RELATED: If You’re Unvaccinated, You’re Barred From This as of Nov. 8.ae0fcc31ae342fd3a1346ebb1f342fcb According to the latest update posted by the agency on Nov. 1, Russia has been elevated to the top risk tier of “Level 4: COVID-19 Very High.” The CDC also added Belgium, Burkina Faso, and Slovakia to the highest travel risk level due to their recently elevated case counts on the same day. “Because of the current situation in Russia, even fully vaccinated travelers may be at risk for getting and spreading COVID-19 variants,” the agency warns in its advisory. “Travelers should follow recommendations or requirements in Russia, including wearing a mask and staying six feet apart from others.” The CDC advises that all travel to any countries listed as “Level 4” should be avoided if at all possible. The agency determines risk level based on recently reported cases, with the top tier designated as any place where more than 500 cases per 100,000 residents have been recorded in the past 28 days. RELATED: If You Notice This at a Restaurant, Don’t Eat There, Virus Experts Warn. The CDC urges that anyone who absolutely must travel to destinations in the top risk tier should be fully vaccinated before doing so. In their baseline guidance, the health agency still recommends that travelers get their shots before any international trip, regardless of the destination country’s risk level. Returning travelers also face re-entry restrictions that are still in place, requiring a negative COVID-19 test taken within 72 hours of their return flight, regardless of vaccination status. Notably, as of Nov. 8, unvaccinated citizens will be required to produce a negative test taken within 24 hours of their return voyage to be allowed re-entry into the U.S. “Fully vaccinated travelers are less likely to get and spread COVID-19,” the agency states on their website. “However, international travel poses additional risks, and even fully vaccinated travelers might be at increased risk for getting and possibly spreading some COVID-19 variants.” For more travel news sent straight to your inbox, sign up for our daily newsletter.  While newly reported cases are one way to gauge how risky travel to an area may be, experts point out that there are other indicators that can be helpful when planning any potential trips. “The transmission rates are one guidepost. Another is what precautions are required and followed in the place that you’re going and then the third is what are you planning to do once you’re there,” Leana Wen, MD, an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health, told CNN. “Are you planning to visit a lot of attractions and go to indoor bars? That’s very different from you’re going somewhere where you’re planning to lie on the beach all day and not interact with anyone else,” Wen explained, adding that all international travelers should be vaccinated before leaving the U.S. RELATED: You’re Now Banned From Visiting These 3 Destinations, Even If You’re Vaccinated.