How CDC Determines the Level for COVID-19 Travel Health Notices
CDC uses Travel Health Notices (THNs) to alert travelers and other audiences to health threats around the world and how to protect themselves. On November 21, 2020, CDC adapted its 3-level notice system to a new 4-level system for COVID-19 and updated criteria used to determine THN levels.
COVID-19 Travel Health Notice information can be found in two places:
- An interactive world map which shows COVID-19 travel recommendations by destination
- CDC’s COVID-19 Travel Health Notice webpage
This new 4-level system categorizes destinations, including international destinations and United States Territories, into the following four levels:
- Level 4: Very high level of COVID-19
- Level 3: High level of COVID-19
- Level 2: Moderate level of COVID-19
- Level 1: Low level of COVID-19
CDC uses primary and secondary criteria to determine COVID-19 Travel Health Notice levels
Primary Criteria
CDC reviews data reported to the World Health Organizationexternal icon to determine a destination’s COVID-19 Travel Health Notice level.
Primary criteria for destinations with populations over 200,000
- Incidence rate (cumulative new cases per 100,000 people over the past 28 days)
- New case trajectory (Are new cases over the past 28 days increasing, decreasing, or stable?)
| LEVEL 4
VERY HIGH Level |
LEVEL 3
HIGH Level |
LEVEL 2
MODERATE Level |
LEVEL 1
LOW Level |
|
|---|---|---|---|---|
| Incidence Rate
(cases per 100,000 people over past 28 days) |
More than 100 | 51–100 | 5–50 | Less than 5 |
Primary criteria for destinations with a population of 200,000 or less
- COVID-19 case counts (cumulative new cases over the past 28 days)
- New case trajectory (Are new cases over the past 28 days increasing, decreasing, or stable?)
| LEVEL 4
VERY HIGH Level |
LEVEL 3
HIGH Level |
LEVEL 2
MODERATE Level |
LEVEL 1
LOW Level |
|
|---|---|---|---|---|
| Case Count
(over past 28 days) |
More than 100 | 51–100 | 10–50 | Less than 10 |
Secondary Criteria
CDC uses hospitalization rates and cumulative testing positivity rate as secondary criteria to validate the primary criteria. Both primary and secondary criteria are measured over 28 days. Secondary criteria data are obtained from official sources, such as ministry of health websites. CDC reviews secondary criteria for all destinations, regardless of population size.
Lowering a Travel Health Notice Level
- A destination is eligible to move to a lower level when it meets the primary criteria for a lower level for 28 consecutive days (2 incubation periods). The incubation period is the time it can take for a person to develop infection after being exposed to the virus that causes COVID-19.
- When a destination meets primary criteria for 28 consecutive days, then secondary criteria are reviewed.
- Secondary criteria are met when hospitalization rates are stable or decreasing and cumulative testing positivity rates are in line with primary criteria data.
- A destination’s THN level is lowered if both primary criteria and secondary criteria are met.
- If secondary criteria are unavailable or are inconsistent, the destination remains at its current THN level and is reevaluated.
Raising a Travel Health Notice Level
- A destination’s THN level is increased when its primary criteria meet the range of a higher THN level for 14 consecutive days.
- CDC may raise a destination’s THN level before 14 days if the primary criteria demonstrate a sudden or abrupt increase in COVID-19 levels for 7–14 consecutive days instead of the usual 14 days.