Centers for Disease Control and Prevention (CDC) has updated its travel rules, adding Puerto Rico and Switzerland to the highest-risk locations. CDC encourages travelers to avoid places under the “Level 4: Covid-19 Very High” type. According to the organization, travelers should have received the complete shots of COVID-19 vaccine if the reason for travel is really important. The list consists of Level 1 (“low”) to Level 4 (“very high”) types. Azerbaijan, Estonia, Guam, North Macedonia, Puerto Rico, Saint Lucia, and Switzerland are the travel destinations that moved from the “Level 3: Covid-19 High” list to Level 4 last August 30. Based on CDC’s data, in the past 28 days, the places under the Level 4 category have had more than 500 cases per 100,000 residents, while Level 3 locations have had between 100 and 500 cases per 100,000 residents. Places such as Bermuda, Canada, Germany, and Moldova also moved up to Level 3 from Level 2, while Bahrain, Indonesia, Namibia, Oman, Rwanda, and Zimbabwe dropped from Level 4. With this, CDC advises travelers who have not received a COVID-19 vaccine yet to avoid unimportant travels to these high-risk locations.