The U.S. Centers for Disease Control and Prevention (CDC) updated its list of the riskiest countries to travel to during the Coronavirus Disease 2019 (COVID-19) pandemic on Aug. 9. Notably, 16 of the 20 most vaccinated countries in the world have had Level 3 (high) or Level 4 (very high) incidence rates of COVID-19 cases in the past month.
The CDC uses “Travel Health Notices (THNs) to alert travelers and other audiences to health threats around the world and advise on how to protect themselves.” The THN risk assessment levels for COVID-19, which apply to international and domestic destinations, range from Level 1 to Level 4. The CDC modified its 3-level notice system into a 4-level system on Nov. 21, 2020 to align with the 4-level structure used by the U.S. Department of State’s Travel Advisory system.
Thresholds to determine the THN level are based on the number of COVID-19 cases in an area. For populations of over 100,000 people, the incidence rate, or “cumulative new cases over the past 28 days per 100,000 population,” and upward or downward trend of new cases is taken into account.
The thresholds are set at more than 500, 100-500, 50-99, and fewer than 50 new cases per 100,000 over the past month for Levels 4, 3, 2, and 1, respectively. For populations less than 100,000, the same criteria and numbers are used, but the thresholds are based on cumulative new cases over the past month rather than adjusting for per 100,000 population.
The following are the CDC’s THN levels, along with a list of the most vaccinated countries in the world according to the Johns Hopkins Coronavirus Resource Center as of Aug. 14, with the percent fully vaccinated in parentheses.
Level 4: COVID-19 Very High
- Malta (80.18%)
- United Arab Emirates (73.69%)
- Iceland (70.67%)
- Seychelles (70.22%)
- Uruguay (69.25%)
- Chile (68.03%)
- Bahrain (65.15%)
- Portugal (63.83%)
- Spain (62.72%)
- Mongolia (62.53%)
- Ireland (61.64%)
- United Kingdom (60.16%)
- Israel (59.77%)
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For Level 4 countries, the CDC says to “Avoid travel to these destinations. If you must travel to these destinations, make sure you are fully vaccinated before travel.”
Level 3: COVID-19 High
- Belgium (65.92%)
- Qatar (65.90%)
- Denmark (63.63%)
For Level 3 countries, the CDC recommends “you are fully vaccinated before traveling to these destinations. Unvaccinated travelers should avoid nonessential travel to these destinations.”
Singapore (71.39%) and Canada (63.67%) fell into Level 2, with the recommendation to be “fully vaccinated before traveling to these destinations. Unvaccinated travelers who are at increased risk for severe illness from COVID-19 should avoid nonessential travel to the these destinations.”
The remaining 2 countries in the top 20 most vaccinated countries list, San Marino (69.99%) and Bhutan (62.33%), were listed as “Level Unknown.” The CDC said to “Avoid travel to these destinations. If you must travel to these destinations, make sure you are fully vaccinated before travel.”
The travel recommendations for each level are oddly similar, since the CDC says people should be fully vaccinated regardless of the THN level of a country and the percentage of fully vaccinated people. The incidence of COVID-19 in the past month was high enough in 16 out of the 20 most vaccinated countries in the world for the CDC to assign a Level 3 or 4 threat level.
The findings echo reports of waning COVID-19 vaccine efficacy and potential for spread of the SARS-CoV-2 virus regardless of vaccination status. A preprint study published on Aug. 8 showed that in several states in the U.S. in July, coinciding with the dominance of the Delta variant, the Pfizer-BioNTech vaccine was only 42% effective at preventing infection, while the Moderna vaccine’s efficacy fell to 76%.
In an interview published on Aug. 1, Dr. Anthony Fauci, U.S. National Institute of Allergy and Infectious Diseases (NIAID) director and chief medical advisor to the president, stated, “when you look at the level of virus in the nasopharynx of people who are vaccinated, who get breakthrough infections, it’s really quite high and equivalent to the level of virus in the nasopharynx of unvaccinated people who get infected.”
CDC Director Dr. Rochelle Walensky stated on July 3 that “High viral loads suggest an increased risk of transmission and raised concern that, unlike with other variants, vaccinated people infected with Delta can transmit the virus.” The viral loads indicate that “even fully immunized people can spread the virus as easily as unvaccinated people who become infected,” a New York Times article states.