Public Health Guidance for Potential COVID-19 Exposure Associated with Travel
CDC recommends getting fully vaccinated before traveling. International travel may pose additional risks, and even fully vaccinated travelers may be at increased risk for getting and spreading some SARS-CoV-2, the virus that causes COVID-19, variants.
Cruise ships in U.S. waters or intending to return to U.S. waters must continue to follow CDC’s Framework for Conditional Sailing Order (CSO) and the Technical Instructions for Mitigation of COVID-19 Among Cruise Ship Crew.
Summary of Recent Changes
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, the proportion of travelers who are fully vaccinated will continue to increase. Travel-associated transmission risk is likely to be substantially reduced among those fully vaccinated. However, global circulation of SARS-CoV-2 variants of concern, vaccine performance against emerging variants, and global vaccination coverage remain a concern.
People are considered fully vaccinated for COVID-19 ≥2 weeks after they have received the second dose in a 2-dose series (Pfizer-BioNTech or Moderna), or ≥2 weeks after they have received a single-dose vaccine (Johnson & Johnson [J&J]/Janssen).
Note: At this time, there are limited data on vaccine effectiveness in people who are immunocompromised, including those taking immunosuppressive medications. See considerations for fully vaccinated people who are immunocompromised.
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.
CDC’s requirements, recommendations, and considerations for public health management of international and domestic travelers are provided below. Health departments have the authority to 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.
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 requires all air passengers 2 years of age or older coming to the United States, 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”) conducted no more than 3 days before their flight’s departure. Passengers who have had a positive viral test in the past 3 months (or the time period specified in CDC guidance) 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 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.
U.S. Predeparture Testing Recommendations for Outbound International Travelers and Domestic Travelers
Travelers who are fully vaccinated or who have recovered from COVID-19 in the past 3 months do not need to get tested before departing the United States for international travel or before domestic travel unless their destination requires it. For those who are not fully vaccinated and have not recovered from COVID-19 in the past 3 months, CDC recommends predeparture testing with a viral test no more than 3 days before departure for travelers departing from the United States for international destinations or traveling domestically within the United States.
CDC modeling indicates that predeparture testing is most effective when combined with self-monitoring for symptoms of COVID-19.1 Travel should be delayed (i.e., individuals should self-isolate) if symptoms develop or a pre-departure test result is positive. Testing before departure results in the greatest reduction of transmission risk during travel when the specimen is collected close to the time of departure. Testing more than 3 days before travel provides little benefit beyond what self-monitoring alone can provide. Furthermore, a lower sensitivity test (e.g., antigen test) closer to the time of travel (i.e., with rapid availability of results) can be as effective as, or more effective than, a higher sensitivity NAAT (e.g., reverse transcription polymerase chain reaction test [RT-PCR]) performed several days before travel. Predeparture testing should be completed and results provided to the traveler before travel is initiated. Travelers who test positive should remain in isolation and delay travel until they meet criteria for discontinuing isolation. Travelers whose test results are not available before departure should delay their travel until results are available.
CDC modeling indicates that testing on the day of travel provides the greatest reduction in transmission risk while traveling.1 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 jurisdiction. Ideally, 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.
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 do not need 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.
- Fully vaccinated international travelers arriving in the United States are still 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 who are not fully vaccinated and have not recovered from COVID-19 in the past 3 months (international and domestic)
- These travelers are still 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 avoid contact with people at increased risk for severe illness for 14 days, regardless of testing.
Travelers who recovered from COVID-19 in the past 3 months
- Travelers who tested positive for SARS-CoV-2 in the past 3 months and have met criteria to discontinue isolation do not need to get a SARS-CoV-2 viral test or self-quarantine after travel unless they are symptomatic.
Below we provide technical considerations for U.S. health departments in developing their strategies for post-arrival management of travelers, including the timing of testing and using testing in combination with other measures.
Rationale and Evidence for Travel-associated Public Health Recommendations for Fully Vaccinated Travelers
Public health decisions regarding relaxing travel-related recommendations for those who are fully vaccinated should 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. Testing and quarantine are resource-intensive prevention measures that impose a burden on public health resources, individual travelers, workplaces, and communities. In circumstances where SARS-CoV-2 incidence is low, many tests may be needed to identify a small number of infected travelers. Many uninfected travelers may also undergo unnecessary quarantine, which could result in an undue burden of missed work (including for essential workers) or school.
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 efficacy rates and limited data regarding effectiveness, including against circulating variants; estimates were based solely on data available from the three vaccines authorized in the United States.
