport Settings

Airport testing sites may also be a convenient option for some travelers. However, for logistical reasons (e.g., rebooking of travel and avoiding potential exposures in airport terminals where social distancing may be challenging), CDC recommends departing air travelers whose destinations require testing get tested before they initiate travel, rather than at the airport immediately prior to their flight.  If testing is offered in airport  settings, all results (positive or negative) must be reported in real time to the health department of jurisdiction, and positive results in departing air travelers should be reported immediately to both the local health department and the CDC quarantine station of jurisdictionIdeally, travelers’ consent should also be obtained before testing to notify the airline of a positive result. Plans should also be in place to prevent travel of persons who test positive and their travel companions who are not fully vaccinated or have COVID-19 symptoms, who in most cases would be considered close contacts, including request by the health department to CDC for use of federal public health travel restrictions and denial of boarding by the airline (see section below). Testing sites should also have plans to manage individuals who test positive and their travel companions, including temporary isolation or quarantine and safe private transportation home that does not involve public transportation.

Individuals with Confirmed or Probable COVID-19 and Those Who Are Not Fully Vaccinated Who Have a Known Exposure to Someone with COVID-19

Individuals with confirmed or probable COVID-19 should remain in isolation and delay travel until they meet criteria for discontinuing isolation. Unless they are fully vaccinated or recovered from COVID-19 in the past 90 days, individuals who have been exposed (i.e., close contacts) to a person with confirmed COVID-19 should remain in quarantine and delay travel until they meet criteria for release from quarantine. Health departments may request use of federal public health travel restrictions for individuals with confirmed COVID-19 or with known exposure, if they intend to travel before being cleared to do so by public health authorities, by contacting the CDC quarantine station with jurisdiction for the area where the person is located.

If travel is necessary (e.g., to obtain medical care that is not available locally), transportation should be conducted in a manner that does not expose conveyance operators (e.g., air crews, bus drivers) or other travelers. The mode of transportation should be guided by distance (e.g., ground vs. air transportation) to the final destination as well as the clinical condition of the traveler (i.e., whether medical care may be needed en route).

  • Options for travelers with confirmed or probable COVID-19 are private vehicles, chartered or private aircraft, or medical transport (i.e., ground or air ambulance) with infection control precautions in place to protect vehicle operators and medical personnel.
  • Options for travelers with known exposure to someone with COVID-19 are private vehicles or chartered or private aircraft with precautions in place to protect air crews.

For international transport with a destination within the United States, per CDC regulations (42 Code of Federal Regulations, Part 71: Foreign Quarantineexternal icon), the conveyance operator must notify CDC in advance through the CDC quarantine station with jurisdiction for the port of entry or the CDC Emergency Operations Center (770-488-7100 or The aircraft operator should also coordinate with the U.S. embassy or consulateexternal icon for the country where the individual is located, CDC, the Federal Aviation Administration, and U.S. Customs and Border Protection, as well as appropriate foreign, state, local, territorial, and tribal governments to ensure compliance with all applicable laws and regulations. For more information see Interim Guidance for Transporting or Arranging Transportation by Air into, from, or within the United States of People with COVID-19 or COVID-19 Exposure.

International Air Passenger Contact Information

CDC supports domestic COVID-19 control efforts by making contact information (e.g., physical address in the United States, telephone number, email address) for international air passengers available to state and local health departments for the purpose of public health follow-up, as needed. On October 25, 2021, CDC issued an Order requiring airlines and other aircraft operators to collect designated contact information for all air passengers before they board a flight to the United States from a foreign country and to provide the data to CDC within 24 hours of a request. Effective November 30, 2021, CDC directs pdf icon[88 KB, 3 pages] airlines and aircraft operators carrying passengers that have been in the Republic of Botswana, the Kingdom of Eswatini, the Kingdom of Lesotho, the Republic of Malawi, the Republic of Mozambique, the Republic of Namibia, the Republic of South Africa, or the Republic of Zimbabwe during the 14 days before their flight to the United States to transmit these passengers’ contact information to CDC. CDC will share these data with health departments for the purpose of conducting aircraft contact investigations or as indicated to mitigate risk of SARS-CoV-2 importation associated with international travel.

Follow-up with travelers may include establishing communications with travelers, providing instructions for what travelers should do if they develop illness compatible with COVID-19, follow-up of test results, and intermittent check-ins during the post-arrival period. Mobile applications or automated text messaging may be useful to provide information to travelers or conduct monitoring of travelers. Follow-up with travelers is at the discretion of health departments and may be considered by jurisdictions that are implementing containment measures. Decisions about whether to conduct follow-up and what it would involve could be based on the status of the COVID-19 outbreak in the jurisdiction, status of the COVID-19 outbreak in travelers’ countries or states of origin, the volume of travelers, available resources, competing priorities of public health officials, and other factors, as applicable.

Crews on Passenger or Cargo Flights

CDC and the Federal Aviation Administration have jointly provided Updated Interim Occupational Health and Safety Guidance for Air Carriers and Crews.pdf iconexternal icon Please refer to the document for up-to-date recommendations.

Previous Updates

± CDC recommends that fully vaccinated cruise ship passengers receive a COVID-19 PCR or rapid antigen test no more than 2 days before boarding or on embarkation day (see COVID-19 Operations Manual for Simulated and Restricted Voyages under the Framework for Conditional Sailing Order). While cruise ships share similarities with other forms of travel, including air travel, cruise ships represent a unique environment that facilitates the spread of COVID-19 based on such factors as their larger size, with larger cruises of more than 6,000 passengers, and ability to bring an international cohort of passengers and crew together for days or weeks at a time through frequent events such as group and buffet dining, entertainment events, and excursions. Accordingly, testing, and other public health recommendations for cruise ships and air travel may differ.