Preliminary data from Israel suggest that people vaccinated with the Pfizer-BioNTech COVID-19 vaccine who develop COVID-19 have a four-fold lower viral load than unvaccinated people.3 This observation may indicate reduced transmissibility, as viral load has been identified as a key driver of transmission.3,4
Vaccinated travelers may thus be less likely to be infected (VES: susceptibility) and to transmit to others if infected (VEI: infection). Early estimates of VES for the Pfizer-BioNTech vaccine are on the order of 60–92%. Therefore, a range of combined VES and VEI estimates from 60–90% for vaccinated travelers was assessed. For example, with a combined VE of 60%, 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 and 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. 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.
With a 90% effective vaccine, pre-travel testing, post-travel testing, and 7-day self-quarantine provide minimal additional benefit. When adhered to, a pre-travel test plus a 7-day post-arrival self-quarantine for unvaccinated travelers is >30% more effective at reducing risk compared to travelers vaccinated with a 60% effective vaccine (Table 1).
Population-level vaccination coverage and travel
Two other factors may contribute to risk associated with travel: (1) the risk of infection at the origin location of the traveler and (2) the risk of transmission at the destination. Both of these factors are influenced by vaccination coverage rates. With increasing vaccination coverage in populations at origins and destinations, the infection and transmission risks for the traveler would be reduced (Figure 1). This provides additional risk reductions, proportional to coverage and effectiveness, for both vaccinated and unvaccinated travelers.
There are many factors that are unknown for international travel such as effectiveness of non–FDA-authorized vaccines, vaccination coverage in populations at origins and destinations, circulating SARS-CoV-2 variants, and vaccine effectiveness against these variants. Therefore, pre- and post-travel testing may provide an additional layer of risk reduction for international travelers without the additional burden of self-quarantine.
Figure 1: Impact of origin and destination vaccine coverage and vaccine efficacy (combined VES and VEI) of 60% and 90% on introduction risk reduction
With 60% combined VE 100% of people in the origin location vaccinated, and 0% in the destination location, there is a 60% reduction in the risk of introduction by an exposed traveler at the destination compared to if there were no vaccination in either population. However, if 50% of the destination population is also vaccinated, that reduction increases to 72%. If both populations have full vaccination coverage, the reduction is 84%. The absolute risk (i.e., considering prevalence of infection not just vaccination) is lower as transmission is unlikely to be widespread in the origin location with 100% vaccine coverage. With 90% combined VE, substantial reductions occur at lower vaccination coverage proportions.
Table 1: Model results examining percent risk reduction relative to baseline where unvaccinated individual is exposed at origin and takes no precautions
|Post-travel risk reduction|
|Vaccine effectiveness against infection||Pre-travel testa||7-day quarantine||Post-travel test day 3–5||Median||Min||Max|
a Pre-travel test 1–3 days before departure as required for all people entering the United States5 and recommended for other travelers. It is assumed that if a pre- or post-travel test is positive, the traveler does not travel or isolates, respectively, until recovered.
These findings suggest that any travel-associated transmission risk is likely to be substantially reduced among those fully vaccinated with an effective vaccine. The risks of SARS-CoV-2 infection in fully vaccinated travelers cannot be completely eliminated in the setting of continued widespread transmission. Travel presents opportunities for onward viral transmission due to mixing of individuals throughout the travel journey. It is not fully known how vaccination will impact infection and forward transmission. However, the evidence suggests that with an effective vaccine and increasing vaccination coverage, the burden of testing and quarantine is much higher than any marginal additional risk reduction provided for the fully vaccinated traveler. Taking into consideration the factors outlined above, CDC has updated both domestic and international travel guidance.
However, with inconsistent and from country to country, and because vaccine effectiveness data were limited to those receiving a subset of globally available vaccines, the analyses described here should not be extrapolated to other vaccines. Global circulation of SARS-CoV-2 variants and vaccine performance against emerging variants are also important considerations when evaluating the need for continued prevention measures in vaccinated people and will require continued monitoring. As such, CDC will continue to require a negative SARS-CoV-2 test result or documentation of recovery from COVID-19 for all air passengers departing for the United States5 and continues to recommend a post-arrival test for international travelers arriving to the United States. CDC continues to review available data and will update travel guidance accordingly.
Below, we provide technical considerations for U.S. health departments in developing their strategies for post-arrival management of travelers who are not fully vaccinated, including the timing of testing and using testing in combination with other measures.
Note: These considerations are specifically intended for management of asymptomatic not fully vaccinated travelers with no known exposures to a person with COVID-19. They are not intended to be used in developing policies for management of not fully vaccinated individuals with probable or confirmed COVID-19 or those who have had close contact with a person with COVID-19.
Technical Considerations on Testing and Post-arrival Management for Travelers who are not Fully Vaccinated (based on CDC modeling)
Mathematical models have provided some insights into potential effects of testing and various quarantine periods. CDC modeling suggests that, when combined with post-arrival testing and self-monitoring for symptoms of COVID-19 (with subsequent isolation for those who test positive or develop symptoms), the period of staying home (self-quarantine) or in a comparable location such as a hotel (referred to as the “stay-at-home period” in the remainder of this section) can be shortened without substantially increasing the risk of introducing additional cases of COVID-19 to the destination community.1
The optimal post-arrival test timing and reduction in risk of introducing additional cases of COVID-19 at destination (referred to as “transmission risk” in the remainder of this section) vary depending on what other measures are taken. The scenarios below assume all travelers self-monitor for symptoms of COVID-19 and self-isolate if symptoms develop.
Stay-at-home (Self-quarantine) Period with or without Post-arrival Testing
- A CDC modeling study examined several combinations of 7 or 14-day post-travel self-quarantine, pre-travel testing, and post-arrival testing and their potential effect on post-travel transmission risk.1
- Considerations such as the likelihood of compliance, and burden of mitigation measures on the individual are also important to account for in developing recommendations and policies aimed to reduce travel-related COVID-19 spread.
- 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
- CDC. Science Brief: COVID-19 Vaccines and Vaccination. Centers for Disease Control and Prevention. Published February 11, 2020. Accessed June 9, 2021. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/fully-vaccinated-people.html
- Levine-Tiefenbrun M, Yelin I, Katz R, et al. Decreased SARS-CoV-2 viral load following vaccination. medRxiv. Published online 2021.
- 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.
- CDC. Requirement for Proof of Negative COVID-19 Test or Recovery from COVID-19 for All Air Passengers Arriving in the United States. Centers for Disease Control and Prevention. Published February 11, 2020. Accessed May 18, 2021. https://www.cdc.gov/coronavirus/2019-ncov/travelers/testing-international-air-travelers.html
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. Individuals who are not fully vaccinated and 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 iconexternal 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 email@example.com). The aircraft operator should also coordinate with the US embassy or consulateexternal icon for the country where the individual is located, CDC, the Federal Aviation Administration, and US 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.
CDC supports domestic COVID-19 control efforts by making contact information for international air passengers available to state and local health departments for the purpose of public health follow-up or contact tracing. At present, collection of traveler contact information is occurring for passengers from countries subject to entry restrictions under Presidential Proclamation.
Follow-up with travelers may include contacting 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.
CDC and the Federal Aviation Administration have jointly provided Updated Interim Occupational Health and Safety Guidance for Air Carriers and Crewspdf iconexternal icon. Please refer to the document for up-to-date recommendations.
As of April 27, 2021
- Added vaccines with emergency approval from the World Health Organization to the definition of “fully vaccinated”
As of April 1, 2021
- Added CDC’s recommendations for fully vaccinated travelers and those who recently recovered from COVID-19.
As of February 2, 2021
- Added CDC’s requirement for wearing masks on public transportation conveyances and in transportation hubs
- Added CDC’s requirement for predeparture testing of arriving international air passengers
- Aligned with updated CDC messaging to travelers
As of January 19, 2021
- Updated Individuals with Confirmed or Probable COVID-19 or Known Exposure to Someone with COVID-19 section and added a link to new guidance.
As of December 2, 2020
- Added recommendations for predeparture and post-arrival testing and new considerations for post-arrival management of international travelers
As of October 19, 2020
- Added information about transport of individuals with confirmed or probable COVID-19 or known exposure to someone with COVID-19.
As of August 3, 2020
- Added section for Individuals with Confirmed or Probable COVID-19 or Known Exposure to Someone with COVID-19.
- Added Traveler Contact Information section.
1 This guidance applies to COVID-19 vaccines currently authorized for emergency use by the U.S. Food and Drug Administration: Pfizer-BioNTech, Moderna, and Johnson and Johnson (J&J)/Janssen COVID-19 vaccines. This guidance can also be applied to COVID-19 vaccines that have been authorized for emergency use by the World Health Organization (e.g. AstraZeneca/Oxford).